JP2009299865A - Damping force variable damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a damping force variable damper having a variable damping force without generating operating cost and generating a discontinuous damping force. <P>SOLUTION: The damping force variable damper 1 having the variable damping force is used for a vehicle suspension device. The damper includes a cylinder 2 filled with fluid, an outer piston 4 provided at the end of a piston rod 3 located in the cylinder 2 so as to be slidable on the inner peripheral face of the cylinder 2, an inner piston 5 arranged in the outer piston 4 so as to be slidable on the inner peripheral face of the outer piston 4, a first fluid passage 4a for making the fluid in the outer piston 4 communicate with fluid outside the outer piston, a second fluid passage 5a provided in the inner piston 5 for making the fluid in the outer piston 4 defined by the inner piston 5 with fluid inside the outer piston, and damping force adjusting means 6, 7, 10 for continuously varying the damping forces generated in the second fluid passage 5a according to the amplitude of the outer piston 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a damping force variable damper that is used in a vehicle suspension device and makes a damping force variable.

  As a damping force variable damper, one that makes a damping force variable using a magnetorheological fluid has been proposed (see, for example, Patent Document 1). In order to make the damping force variable using a magnetorheological fluid, it is necessary to change the magnetic force applied to the magnetorheological fluid. Normally, since the magnetism is made variable using an electromagnet, electric power is supplied to the damping force variable damper. It is necessary to supply.

Further, a damping force variable damper that makes the damping force variable without using a magnetorheological fluid has been proposed (for example, see Non-Patent Document 1). Since this damping force variable damper does not use a magnetorheological fluid, it is not necessary to receive power supply.
JP 2006-77787 A Motor Fan illustrated Motor fan separate volume / Damper technology, “Chapter5 Variable damping force system / Focus on comfort in the normal range, optimization of frequency characteristics”, page 046, October 2007 Issued 29th

  In the damping force variable damper of Patent Document 1, it is necessary to supply electric power in order to make the damping force variable.

  In the damping force variable damper of Non-Patent Document 1, there is a switching point of the flow path because the fluid flows by switching between two flow paths having different damping forces, and a discontinuity of the damping force that changes at this switching point occurs. There was a problem. As a result, a stepped feeling is created when the damping force variable damper vibrates, and the ride comfort may be deteriorated.

  The present invention solves these problems, and provides a damping force variable damper that can vary the damping force without causing an operation cost and without causing a discontinuity of the damping force. The purpose is to do.

The present invention is a damping force variable damper that is used in a vehicle suspension system and makes the damping force variable,
A cylinder filled with fluid,
A piston rod provided to penetrate one end of the cylinder;
An outer piston provided at an end portion of the piston rod located inside the cylinder, and slidably provided on an inner peripheral surface of the cylinder;
An inner piston disposed inside the outer piston and slidably provided on an inner peripheral surface of the outer piston;
A first fluid passage through which the fluid flows between the inside and outside of the outer piston;
A second fluid passage provided in the inner piston and allowing the fluid to flow between the insides of the outer piston partitioned by the inner piston;
And a damping force adjusting means for continuously changing the damping force generated in the second fluid passage in accordance with the amplitude amount of the outer piston.

  According to the characteristics of the present invention, the flow rate of the fluid flowing between the inside of the cylinder and the inside of the outer piston is continuously increased or decreased via the first fluid passage according to the amplitude amount of the outer piston. In accordance with the flow rate of the fluid, the relative amplitude of the inner piston with respect to the outer piston continuously increases and decreases. Therefore, since the relative amplitude amount of the inner piston continuously increases or decreases according to the amplitude amount of the outer piston, the damping force adjusting means generates the damping force generated in the second fluid passage according to the amplitude amount of the outer piston. Can be realized by continuously changing the damping force generated in the second fluid passage provided in the inner piston in accordance with the relative amplitude of the inner piston. And, according to the damping force adjusting means, instead of switching the two flow paths having different damping forces as in Non-Patent Document 1, the damping force generated in the second fluid passage is continuously changed. It is possible to suppress the occurrence of a step feeling when the damping force variable damper vibrates, and it is possible to suppress deterioration in ride comfort. In addition, since it is not necessary to supply power to make the damping force variable, there is no operation cost.

The damping force adjusting means is
When the fluid flows into the outer piston from the first fluid passage, a first biasing force that continuously changes the inner piston in accordance with the flow rate of the fluid in a direction opposite to the inflow direction. First elastic means for energizing with,
Second elastic means for urging the inner piston with a second urging force continuously changing in accordance with the relative amplitude in the same direction as the first urging force;
A valve body is provided at the tip of the second elastic means, and a valve seat is provided in the second fluid passage, and acts on the valve body by the second urging force and the pressure of the fluid passing through the second fluid passage. It is preferable to include a first valve mechanism that opens the second fluid passage when the force balances.

