JPH0632130A - Suspension control device for vehicle - Google Patents

Abstract

PURPOSE:To constitute a suspension stroke speed sensor, and simplify installation work and a system by constituting a vertical relative displacement speed detecting means to detect vertical relative displacement speed between a sprung side and an unsprung side, of a coil installed in either one of a damping force variable damper and a piston rod and a magnet installed in the other thereof. CONSTITUTION:A magnet 7 to move vertically in a coil 6 arranged on the hollow part inner peripheral wall of a rod 32 of a damping force variable damper 1 is supported with the bottom part 2a of a cylinder 2. A suspension stroke speed sensor is constituted so that induced electromotive force in proportion to relative displacement speed between the cylinder 2 and a piston rod 3 is generated in the coil 6 by combining the coil 6 and the magnet 7 with each other and the output can be used as it is in damping force control as information on suspension stroke speed. When the number of turns of a coil 8 is set properly, coil output can be used as it is in the damping force control as information on vertical relative displacement speed between sprung side and an unsprung side without using an amplifying means such as an amplifier.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle suspension control device.

[0002]

2. Description of the Related Art The theory of a skyhook damper (a virtual model in which one wheel suspension is regarded as one degree of freedom and exerts damping in absolute space) is approximated by a damping force variable damper mounted at the actual vehicle suspension position. In order to improve the riding comfort by optimizing the vehicle body vibration, the damping force variable damper is used by using the vertical displacement speed information on the sprung and the vertical relative displacement speed (suspension speed) information between the sprung unsprung parts. Various suspension control devices for vehicles that control the damping force of the vehicle in real time have been researched and developed.
One of them is disclosed in JP-A-61-163011.

As a control law of a vehicle damping force variable damper using the skyhook damping theory, an on / off control law (ON / OFF control for switching between a high damping force characteristic and a low damping force characteristic) is used (the above-mentioned prior art). Belongs to this) and a continuous control law that has many damping force characteristics between the upper limit value of the high damping force characteristic and the lower limit value of the low damping force characteristic and continuously switches these. .

[0004]

In order to realize the switching control of the damping force variable damper using the above-mentioned skyhook damping theory, both the on / off control law and the continuous control law are sprung (vehicle body). It is necessary to obtain the vertical displacement speed and the vertical relative displacement speed between the sprung mass and the unsprung mass, that is, the suspension stroke speed. Conventionally, as a method for obtaining this suspension stroke speed, as shown in FIG. A suspension stroke sensor including a rod c, an arm d, a rotation axis e, and a sensor body f is attached across a suspension lower arm b, and a detection signal (suspension signal) of the suspension stroke sensor is differentiated to generate a suspension stroke speed. It is common to adopt a method of asking for. There is also a conventional sensor body f which directly outputs the suspension stroke speed as a detection signal. The vertical displacement speed on the spring has been generally used conventionally by integrating the detection signal of the vertical acceleration sensor h mounted near the mounting portion of the damping force variable damper g on the vehicle body.

As described above, conventionally, the sensor for detecting the suspension stroke speed is mounted separately from the damping force variable damper g so as to straddle between the sprung and unsprung parts. There is also a problem in terms of space, and there is a problem in that the system is complicated.

The present invention has as its main object to solve the above conventional problems.

[0007]

According to the present invention, the damping force characteristic of the damping force variable damper is turned on based on the information on the vertical displacement speed on the spring and the information on the vertical relative displacement speed between the sprung and unsprung as described above. In a control device for a vehicle suspension that is switched off or continuously, a detecting means for detecting a vertical relative displacement speed between the sprung and unsprung portions is provided in a cylinder of a damping force variable damper for the cylinder and the piston rod. It is characterized by being configured by a combination of a coil attached to either one and a magnet attached to the other.

[0008]

As described above, when the piston rod expands and contracts with respect to the cylinder, the magnet approaches and moves away from the coil to generate an induced electromotive force in the coil. The magnitude of its output depends on the relative speed between the cylinder and the piston rod. Since it is proportional to the product of the vertical relative displacement speed between the sprung and unsprung parts and the number of turns of the coil, the coil output can be output without using amplification means such as an amplifier by appropriately setting the number of turns of the coil. It can be directly used for damping force control as the vertical relative displacement velocity information between the lower part, and the construction and mounting work can be simplified, and the entire system can be simplified.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a damping force variable damper used in the present invention. This damping force variable damper 1 is
It comprises a cylinder 2 having a lower end attached to an unsprung member, and a piston rod 3 having an upper end attached to a sprung member and moving in the cylinder 2 in the axial direction.
Is composed of a main piston 31 whose outer peripheral surface is in sliding contact with the inner peripheral surface of the cylinder 2 and an internally hollow rod 32.

