JP2003170847A - Power steering device - Google Patents

Abstract

(57) [Problem] To provide a power steering device in which energy loss is minimized by controlling a control flow rate QP according to a steering state of a moving body such as a vehicle. SOLUTION: An orifice of a flow control valve V is a variable orifice a for controlling an opening degree according to excitation or non-excitation of a solenoid SOL, and the solenoid of the variable orifice a is excited or non-excited according to a steering condition. A variable resistance control mechanism C for excitation or the like is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering system equipped with a flow rate control valve for controlling a flow rate introduced to a power cylinder side.

[0002]

2. Description of the Related Art A flow control valve incorporated in a power steering device of this type incorporates a spool in its main body, and one end of this spool is made to face one pilot chamber which is always in communication with a pump port, and the other end of the spool. Is exposed to the other pilot chamber with a spring interposed. A fixed orifice is provided on the downstream side of the one pilot chamber, and the pressure oil is guided to the steering valve that controls the power cylinder via the fixed orifice.

On the other hand, the pressure on the upstream side of the orifice is set as the pilot pressure of the one pilot chamber, and the pressure on the downstream side is set as the pilot pressure of the other pilot chamber, and the moving position of the spool is determined by the pressure balance between the two pilot chambers. I'm trying to control. Depending on the moving position of the spool, the discharge amount of the pump is divided into a control flow rate QP that guides the steering valve and a return flow rate QT that is returned to the tank or the pump. And, the spool keeps the differential pressure before and after the fixed orifice constant,
On the steering valve side that controls the power cylinder,
A constant control flow rate QP is always supplied.

[0004]

In the conventional device as described above, the control flow rate QP is always constant from the flow rate control valve.
Will be supplied to the steering valve side that controls the power cylinder. In other words, this control flow rate Q
P always supplies a constant control flow rate QP to the steering valve side regardless of the vehicle speed and steering conditions. However, regardless of the vehicle speed and steering conditions,
When the control flow rate QP is specified, for example, when the flow rate QM required by the power cylinder is QP> QM, the surplus flow rate must be returned to the tank via the steering valve.

Returning the surplus flow rate to the tank via the steering valve as described above increases the pressure loss of the circuit. In other words, the pump must continue to consume the driving torque corresponding to this pressure loss. Therefore, the greater the driving torque of the pump, the more energy is consumed.

Moreover, since the control flow rate QP is set in accordance with the maximum required flow rate of the power cylinder, in most cases, some surplus flow rate is returned to the tank at present. Therefore, in this conventional device,
There was a problem that the energy loss became large.
An object of the present invention is to provide a power steering device in which energy loss is minimized by controlling the control flow rate QP according to the steering state of a moving body such as a vehicle.

[0007]

According to the present invention, a spool is incorporated in a main body, one end of the spool is made to face one pilot chamber which is always in communication with a pump port, and the other end of the spool is provided with a spring. An orifice is provided on the downstream side of the one pilot chamber so as to face the other pilot chamber, and the pressure oil is guided to the steering valve controlling the power cylinder through the orifice, while the pressure on the upstream side of the orifice is adjusted to the one side. Pilot pressure in the pilot chamber, the downstream pressure is the pilot pressure in the other pilot chamber, the spool movement position is controlled by the pressure balance between both pilot chambers, and the pump discharge amount A control flow rate QP that guides the air to the steering valve side, and a return flow rate QT that recirculates to the tank or pump. To assume the power steering apparatus in the configuration for dispensing.

Based on the above apparatus, the first invention uses an orifice as a variable orifice whose opening is controlled according to the exciting current of the solenoid, and controls the exciting current of the solenoid according to the steering condition. The feature is that a variable resistance control mechanism is provided.