  In addition to the relative amplitude of the inner piston continuously changing according to the amplitude of the outer piston, the second elastic means continuously applies the second biasing force according to the relative amplitude. When the second urging force continuously changed by the first valve mechanism and the force acting on the valve body by the pressure of the fluid passing through the second fluid passage are balanced, the second fluid passage is opened, The damping force generated in the two fluid passages can be continuously changed. And according to the said 1st elastic means, the force which acts on the said valve body which balances the said 2nd urging | biasing force can be regulated. Further, when the amplitude amount of the outer piston is small, the amplitude amount of the inner piston is small, and the second urging force and the force acting on the valve body due to the pressure of the fluid passing through the second fluid passage are not balanced, The fluid pressure is balanced with the continuously changing first biasing force, and a continuously changing damping force can be generated in the fluid. As described above, since the damping force corresponding to the balance between the fluid pressure generated when the outer piston vibrates and the first urging force and the second urging force that change continuously can be generated, the damping force that changes continuously. Can be generated.

The first biasing force is proportional to a product of a pressure difference between fluid chambers partitioned by the inner piston inside the inner piston and a pressure receiving area where the inner piston receives the pressure of the fluid,
The second urging force is proportional to the product of a pressure difference between fluid chambers partitioned by the inner piston within the inner piston and a pressure receiving area where the first valve mechanism receives the pressure of the fluid,
The first elastic means and the second elastic means have different spring constants,
The damping force adjusting means is
When the amplitude amount of the outer piston is less than a predetermined value, the second urging force is larger than the first urging force, the second fluid passage is closed,
When the amplitude amount of the outer piston is equal to or greater than a predetermined value, it is preferable that the second urging force is equal to or less than the first urging force and the second fluid passage is opened.

  Since the first urging force and the second urging force continuously change according to the amplitude amount of the outer piston, and the magnitude relationship is switched at a predetermined value, the magnitudes of the first urging force and the second urging force at the predetermined value. They are equal. When the second fluid passage is closed, a damping force is generated according to the first biasing force, and when the second fluid passage is opened, a damping force is generated according to the second biasing force. The damping force around the predetermined value is in a continuous state. As described above, not only the damping force generated according to the first biasing force continuously changes and the damping force generated according to the second biasing force continuously changes, but also the first biasing force and the second biasing force. Even when the power is switched, the damping force continuously changes. For this reason, a step feeling can be reduced when the damping force variable damper vibrates, and deterioration of the riding comfort can be suppressed.

Further, the first elastic means and the second elastic means have different spring constants,
The damping force adjusting means is
A valve body is provided at the tip of the first elastic means, a valve seat is provided in the second fluid passage, and a force acting on the valve body by the first urging force and the pressure of the fluid passing through the second fluid passage. And a second valve mechanism that opens the second fluid passage when balanced with,
The inner piston is preferably provided with the second fluid passage, the first valve mechanism, and the second valve mechanism.

  As in the case of the first valve mechanism, by using the second valve mechanism, the relative amplitude amount of the inner piston continuously changes according to the amplitude amount of the outer piston, The first urging force is continuously changed according to the relative amplitude amount by the elastic means, and the first urging force continuously changing by the second valve mechanism and the pressure of the fluid passing through the second fluid passage. When the force acting on the valve body is balanced, the damping force generated in the second fluid passage can be continuously changed by opening the second fluid passage.

  ADVANTAGE OF THE INVENTION According to this invention, the damping force variable damper which can vary a damping force without generating discontinuity of a damping force without generating operation cost can be provided.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
FIG. 1 is a perspective view of the damping force variable damper 1 according to the first embodiment of the present invention, and FIG. 2 is a mechanism diagram of the damping force variable damper 1 according to the first embodiment of the present invention. The damping force variable damper 1 is used in a suspension device for a vehicle such as a motorcycle or a four-wheel vehicle, and can quickly attenuate vibrations generated in the vehicle.

  The damping force variable damper 1 is positioned inside the cylinder 2 of the piston rod 3, a cylinder 2 filled with a gas or liquid fluid, a piston rod 3 provided so as to penetrate one end of the cylinder 2, and the piston rod 3. It has an outer piston 4 provided at an end and slidably provided on the inner peripheral surface of the cylinder 2. The outer piston 4 is fixed to the piston rod 3 by a nut 14.

  A piston ring 4b is provided on the outer periphery of the end of the outer piston 4, and this piston ring 4b is in contact with the inner peripheral surface of the cylinder 2 and slides as the vehicle vibrates. The outer piston 4 has a cylindrical portion 4c and a bottom portion 4d having a piston ring 4b formed on the outer periphery, and a connecting surface between the cylindrical portion 4c and the bottom portion 4d is sealed by an O-ring 4e. The outer piston 4 functions as a cylinder with respect to the inner piston 5 described later.

  The outer piston 4 divides the inside of the cylinder 2 into two chambers, a first fluid chamber 15 and a fourth fluid chamber 18. The first fluid chamber 15 is provided on the piston rod 3 side, and the fourth fluid chamber 18 is provided on the opposite side of the first fluid chamber 15 with the outer piston 4 interposed therebetween.

  An inner piston 5 is disposed inside the outer piston 4. The inner piston 5 is provided on the inner peripheral surface of the outer piston 4 so as to be slidable. The inner piston 5 divides the interior of the outer piston 4 into two chambers, a second fluid chamber 16 and a third fluid chamber 17. The second fluid chamber 16 is provided on the first fluid chamber 15 side, and the third fluid chamber 17 is provided on the opposite side of the second fluid chamber 16 across the inner piston 5. The third fluid chamber 17 is provided on the fourth fluid chamber 18 side.