The main piston 31 is provided with an extension side main passage 31a and a contraction side main passage 31b.
The oil in the upper chamber 21 and the lower chamber 22 of the cylinder 2 partitioned by the main piston 31 passes through the extension side main passage 31a to the lower chamber 22 (when the piston rod extends) and the contraction side main passage 31b. Through the lower chamber 22
To the upper chamber 21 (when the piston rod is contracted), and a damping force is generated by the oil flow resistance at that time. An orifice 32 that connects the upper chamber 21 and the lower chamber 22 to each other through a hollow portion inside the rod 32.
a, a cylindrical rotary shutter 4 that controls opening / closing of the orifice 32a (or variably controls the opening area of the orifice) is rotatably fitted in the hollow portion of the rod 32, and rotates the shutter 4. A driving motor (including a speed reducer) 5 is installed in the hollow portion of the rod 32.

Reference numeral 6 denotes a coil provided on the inner peripheral wall portion of the lower portion of the hollow portion of the rod 32, and 7 is held on the bottom portion 2a of the cylinder 2 by a holding shaft 7a so as to face the inside of the coil 6 with a predetermined gap. It is a magnet, and the coil 6 and the magnet 7 constitute a suspension stroke speed sensor 8 for detecting the vertical relative displacement speed between the sprung part and the unsprung part. That is, piston rod 3 for cylinder 2
When the magnets expand and contract vertically, the magnets 7 move up and down with respect to the coil 6 and move away from and approach each other.
As a result, an induced electromotive force is generated in the coil 6. When the number of turns of the coil is N and the magnetic flux passing through the coil is φ, the induced electromotive force e is e = N (Δφ / Δt), and the induced electromotive force e
Is proportional to the product of the speed of magnetic flux change and the number of turns of the coil. Further, the direction of the induced electromotive force e is such that, when the magnetic flux decreases, the magnetic flux decreases and when the magnetic flux decreases, the induced electromotive force e decreases. Therefore, the induced electromotive force e is attached to the unsprung member 2 and the sprung member as described above. By mounting the magnet 7 and the coil 6 on the piston rod 3 supported, the induced electromotive force generated in the coil 6 becomes an output proportional to the vertical relative displacement speed between the sprung and unsprung parts, that is, the suspension stroke speed. , And the number of coil turns N
Since a large output can be obtained by increasing, it can be directly used for control as the suspension stroke speed information without being amplified by an amplifier or the like.

By incorporating the suspension stroke speed sensor for detecting the vertical relative displacement speed between the sprung and unsprung portions into the damping force variable damper as described above, the lower arm of the suspension and the upper portion thereof are provided as in the conventional device shown in FIG. Compared to the one with the suspension stroke sensor installed over the vehicle body, it is possible to greatly simplify the configuration and installation work, and it is extremely advantageous in terms of space, resulting in simplification of the entire system. I will get it.

Next, the damping force control of the suspension controller using the damping force variable damper 1 will be described with reference to FIGS. 2 and 3.
Will be described with reference to.

FIG. 2 shows an on / off control rule for switching the high damping force characteristic a and the low damping force characteristic b on / off as shown in FIG. 2 (A). The example to which 1 is applied is shown. In this case, the damper 1 of FIG.
The shutter 4 is rotated by the motor 5 and the orifice 32 is rotated.
It is assumed that a is controlled to be turned on and off.

FIG. 2B is a model diagram in which a single wheel model of the suspension is combined with a controller 10 for controlling the suspension. In this figure, M1 and K1 represent unsprung mass, that is, tire mass and spring constant. M2 is the mass on the spring, that is, the mass of the vehicle body, K2 is the spring constant of the suspension spring 11, and C is the damping coefficient of the damping force variable damper 1.
X0 is the vertical displacement of the road surface, X1 is the vertical displacement under the spring, X
2 represents the vertical displacement on the spring. Reference numeral 9 denotes a vertical acceleration sensor for detecting the vertical acceleration of the vehicle body. The vertical acceleration sensor 9 is the rod 3 of the damping force variable damper 1 as in the conventional case.
It is attached at a position in the vicinity of the attachment portion of the upper end portion to the vehicle body side.
As shown in FIG. 1, the suspension stroke speed sensor 8 is composed of a coil 6 and a magnet 7 and is incorporated in the damping force variable damper 1.