A second aspect of the present invention is characterized in that the resistance value of the variable resistance control mechanism is maximized in the neutral state of the steering wheel, and the resistance value of the variable resistance control mechanism is reduced in a situation other than the neutral position. Have. The third invention is
A feature is that a cam that rotates in accordance with the rotating operation of the steering wheel is provided, and the variable resistance control mechanism is operated by this cam. The fourth invention is characterized in that a variable resistance control mechanism for varying the resistance value is provided in conjunction with an operating system such as a power cylinder.

[0010]

1 to 3 show a first embodiment. Then, first, the overall configuration of the power steering apparatus will be described with reference to FIG. A pump P is integrally incorporated in the main body B together with the spool 1 of the flow control valve V.

The spool 1 has one end facing the one pilot chamber 2 and the other end facing the other pilot chamber 3. The one pilot chamber 2 is always in communication with the pump P via the pump port 4. A spring 5 is interposed in the other pilot chamber 3.
The two pilot chambers 2 and 3 thus configured communicate with each other via the variable orifice a, and the variable orifice a has a configuration in which the opening degree is controlled according to the excitation / non-excitation of the solenoid SOL. There is.

That is, one pilot chamber 2 communicates with the inflow side of the steering valve 9 for controlling the power cylinder 8 via the flow path 6 → the variable orifice a → the flow path 7. The other pilot chamber 3 communicates with the inflow side of the steering valve 9 via the flow passage 10 and the flow passage 7. Therefore, the two pilot chambers 2 and 3 are
The variable orifice a is communicated with, so that the pressure on the upstream side of the variable orifice a acts on one pilot chamber 2 and the pressure on the downstream side acts on the other pilot chamber 3. The variable orifice a is configured to keep its opening large in the excited state and keep it small in the non-excited state.

The spool 1 maintains a position where the acting force of one pilot chamber 2 and the acting force of the other pilot chamber 3 are balanced, but at the balanced position,
The opening degree of the pump port 4 and the tank port 11 is determined. If the pump drive source 12 composed of an engine or the like is stopped, pressure oil is not supplied to the pump port 4. If pressure oil is not supplied to the pump port 4, no pressure is generated in both pilot chambers 2 and 3, so the spool 1 maintains the normal position shown by the action of the spring 5.

When the pump P is driven from the above state and pressure oil is supplied to the pump port 4, a flow is made to the variable orifice a, so that a pressure loss occurs there. Due to the action of this pressure loss, a pressure difference is generated between the pilot chambers 2 and 3, and the spool 1 moves against the spring 5 in accordance with the pressure difference to maintain the balance position. By moving the spool 1 against the spring 5 in this way,
The opening of the tank port 11 is increased, but according to the opening of the tank port 11 at this time, the steering valve 9
The distribution ratio of the control flow rate QP guided to the side and the return flow rate QT recirculated to the tank T or the pump P is determined. In other words, according to the opening of the tank port 11, the control flow rate QP
Will be decided.

As described above, the control flow rate QP is controlled in accordance with the opening degree of the tank port 11 determined by the moving position of the spool 1, which means that the control flow rate QP is eventually changed in accordance with the opening degree of the variable orifice a. It will be decided. Because
The moving position of the spool 1 is determined by the pressure difference between the pilot chambers 2 and 3, and this pressure difference is determined by the opening of the variable orifice a.

Therefore, in order to control the control flow rate QP according to the steering condition, it is sufficient to control the opening of the variable orifice a, that is, the exciting current of the solenoid SOL. This is because the variable orifice a keeps its opening large when the exciting current of the solenoid SOL is large, and keeps its opening small when the exciting current is small.

It is the variable resistance control mechanism C shown in FIG. 2 that controls the exciting current of the solenoid SOL. That is, the variable resistance control mechanism C includes the cam 13 and
This cam 13 is linked to the steering wheel 14,
The cam 13 is turned by turning the steering wheel 14.
I also try to rotate. Cam 13 as above
The notch 13a is formed in the notch 1a.
3a corresponds to the roller 15 of the variable resistance control mechanism C when the steering wheel 14 is in the neutral position.