  A plurality of first fluid passages 4a are provided on the upper end surface and the lower end surface of the outer piston 4, respectively. The first fluid passage 4a on the upper end surface of the outer piston 4 communicates between the first fluid chamber 15 outside the outer piston 4 and the second fluid chamber 16 inside the outer piston 4, and the fluid is The fluid flows from the first fluid chamber 15 to the second fluid chamber 16 and from the second fluid chamber 16 to the first fluid chamber 15. The first fluid passage 4a on the lower end surface of the outer piston 4 communicates between the fourth fluid chamber 18 outside the outer piston 4 and the third fluid chamber 17 inside the outer piston 4, and the fluid is The fluid flows from the fourth fluid chamber 18 to the third fluid chamber 17 and from the third fluid chamber 17 to the fourth fluid chamber 18.

The inner piston 5 is provided with a plurality of second fluid passages 5a. The second fluid passage 5a communicates between the second fluid chamber 16 and the third fluid chamber 17 inside the outer piston 4, and the fluid flows from the second fluid chamber 16 to the third fluid chamber 17, and It flows from the third fluid chamber 17 to the second fluid chamber 16.

  Moreover, the damping force variable damper 1 has damping force adjusting means. The damping force adjusting means includes first elastic means 6, second elastic means 7, and first valve mechanism 10. The damping force adjusting means continuously changes the damping force generated in the second fluid passage 5a in accordance with the amplitude amount of the outer piston 4.

  As the first elastic means 6, for example, a coil spring wound around the piston rod 3 can be used as shown in FIGS. 1 and 2. The first elastic means 6 includes a first elastic means 6 a provided in the second fluid chamber 16 and a first elastic means 6 b provided in the third fluid chamber 17. The first elastic means 6 a biases the inner piston 5 with a first biasing force in the direction from the second fluid chamber 16 to the inner piston 5. The first elastic means 6 b urges the inner piston 5 with a first urging force in the direction from the third fluid chamber 17 to the inner piston 5.

  As the second elastic means 7, for example, a coil spring can be used as shown in FIGS. 1 and 2. The second elastic means 7 includes a second elastic means 7 a provided in the second fluid chamber 16 and a second elastic means 7 b provided in the third fluid chamber 17.

  The second elastic means 7a is partially inserted into holes provided in the upper surface of the inner piston 5 facing the second fluid chamber 16 and the inner surface of the outer piston 4 facing the upper surface. Expansion and contraction of the second elastic means 7a is guided. Further, one end of the second elastic means 7 a is fixed to the bottom of a hole provided in the inner surface of the outer piston 4. And the 1st fluid channel | path 4a is arrange | positioned in the position of this hole. A second fluid passage 5a is disposed at a hole provided in the upper surface of the inner piston 5 facing the second fluid chamber 16. The second elastic means 7a biases the inner piston 5 with a second biasing force through the valve body 8a in the direction from the second fluid chamber 16 to the inner piston 5.

  A part of the second elastic means 7b is inserted into a hole provided in each of the lower surface of the inner piston 5 facing the third fluid chamber 17 and the inner surface of the outer piston 4 facing the lower surface. Expansion and contraction of the second elastic means 7b is guided. Further, one end of the second elastic means 7 b is fixed to the bottom of a hole provided in the inner surface of the outer piston 4. And the 1st fluid channel | path 4a is arrange | positioned in the position of this hole. Further, the second fluid passage 5 a is arranged at the position of the hole provided in the lower surface facing the third fluid chamber 17 of the inner piston 5. The second elastic means 7b biases the inner piston 5 with the second biasing force through the valve body 8b in the direction from the third fluid chamber 17 to the inner piston 5.

  In addition, although mentioned later for details, the spring constant of the 2nd elastic means 7b is set larger than the spring constant of the 2nd elastic means 7a. Thereby, in the damping force variable damper 1, the damping force at the time of pulling can be made larger than the damping force at the time of compression in a state where the vibration is increasing.

  As the first valve mechanism 10, for example, as shown in FIGS. 1 and 2, a poppet valve having a spherical valve body 8 and a valve seat 9 having a tapered surface can be used. In the first valve mechanism (poppet valve) 10, the valve body 8 is closed by contacting the valve seat 9, and the valve body 8 is opened by being separated from the valve seat 9. The valve body 8 includes a valve body 8a provided at the tip of the second elastic means 7a and a valve body 8b provided at the tip of the second elastic means 7b.

  The first valve mechanism 10a is closed by the valve body 8a being pressed (biased) with the second urging force by the second elastic means 7a to the valve seat 9a. The first valve mechanism 10b is closed by the valve body 8b being pressed against (biased) the valve seat 9b with the second urging force by the second elastic means 7b. Thus, the valve body 8a and the corresponding valve seat 9a (9) constitute the first valve mechanism 10a, and the valve body 8b and the corresponding valve seat 9b (9) constitute the first valve mechanism 10b. Is configured. The valve seat 9 (9a, 9b) is provided in the second fluid passage 5a, and can open and close the second fluid passage 5a by opening and closing the first valve mechanism 10 (10a, 10b). it can.