The vertical acceleration on the spring detected by the vertical acceleration sensor 9 is integrated by the integrating circuit 10a to become the vertical displacement speed on the spring. The vertical displacement speed and the suspension stroke speed detected by the suspension stroke speed sensor 8 are combined. Based on the information, the controller 10 compares the direction of the vertical displacement speed on the spring and the direction of the suspension stroke speed (the upward and downward displacement speed of the sprung is +, downward is +, and the suspension stroke speed is + in the extension direction). , The contraction direction is represented by a minus sign), and if the two speed directions are the same, the high damping force characteristic a is selected, and if they are different, the low damping force characteristic b is selected. Variable damping force damper 1
An output for switching the damping force characteristics of the motor 5 (see FIG. 1) is generated, and the shutter 4 is driven by the rotation of the motor 5.
Rotates to control opening / closing of the orifice 32a. When the orifice 32a is closed, the oil in the cylinder 2 passes only through the expansion main passage 31a and the contraction main passage 31b of the main piston 31 to the upper chamber 21 to the lower chamber 22 and from the lower chamber 22 to the upper chamber 21. As a result, the damping force characteristic a is relatively high, and when the orifice 32a is open, the main passages 31a on the expansion side and the contraction side are
Since oil flows from the upper chamber 21 to the lower chamber 22 and from the lower chamber 22 to the upper chamber 21 through the orifice 32a in addition to 31b, the damping force characteristic b becomes relatively low. In the above description, the high damping force and the low damping force are only relative and are not limited to specific numerical values, and may be set arbitrarily.

FIG. 3 is a damping force variable damper capable of continuously changing arbitrary damping force characteristics between the high damping force upper limit value C _H and the low damping force lower limit value C _S , for example, the damping force of FIG. Orifice 3 by shutter 4 in variable damper 1
A suspension control device using a continuous control law, which is capable of continuously variably controlling the opening area of 2a between fully closed (upper limit of high damping force) and fully open (lower limit of low damping force). The example to which the present invention is applied is shown.

In FIG. 3 (B), the suspension stroke speed sensor 8 is composed of the coil 6 and the magnet 7 shown in FIG. 1 and incorporated in the damping force variable damper 1 as in FIG. 2 (B). Other reference numerals that are the same as those in FIG. 2B represent the same components as those in FIG.

Also in the case of this continuous control law, the vertical displacement speed on the spring obtained by integrating the vertical acceleration on the spring detected by the vertical acceleration sensor 9 by the integrating circuit 10a, and the suspension detected by the suspension stroke speed sensor 8. 2 with stroke speed
Based on the two pieces of information, the controller 10 performs the calculation as shown in the figure to output the output for continuously changing and controlling the damping force characteristic to the motor 5 (see FIG. 1), and the rotation of the motor 5 causes the shutter 4 to rotate. The opening area of the orifice 32a is continuously and variably controlled to obtain the damping force characteristic as instructed by the controller 10. Since the calculation method of the controller 10 is well known in the art, detailed description thereof will be omitted.

As described above, even in the continuous control law of the damping force variable damper, the suspension stroke speed sensor 8 including the magnet 7 and the coil 6 is supported by the cylinder 2 and the piston rod 3, respectively, and the damping force variable damper is supported. As a result of being incorporated into the No. 1 unit, compared to the conventional device shown in FIG.
It is advantageous in terms of space by simplifying the configuration and mounting work, and the function and effect that the signal of the suspension stroke speed sensor 8 can be directly used for control as the suspension stroke speed information and the overall system can be simplified. Is something that can be done.

FIG. 4 is a block diagram of the controller 10 shown in FIGS. 2B and 3B.