A rod 16 is provided on the roller 15, and a solenoid SOL is attached to the tip of the rod 16.
A variable resistor 17 for controlling the exciting current is provided. When the roller 15 coincides with the cutout portion 13a, that is, when the steering wheel 14 is in the neutral position, the resistance value of the variable resistor 17 becomes maximum, and when the roller 15 is in a position other than the cutout portion 13a. That is, the resistance value of the variable resistor 17 becomes small when the steering wheel 14 is set to a position other than the neutral position. In addition, the cam 13, the roller 15, the rod 1
6 and the variable resistor 17 constitute a variable resistance control mechanism.

Now, when the steering wheel 14 is in the neutral state, the resistance value of the variable resistor 17 is maximized while the exciting current is minimized, so that the opening of the variable orifice a is reduced. When the steering wheel 14 is turned to a position other than the neutral position, the resistance value of the variable resistor 17 decreases, but the exciting current increases, so that the opening of the variable orifice a increases. As described above, since the opening of the variable orifice a is small at the neutral position of the steering wheel 14 that does not require a large flow rate with respect to the power cylinder 8, the flow rate supplied to the steering valve 9 is reduced at this time. Therefore, the energy loss can be suppressed to a small extent as the supply flow rate decreases. Further, when the steering wheel 14 is turned off, the opening of the variable orifice a is increased accordingly and an appropriate flow rate is supplied to the power cylinder 8 side.

The relationship between the steering angle θ and the variable orifice a is as shown in FIG. That is, even if the exciting current of the solenoid SOL is the minimum, the variable orifice a is kept small. Further, the opening is kept small even when the steering wheel 14 is rotated near the neutral position. This considers the play in the vicinity of the neutral position of the steering wheel 14. Further, when the steering wheel 14 is rotated by a certain angle or more, the opening degree of the variable orifice a is gradually increased. The inclination of the graph when this opening becomes large depends on the shape of the cutout portion 13a.

Reference numeral 18 in the drawing denotes a slit formed at the tip of the spool 1. Even when the spool 1 is at the position shown in the drawing, one pilot chamber 2 is connected to the flow path 7 through the slit 21. We always try to communicate. In other words, even when the spool 1 is in the illustrated state and the flow path 6 is closed, the discharge oil of the pump P is supplied to the steering valve 9 side through the slit 18. ing. As described above, the reason why the pressure oil is supplied to the steering valve 9 side is for the purpose of preventing seizure of the entire apparatus, preventing disturbance such as kickback, and ensuring responsiveness, although the flow rate is minute. Because.

The second embodiment shown in FIG. 4 is a cam 13
Two notches 13a and 13b are formed on the
Others are exactly the same as the first embodiment. The two notches 13a and 13b are, for example, 1
One formed by shifting the phase by 80 degrees, one notch 13a corresponds to the neutral position of the steering wheel 14, and the other notch 13b corresponds to the full rotation position of the steering wheel 14. Is. In addition,
The positions of the cutouts 13a and 13b are determined by how the respective steering characteristics are set. In other words, the positions of the notches 13a and 13b may be specified according to the desired steering characteristic.

FIG. 5 shows the variable resistance control mechanism of the third embodiment, but the configuration other than this variable resistance control mechanism C is exactly the same as that of the first embodiment. The variable resistance control mechanism C of the third embodiment is linked to the shaft 19 of the power cylinder 8, and
That is, the steering wheel 14 is in a neutral state. That is, the shaft 19 is connected to the linking rod 20 that moves integrally therewith, and the holding member 22 that holds the movable contact 21 is provided at the tip of the linking rod 20, and the linking members 24 and 26 are provided on both sides thereof. Are arranged. Further, a variable resistor 23 that is movable relative to the holding member 22 is provided, and the variable resistor 23 is arranged so as to move in synchronization with a linking member 27 fixed to the linking member 26.