  Next, the operation of the damping force variable damper 1 will be described. In the description, the compression state of the damping force variable damper 1 in a state where the amplitude of vibration is decreasing will be described as an example. The tension state in which the amplitude is increasing can be read by changing the subscript a to b, for example, by changing the first valve mechanism 10a to the first valve mechanism 10b.

  FIG. 3A shows a state where the damping force variable damper 1 is in the A state where the amplitude of the outer piston 4 is small and has not reached the blow point. In the damping force variable damper 1, the vibration amplitude is reduced, and the piston rod 3 and the outer piston 4 are connected from the first fluid chamber 15 in which the piston rod 3 is disposed to the fourth fluid chamber 18. Moving in the direction. By this movement, the fluid flows from the fourth fluid chamber 18 to the third fluid chamber 17 and from the second fluid chamber 16 to the first fluid chamber 15 through the first fluid passage 4 a. By these flows, the volume of the second fluid chamber 16 decreases, the volume of the third fluid chamber 17 increases, and the inner piston 5 moves in the direction from the third fluid chamber 17 to the second fluid chamber 16 in the direction of the outer piston. Move relative to 4. That is, when fluid flows into the inside of the outer piston 4 (third fluid chamber 17) from the first fluid passage 4a, the inner piston 5 moves in the inflow direction. From the above, it can be seen that the movement amount (displacement) of the inner piston 5 has a correlation with the movement amount (displacement) of the outer piston 4.

Due to the movement of the inner piston 5, the first elastic means 6a and the second elastic means 7a contract. In the 1st elastic means 6a, it shrinks according to the movement amount of the inner piston 5 (according to the flow volume into which the fluid flowed), and the said 1st biasing force with respect to the inner piston 5 increases continuously. With this continuous increase, the fluid is prevented from moving between the chambers, and this damping force continuously increases in a direction that prevents the displacement of the piston rod 3.

  FIG. 4 shows the relationship between the pressure received by the inner piston 5 from the fluid and the pressure received by the valve body 8a of the first valve mechanism 10a from the fluid with respect to the piston displacement of the outer piston 4.

  The first urging force balances with the force calculated by the product of the pressure received by the inner piston 5 from the fluid and the pressure receiving area where the inner piston 5 receives the pressure of the fluid, and the forces are proportional to each other. . Further, from the above, it is known that the movement amount (displacement) of the inner piston 5 has a correlation with the movement amount (displacement) of the outer piston 4, so that as shown in FIG. For the amount of movement (displacement) of 4, the pressure that the inner piston 5 receives from the fluid has a proportional relationship.

  Similarly, the second elastic means 7a contracts according to the amount of movement of the inner piston 5 (according to the flow rate of fluid flow), and the second urging force against the inner piston 5 continuously increases. The second urging force is equal to the force calculated by the product of the pressure received by the valve body 8a of the first valve mechanism 10a from the fluid and the pressure receiving area where the valve body 8a of the first valve mechanism 10a receives the pressure of the fluid. In balance, the forces of each other are proportional. Similarly, since it is known that the movement amount (displacement) of the inner piston 5 has a correlation with the movement amount (displacement) of the outer piston 4, as shown in FIG. 4 has a proportional relationship with the pressure that the valve body 8a of the first valve mechanism 10a receives from the fluid. In addition, as shown in FIG. 4, in order to make the magnitude | size of the linear inclination of the pressure which the inner piston 5 receives from a fluid differ from the magnitude | size of the linear inclination of the pressure which the valve body 8a of the 1st valve mechanism 10a receives from a fluid, Different spring constants may be set for the first elastic means 6a and the second elastic means 7a. The straight line of the pressure received from the fluid by the valve body 8a of the first valve mechanism 10a has a non-zero value on the pressure axis (when the piston displacement of the outer piston is zero). This is because it is set after being compressed.

  FIG. 4 shows that in the state A, the pressure received by the inner piston 5 from the fluid and the pressure received by the valve body 8a of the first valve mechanism 10a from the fluid take different values for each piston displacement of the outer piston. In practice, the fluid takes only one pressure value for each piston displacement of the outer piston. The actual pressure matches the pressure that the lower inner piston 5 receives from the fluid, and the pressure that the valve body 8a of the first valve mechanism 10a receives from the fluid also matches the pressure that the inner piston 5 receives from the fluid. The differential pressure between the pressure received by the valve body 8a of the first valve mechanism 10a and the pressure received by the inner piston 5 from the fluid closes the valve body 8a of the first valve mechanism 10a against the valve seat 9a. Will be used.

  FIG. 5 shows the relationship of the damping force generated in the damping force variable damper 1 in each of the A state, the B state, and the C state with respect to the piston speed of the outer piston 4.

  In the A state, the damping force generated in the damping force variable damper 1 is proportional to the piston speed of the outer piston 4. It can be seen that when the piston speed of the outer piston 4 increases, the damping force generated in the damping force variable damper 1 also increases slightly compared to the B state and the C state. This increase is considered to be due to an increase in flow resistance caused by the fluid flow path being restricted by the first fluid passage 4a.