That is, the vertical acceleration signal detected by each vertical acceleration sensor 9 is integrated by the integrating circuit 10a to become a signal (voltage signal) corresponding to the vertical displacement speed, and the signal is supplied to the A / D converter 13a via the multiplexer 12a. Is input to the microcomputer 14, is converted into a digital signal here, and is input to the microcomputer 14. Further, a signal (voltage signal) corresponding to the electromotive force generated in the coil 6 of the suspension stroke speed sensor 8 incorporated in each damping force variable damper 1, that is, the suspension stroke speed, is sent to the A / D converter via the multiplexer 12b.
The signals are input to the converter 13b, converted into digital signals respectively, and input to the microcomputer 14.
The microcomputer 14 basically comprises an interface circuit 14a, an arithmetic processing circuit 14b, and a storage device 14c, and corresponds to a digital signal corresponding to the vertical displacement speed output by the A / D converters 13a and 13b and a suspension stroke speed. Interface circuit 14
When it is input to a, the arithmetic processing circuit 14b makes a change judgment of the damping force characteristic of each damping force variable damper 1 as described in the explanation of FIG. 2B or FIG. The determination result is stored in the storage device 14c, and a damping force control signal is issued to each drive circuit 15 via the interface circuit 14a, and a control current is supplied from each drive circuit 15 to the motor 5 of each damper 1 to reduce the damping force. The characteristics are variably controlled independently for each damping force variable damper.

The variable damping force damper 1 to which the present invention is applied.
1 is not limited to the embodiment shown in FIG. 1, but, for example, a vertically sliding shutter is used instead of the rotary shutter 4, or a plunger device that vertically moves by electromagnetic force is used instead of the motor 5 as an actuator. The present invention can be applied to a damper having an arbitrary mechanism capable of variably controlling the damping force. Furthermore, FIG. 1 shows an example in which a suspension stroke speed sensor with a built-in damper is configured by a combination of a coil provided on the piston rod 3 side and a magnet supported on the cylinder 2 side. The inner peripheral wall of the lower portion of the hollow portion can be used as it is as a coil mounting portion, and there is an advantage that the structure is simple and the fitting is very good, but the present invention is not limited to the above. It is also possible to support each of them and combine them.

[0025]

As described above, according to the present invention, the sprung and unsprung top and bottom relative to each other necessary for realizing the continuous control law and the on / off control law of the vehicle damping force variable damper using the skyhook theory. The displacement velocity is measured by a suspension stroke velocity sensor that is a combination of a coil incorporated in the damping force variable damper and a magnet that moves up and down relative to the coil. The electric power can be used as it is as suspension stroke speed information for damping force control.In addition to the damping force variable damper, a suspension stroke sensor that detects vertical relative displacement across the lower arm of the suspension and the vehicle body is installed and its detection signal Compared with the conventional device that differentiates the suspension stroke speed information to obtain the suspension stroke speed information, the configuration and installation work are significantly simplified and the overall system is simplified. That can be achieved, and as it can be achieved also to improve the durability of the suspension stroke velocity sensor, but that can result in practical effect considerable.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an example of a damping force variable damper used in the present invention.

2A and 2B show a first example of a vehicle suspension control device using the variable damping force damper of FIG. 1, in which FIG. 2A is a damping force characteristic diagram of the variable damping force damper, and FIG. It is a model diagram which combined the controller which controls the wheel model with that.

3A and 3B show a second example of a suspension control device for a vehicle using the variable damping force damper of FIG. 1, where FIG. 3A is a damping force characteristic diagram of the variable damping force damper, and FIG. It is a model diagram which combined the controller which controls the wheel model with that.

FIG. 4 is a block diagram of a controller of a vehicle suspension control device that performs the control shown in FIGS. 2 and 3.

FIG. 5 is a perspective view showing a mounting structure example of a suspension stroke sensor in a conventional suspension control device.

[Explanation of symbols]

 1 Damping force variable damper 2 Cylinder 3 Piston rod 4 Shutter 5 Motor 6 Coil 7 Magnet 8 Suspension speed sensor 9 Vertical acceleration sensor 10 Controller 31 Main piston 32 Rod 32a Orifice

Claims (1)

[Claims] 1. A damping force variable damper capable of switching the damping force characteristics on / off or continuously is used to obtain information on the vertical displacement speed on a spring and information on the vertical relative displacement speed between unsprung and unsprung springs. Based on the above, in a control device for a vehicle suspension equipped with a controller for switching control of the damping force characteristic of the damping force variable damper, a means for detecting a vertical relative displacement speed between the sprung and unsprung portions is used as a means for detecting the damping force variable damper. A vehicle suspension control device comprising a combination of a coil attached to one of the cylinder and the piston rod and a magnet attached to the other in the cylinder.