Therefore, as in the first embodiment, when the power cylinder 8 is in the neutral state, the resistance value of the variable resistor 23 increases and the exciting current of the solenoid SOL decreases, so that the variable orifice a is opened. The degree becomes smaller.
When the power cylinder 8 is displaced to a position other than the neutral position, the linkage rod 20 is also displaced synchronously. Specifically, when the shaft 19 moves leftward in the drawing, the linkage member 24 is pushed to move the working contact 21. Is displaced in the direction in which the resistance value of the variable resistor 23 decreases. On the contrary, when the shaft 19 moves to the right in the figure, the linking member 26 is pushed, so the linking member 27 integrated with this, that is, the variable resistor 23 also moves to the right, and the variable contact 21 changes the resistance value of the variable resistor 23. Is displaced in the direction of decreasing. When the variable contact 21 is displaced in this way, the exciting current of the solenoid SOL increases, and the opening of the variable orifice a also increases.

As described above, since the opening of the variable orifice a is reduced at the neutral position of the steering wheel 14 which does not require a large flow rate with respect to the power cylinder 8, energy loss is reduced as in the first embodiment. It can be kept small. Further, when the power cylinder 8 is displaced, the opening degree of the variable orifice a is increased accordingly, and an appropriate flow rate is supplied to the power cylinder 8 side. In the third embodiment, the link rod 20 is connected to the shaft 19 of the power cylinder 8, but it is natural that the link rod 20 may be linked to any portion of the operating system.

[0026]

According to the inventions of the first to fourth aspects, the control flow rate QP can be controlled according to the steering condition. Therefore,
Energy saving control can be performed by properly securing the control flow rate QP. Moreover, since the variable resistance control mechanism is configured to energize or de-energize the solenoid, the overall structure is greatly simplified.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a first embodiment.

FIG. 2 is a schematic view showing a variable resistance control mechanism of the first embodiment.

FIG. 3 is a graph showing control characteristics.

FIG. 4 is a schematic diagram showing a variable resistance control mechanism of a second embodiment.

FIG. 5 is a schematic diagram showing a variable resistance control mechanism of a third embodiment.

[Explanation of symbols]

B body QP control flow rate QT return flow rate 1 spool 2 One pilot room 3 The other pilot room 4 pump ports P pump SOL solenoid Variable orifice 8 power cylinders 9 Steering valve T tank 13 cams 14 Steering wheel C variable resistance control mechanism

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3D033 EB09                 3H106 DA05 DA35 DB02 DB12 DB23                       DB32 DC09 DD03 EE22 EE34                       FA01 KK03 KK17

Claims (4)

[Claims] 1. A spool is incorporated in a main body, one end of the spool is made to face one pilot chamber which is always in communication with a pump port, and the other end of the spool is made to face another pilot chamber in which a spring is interposed. An orifice is provided on the downstream side of the one pilot chamber, and the pressure oil is guided to the steering valve for controlling the power cylinder through the orifice, while the pressure on the upstream side of the orifice is set as the pilot pressure of the one pilot chamber, The pressure on the downstream side is used as the pilot pressure of the other pilot chamber, the movement position of the spool is controlled by the pressure balance of both pilot chambers, and the discharge amount of the pump is guided to the steering valve side according to the movement position. Power supply configured to distribute the flow rate QP and the return flow rate QT that is returned to the tank or pump. In the tearing device, the orifice is a variable orifice that controls the opening according to the exciting current of the solenoid, and according to the steering situation,
A power steering device provided with a variable resistance control mechanism for controlling an exciting current of a solenoid. 2. The power steering apparatus according to claim 1, wherein the resistance value of the variable resistance control mechanism is maximized in the neutral steering state, and the resistance value is gradually reduced in a situation other than the neutral position. 3. The power according to claim 1, wherein the variable resistance control mechanism is provided with a cam that rotates in response to a rotating operation of the steering wheel, and the resistance value of the variable resistance control mechanism is controlled by this cam. Steering device. 4. The power steering apparatus according to claim 1, further comprising a variable resistance control mechanism for controlling a resistance value in association with an operating system such as a power cylinder.