  FIG. 3B shows a state at the blow point as the B state of the damping force variable damper 1. The damping force variable damper 1 is in a state where the amplitude of vibration is further increased from the state A, and the piston rod 3 and the outer piston 4 are moved from the first fluid chamber 15 in which the piston rod 3 is disposed to the fourth position. The fluid further moves from the A state in the direction toward the fluid chamber 18, and the fluid further flows from the fourth fluid chamber 18 to the third fluid chamber 17 through the first fluid passage 4 a and from the A state to the second fluid chamber 16. To the first fluid chamber 15. Further, the volume of the second fluid chamber 16 decreases, the volume of the third fluid chamber 17 increases, and the inner piston 5 moves in the direction from the third fluid chamber 17 to the second fluid chamber 16 in the A state. Furthermore, it moves relative to the outer piston 4. The first elastic means 6a and the second elastic means 7a are further contracted from the A state.

  As shown in FIG. 4, in the B state (blow point), the pressure received by the inner piston 5 from the fluid coincides with the pressure received by the valve body 8a of the first valve mechanism 10a from the fluid. The actual fluid pressure also matches these pressures. The second urging force is a force calculated by the product of the pressure received by the valve body 8a of the first valve mechanism 10a from the fluid and the pressure receiving area where the valve body 8a of the first valve mechanism 10a receives the pressure of the fluid. Match to match. The valve body 8a of the first valve mechanism 10a is separated from the valve seat 9a without being pressed against it, and the first valve mechanism 10a is opened.

  As shown in FIG. 5, in the B state (blow point), the damping force generated in the damping force variable damper 1 is substantially proportional to the piston speed of the outer piston 4. As the piston speed of the outer piston 4 increases, the damping force generated in the damping force variable damper 1 also increases, and it can be seen that the rate of increase is greater than that in the A state. The increase rate is increased not only because the flow path of the fluid is restricted by the second fluid passage 5a, but also the flow path generated between the valve body 8a and the valve seat 9a of the first valve mechanism 10a. It is thought that this is because the flow resistance is increased by the second urging force.

  FIG. 3C shows a state in which the amplitude of the outer piston 4 increases beyond the blow point (B state) as the C state of the damping force variable damper 1. In the damping force variable damper 1, the vibration amplitude is further increased from the B state, and the piston rod 3 and the outer piston 4 are further in the first fluid chamber in which the piston rod 3 is disposed from the B state. 15 moves from the fourth fluid chamber 18 to the third fluid chamber 17 via the first fluid passage 4a and flows from the fourth fluid chamber 18 to the third fluid chamber 17 via the first fluid passage 4a. To the first fluid chamber 15. Further, the volume of the second fluid chamber 16 decreases, the volume of the third fluid chamber 17 increases, and the inner piston 5 moves in the direction from the third fluid chamber 17 to the second fluid chamber 16 in the B state. Furthermore, it moves relative to the outer piston 4. The first elastic means 6a and the second elastic means 7a are further contracted from the B state.

  As shown in FIG. 4, in the C state, the pressure that the inner piston 5 receives from the fluid and the pressure that the valve body 8a of the first valve mechanism 10a receives from the fluid take different values for each piston displacement of the outer piston. In practice, the fluid takes only one pressure value for each piston displacement of the outer piston. The actual pressure matches the pressure that the lower valve body 8a of the first valve mechanism 10a receives from the fluid, and the pressure that the inner piston 5 receives from the fluid is also received by the valve body 8a of the first valve mechanism 10a from the fluid. It corresponds to the pressure. Since the pressure received by the valve body 8a of the first valve mechanism 10a from the fluid and the actual pressure of the fluid coincide with each other, the second biasing force is the pressure received by the valve body 8a of the first valve mechanism 10a from the fluid, The valve body 8a of the first valve mechanism 10a balances with the force calculated by the product of the pressure receiving area that receives the fluid pressure. The valve body 8a of the first valve mechanism 10a is separated from the valve seat 9a without being pressed against it, and the first valve mechanism 10a is opened.

  In other words, when the displacement (amplitude amount) of the outer piston 4 in the A state is less than a predetermined value (blow point), the second urging force is greater than the first urging force, and the first valve mechanism 10a is closed. Thus, the second fluid passage 5a is closed, and the force continuously increases in a direction that prevents the displacement of the piston rod 3 in accordance with the continuous increase of the first urging force. When the displacement (amplitude amount) of the outer piston 4 in the B state and the C state is equal to or greater than a predetermined value (blow point), the second urging force becomes equal to or less than the first urging force, and the first valve mechanism 10a opens. Thus, the second fluid passage 5a is opened. And according to the continuous increase of the 2nd urging | biasing force, the pressure of the fluid at the time of valve opening of the 1st valve mechanism 10a will increase continuously, and a damping force will increase continuously.

  In the B state where the A state and the C state are connected, qualitatively, the first valve mechanism 10a is barely opened, and the main force of the damping force generated by the damping force variable damper 1 is suddenly increased. Therefore, the first valve mechanism 10a is not shifted to. For this reason, the damping force can be continuously changed from the A state to the C state via the B state.

  As shown in FIG. 5, in the C state, the damping force generated in the damping force variable damper 1 is substantially proportional to the piston speed of the outer piston 4. As the piston speed of the outer piston 4 increases, the damping force generated in the damping force variable damper 1 also increases, and it can be seen that the rate of increase is as large as in the B state. However, the damping force itself is larger than the B state over the entire piston speed of the outer piston. The increase in the damping force is caused between the valve body 8a of the first valve mechanism 10a and the valve seat 9a because the second elastic means 7a contracts from the state B and becomes a second urging force. This is probably because the flow path is narrowed and the flow resistance is increased. Even when the piston speed of the outer piston 4 is low, the flow path between the valve body 8a and the valve seat 9a of the first valve mechanism 10a is restricted in the B state and the C state, so that a relatively large damping force can be obtained. Therefore, the driving performance of the vehicle can be improved.

(Second Embodiment)
FIG. 6 is a perspective view of the damping force variable damper 1 according to the second embodiment of the present invention, and FIG. 7 is a mechanism diagram of the damping force variable damper 1 according to the second embodiment of the present invention. is there. At first glance, FIG. 6 and FIG. 7 seem to describe the variable damping force damper 1 having a different structure, but the variable damping force damper 1 having the same structure is shown. In FIG. 6, the first elastic means 6a and the second elastic means 7a arranged on the upper side of the inner piston 5 with the piston rod 3 interposed therebetween are shown in FIG. 7 in order to facilitate understanding of the mechanism. 3 is expanded on the right side. Similarly, in FIG. 6, the first elastic means 6 b and the second elastic means 7 b disposed below the inner piston 5 with the piston rod 3 interposed therebetween are shown in FIG. 7 to facilitate understanding of the mechanism. Furthermore, it is developed on the left side of the piston rod 3.

The damping force variable damper 1 of the second embodiment is different from the damping force variable damper 1 of the first embodiment in that the two second elastic means 7a are different in the damping force variable damper 1 of the first embodiment. Although the piston rod 3 is disposed between the damping force variable damper 1 of the second embodiment, the second elastic means 7a is reduced to one as shown in FIG. The elastic means 6a has moved to a position that sandwiches the piston rod 3 with the second elastic means 7a. As shown in FIG. 7, a valve body 11a is provided at the tip of the first elastic means 6a, a valve seat 12a is provided in the second fluid passage 5a, and the valve body 11a and the valve seat 12a are connected to a second valve mechanism ( A poppet valve) 13a. Similarly, in the damping force variable damper 1 of the second embodiment, as shown in FIG. 6, the second elastic means 7b is reduced to one, and instead, the first elastic means 6b is replaced with the second elastic means. 7b and the piston rod 3 is moved to a position sandwiched therebetween. As shown in FIG. 7, a valve body 11b is provided at the tip of the first elastic means 6b, a valve seat 12b is provided in the second fluid passage 5a, and the second valve mechanism 13b is composed of the valve body 11b and the valve seat 12b. Is configured. The second valve mechanism 13b also belongs to the damping force adjusting means. When the first urging force, the fluid pressure, and the product of the pressure receiving areas of the valve bodies 11a and 11b are balanced, the second valve mechanisms 13a and 13b are opened, and the second fluid passage 5a is opened. The inner piston 5 is provided not only with the first valve mechanism 10 (10a, 10b) but also with the second valve mechanism 13 (13a, 13b).

  FIG. 8 shows a simulation result of the relationship of the blow pressure with respect to the piston displacement of the outer piston 4 of the damping force variable damper 1 of the second embodiment. The blow pressure is a pressure that the outer piston 4 receives from the fluid, and the damping force generated in the damping force variable damper 1 is considered to be proportional to the blowing pressure. It can be seen that, with respect to the piston displacement of the outer piston 4 in the tension (TENSION) direction, the blow pressure (damping force) continuously increases in accordance with the piston displacement from the piston displacement of 0 mm to 5 mm. The reason why the blow pressure (damping force) becomes constant when the piston displacement is 5 mm or more is that the inner piston 5 is seated on the outer piston 4 and does not move relatively.

Similarly, with respect to the piston displacement of the outer piston 4 in the compression (COMPRESSION) direction, the blow pressure (damping force) continuously increases according to the piston displacement from the piston displacement of 0 mm to 5 mm. The reason why the blow pressure (damping force) becomes constant when the piston displacement is 5 mm or more is that the inner piston 5 is seated on the outer piston 4 and does not move relatively.

  In order to make the blowing pressure (damping force) in the pulling direction larger than the blowing pressure (damping force) in the compression direction, the spring constant of the first elastic means 6b is set larger than the spring constant of the first elastic means 6a. ing. The spring constant of the second elastic means 7b is set larger than the spring constant of the second elastic means 7a.

  FIG. 9 shows a simulation result of the relationship of the damping force generated in the damping force variable damper 1 for each piston amplitude of the outer piston 4 with respect to the piston speed of the outer piston 4 of the damping force variable damper 1 of the second embodiment. The positive direction of the damping force is the tension (TENSION) direction, and the negative direction is the compression (COMPRESSION) direction. It can be seen that at any piston amplitude, the damping force increases on both the tension side and the compression side as the piston speed of the outer piston 4 increases. It can also be seen that when the piston amplitude is from 1 mm to 5 mm, the damping force increases on both the tension side and the compression side over the entire piston speed of the outer piston 4 as the piston amplitude increases. These trends are in good agreement with the features of FIG. That is, the transition from the A state in FIG. 5 to the C state through the B state is performed by increasing the piston amplitude from 1 mm to 5 mm in FIG. The reason why the graph of piston amplitude 5 mm and the graph of 25 mm overlap is that the piston amplitude is 5 mm or more and the inner piston 5 is seated on the outer piston 4 and does not move relatively.

  FIG. 10 shows a simulation result of the damping force characteristic when the amplitude (input amplitude) of vibration of the damping force variable damper 1 of the second embodiment is small (a state where the blow point has not been reached). FIG. 10A shows the time change of the piston displacement of the outer piston 4 and the piston displacement of the inner piston 5, FIG. 10B shows the time change of the piston speed of the outer piston 4, and FIG. The time change of the damping force which arises in the force variable damper 1 is shown. It should be noted that the positive direction of piston displacement is the direction in which the amplitude of vibration increases (TENSION). In the positive direction of the piston speed, the speed in the direction in which the amplitude of vibration increases (TENSION) is taken. In the negative direction of the damping force, a tensile (TENSION) direction is taken. Regarding the arrows traversing FIG. 10A, FIG. 10B, and FIG. 10C, the arrow at time 0.3 sec indicates the timing when the outer piston 4 is lowered most. The arrow at time 0.5 sec indicates the timing at which the outer piston 4 is raised most.

As shown in FIG. 10A, when a sine wave is input to the piston displacement of the outer piston 4, it can be seen that a positive and negative sine wave is output as the piston displacement of the inner piston 5. Further, when the waveform of the piston displacement of the outer piston 4 in FIG. 10A is differentiated, the piston speed of the outer piston 4 as shown in FIG. 10B is obtained. The piston speed of the outer piston 4 is 90 degrees out of phase with the piston displacement of the outer piston 4. From the piston displacement of the outer piston 4 in FIG. 10 (a) and the piston speed of the outer piston 4 in FIG. 10 (b), as shown in FIG. 10 (c), as a damping force, a sine wave of the piston displacement of the outer piston 4 A waveform in which positive and negative are inverted with respect to is obtained. It can be seen that the damping force changes continuously.

  FIG. 11 shows a simulation result of the damping force characteristic when the input amplitude is large (a state where the blow point is exceeded). 11A shows the time change of the piston displacement of the outer piston 4, FIG. 11B shows the time change of the piston speed of the outer piston 4, and FIG. 11C shows the damping that occurs in the damping force variable damper 1. It shows the time change of force. In addition, the positive direction of the piston displacement of the outer piston in FIG. 11A is the direction in which the amplitude of vibration increases (TENSION). In the positive direction of the piston speed of the outer piston in FIG. 11 (b), the speed in the direction in which the amplitude of vibration increases (TENSION) is taken. In the negative direction of the damping force in FIG. 11C, a tensile (TENSION) direction is taken. 11A, 11B, and 11C, the arrow at a time of about 0.4 sec indicates that the inner piston 5 is seated on the outer piston 4 and does not move relatively. Timing is shown. The arrow at about 0.52 sec also indicates the timing at which the inner piston 5 is seated on the outer piston 4 and does not move relatively.

As shown in FIG. 11A, a sine wave whose amplitude increases with time is input to the piston displacement of the outer piston 4. Furthermore, when the piston displacement waveform of the outer piston 4 in FIG. 11A is differentiated, the piston speed of the outer piston 4 as shown in FIG. 11B is obtained. The piston speed of the outer piston 4 is 90 degrees out of phase with the piston displacement of the outer piston 4. From the piston displacement of the outer piston 4 in FIG. 11A and the piston speed of the outer piston 4 in FIG. 11B, a waveform of the damping force as shown in FIG. 11C is obtained. The damping force periodically changes in level so as to synchronize with the high and low cycle of the piston speed of the outer piston 4. It can be seen that the damping force continuously decreases with a slope from the maximum value to the minimum value. It can also be seen that the damping force continuously increases with a slope from the minimum value to the maximum value.

(Third embodiment)
FIG. 12 is a perspective view of the damping force variable damper 1 according to the third embodiment of the present invention, and FIG. 13 is a mechanism diagram of the damping force variable damper 1 according to the third embodiment of the present invention. is there. The damping force variable damper 1 of the third embodiment is different from the damping force variable damper 1 of the first embodiment in that the first elastic means 6 (6a, 6b) is omitted. That is, it can be considered that the second elastic means 7 (7a, 7b) also functions as the first elastic means 6 (6a, 6b).

It is the perspective view which cut | disconnected the damping force variable damper which concerns on the 1st Embodiment of this invention. It is a mechanism figure of the damping force variable damper concerning a 1st embodiment of the present invention. (A) is a mechanism diagram of the damping force variable damper in the A state (state where the amplitude of the outer piston is small and has not reached the blow point), and (b) is a mechanism diagram of the damping force variable damper in the B state (blow point). (C) is a mechanism diagram of the damping force variable damper in the C state (a state where the amplitude of the outer piston is large beyond the blow point). It is a graph which shows the relationship between the pressure concerning an inner piston with respect to the piston displacement of an outer piston, and the pressure concerning a 1st valve mechanism. It is a graph which shows the relationship of the damping force which arises in a damping-force variable damper in each of A state, B state, and C state with respect to the piston speed of an outer piston. It is the perspective view which cut | disconnected the damping force variable damper which concerns on the 2nd Embodiment of this invention. It is a mechanism figure of the damping-force variable damper which concerns on the 2nd Embodiment of this invention. It is a graph which shows the relationship of the blow pressure (blow point) with respect to the piston displacement of an outer piston. It is a graph which shows the relationship of the damping force which arises in the damping force variable damper for every piston amplitude of an outer piston with respect to the piston speed of an outer piston. It is a damping force characteristic when the input amplitude is small (a state where the blow point has not been reached), (a) shows the time variation of the piston displacement of the outer piston and the piston displacement of the inner piston, and (b) is the piston of the outer piston. The time change of speed is shown, (c) shows the time change of the damping force generated in the damping force variable damper. These are damping force characteristics when the input amplitude is large (in a state where the blow point is exceeded), (a) shows the time change of the piston displacement of the outer piston, and (b) shows the time change of the piston speed of the outer piston. , (C) shows the time change of the damping force generated in the damping force variable damper. It is the perspective view which cut | disconnected the damping force variable damper which concerns on the 3rd Embodiment of this invention. It is a mechanism figure of the damping force variable damper which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Damping force variable damper 2 Cylinder 3 Piston rod 4 Outer piston 4a 1st fluid passage 4b Piston ring 4c Cylinder part 4d Bottom part 4e O-ring 5 Inner piston 5a 2nd fluid passage 6, 6a, 6b 1st elastic means 7, 7a, 7b Second elastic means 8, 8a, 8b Valve body 9, 9a, 9b Valve seat 10, 10a, 10b First valve mechanism 11, 11a, 11b Valve body 12, 12a, 12b Valve seat 13, 13a, 13b Second valve Mechanism 14 Nut 15 First fluid chamber 16 Second fluid chamber 17 Third fluid chamber 18 Fourth fluid chamber

Claims (4)

A damping force variable damper that is used in a vehicle suspension system and makes the damping force variable,
A cylinder filled with fluid,
A piston rod provided to penetrate one end of the cylinder;
An outer piston provided at an end portion of the piston rod located inside the cylinder, and slidably provided on an inner peripheral surface of the cylinder;
An inner piston disposed inside the outer piston and slidably provided on an inner peripheral surface of the outer piston;
A first fluid passage through which the fluid flows between the inside and outside of the outer piston;
A second fluid passage provided in the inner piston and allowing the fluid to flow between the insides of the outer piston partitioned by the inner piston;
A damping force variable damper comprising: damping force adjusting means for continuously changing the damping force generated in the second fluid passage according to the amplitude amount of the outer piston. The damping force adjusting means is
When the fluid flows into the outer piston from the first fluid passage, a first biasing force that continuously changes the inner piston in accordance with the flow rate of the fluid in a direction opposite to the inflow direction. First elastic means for energizing with,
Second elastic means for urging the inner piston with a second urging force continuously changing in accordance with the relative amplitude in the same direction as the first urging force;
A valve body is provided at the tip of the second elastic means, and a valve seat is provided in the second fluid passage, and acts on the valve body by the second urging force and the pressure of the fluid passing through the second fluid passage. A first valve mechanism that opens the second fluid passage when the force balances;
The damping force variable damper according to claim 1, comprising: The first biasing force is proportional to a product of a pressure difference between fluid chambers partitioned by the inner piston inside the inner piston and a pressure receiving area where the inner piston receives the pressure of the fluid;
The second urging force is proportional to the product of a pressure difference between fluid chambers partitioned by the inner piston within the inner piston and a pressure receiving area where the first valve mechanism receives the pressure of the fluid,
The first elastic means and the second elastic means have different spring constants,
The damping force adjusting means is
When the amplitude amount of the outer piston is less than a predetermined value, the second urging force is larger than the first urging force, the second fluid passage is closed,
3. The damping according to claim 2, wherein when the amplitude amount of the outer piston is equal to or greater than a predetermined value, the second urging force becomes equal to or less than the first urging force, and the second fluid passage is opened. Variable force damper. The first elastic means and the second elastic means have different spring constants,
The damping force adjusting means is
A valve body is provided at the tip of the first elastic means, a valve seat is provided in the second fluid passage, and a force acting on the valve body by the first urging force and the pressure of the fluid passing through the second fluid passage. And a second valve mechanism that opens the second fluid passage when balanced with,
The variable damping force damper according to claim 2, wherein the inner piston is provided with the second fluid passage, the first valve mechanism, and the second valve mechanism.

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