JPH07100452B2 - Steering force control device for power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a power steering system including a reaction force mechanism that supplies a control pressure according to a vehicle speed or the like and changes a steering wheel torque according to the vehicle speed or the like. The present invention relates to a steering force control device.

<Prior Art> It is known that a control pressure proportional to a vehicle speed or the like is introduced into a reaction force mechanism to control the steering force of a power steering device according to the vehicle speed or the like. In this type of device, the oil pressure introduced into the reaction force mechanism is controlled by using the pressure oil in the high pressure line connecting the power steering device and the supply pump.

<Problems to be Solved by the Invention> Generally, this type of control device lowers the oil pressure applied to the reaction force mechanism during low-speed traveling that requires steering pressure, and conversely increases it at high speed where steering pressure is almost unnecessary. There is a need to.

Conventionally, control of the hydraulic pressure applied to this reaction force mechanism is controlled by an electromagnetic pressure control valve based on a signal such as vehicle speed, regardless of the steering pressure. As a result, the characteristic of the manual torque-gear generated pressure is that the characteristic during high-speed traveling only moves in parallel to the characteristic during low-speed traveling, and the inclination of the characteristic during high-speed traveling cannot be changed freely. Therefore, there is a problem that the steering force does not change much even if the steering wheel is turned while the reaction force hydraulic pressure is high. Ideally, the characteristics should be such that the inclination during high-speed traveling is large.

In view of the above conventional problems, the present invention clarifies the change in the steering force by setting the ideal torque-gain generated pressure characteristic during high-speed traveling to an ideally large inclination.

<Means for Solving Problems> The present invention is directed to a servo valve that is operated based on relative rotation between an input shaft and an output shaft to control supply and discharge of pressure oil to and from a power cylinder, and a handle torque according to a vehicle speed. In a steering force control device for a power steering apparatus having a reaction force mechanism that changes the flow rate of a constant flow rate of pressure oil discharged from a supply pump to the servo valve and the reaction force mechanism. , An electromagnetic throttle valve that controls the diversion ratio of the diversion control valve according to the vehicle speed to increase the flow rate to the reaction force mechanism side and decreases the flow rate to the servo valve side as the vehicle speed increases, and to the reaction force mechanism. The first for squeezing the shunted pressure oil and releasing it to the low pressure side
A fixed throttle and a second fixed throttle provided in a passage that communicates the servo valve side and the reaction mechanism are provided.

<Operation> According to the present invention, the pressure oil having a constant flow rate discharged from the supply pump is diverted by the shunt control valve and the electromagnetic throttle valve at a flow rate ratio according to the vehicle speed. That is, as the vehicle speed increases, the flow rate to the reaction mechanism is increased and the flow rate is controlled to the servo valve and the reaction mechanism so as to decrease the flow rate to the servo valve side. By controlling the oil with the first fixed throttle, a pressure corresponding to the vehicle speed is generated in the reaction force chamber. At the same time, the flow rate of the pressure oil shunted to the servo valve side is reduced as the vehicle speed increases, so the sensitivity of the servo valve becomes dull, and in combination with the reaction force pressure that increases with the increase of the vehicle speed, The stability can be improved. Further, the pressure oil on the servo valve side is guided to the reaction force mechanism side via the second fixed throttle according to the increase in the gear generation pressure, and the reaction force hydraulic pressure is controlled according to the gear generation pressure.

<Example> An example of the present invention will be described below with reference to the drawings. In FIG. 1, 11 is a housing main body which is the main body of the power steering apparatus, and 12 is a valve housing fixed to the housing main body 11. A pinion shaft (output shaft) 21 is provided in the housing body 11 and the valve housing 12 via a pair of bearings 13 and 14.
Is rotatably supported, and the pinion shaft 21 has rack teeth 22 of a rack shaft 22 slidable in a direction intersecting with the pinion shaft 21.
a is in mesh. The rack shaft 22 is connected to a piston of a power cylinder (not shown), and both ends of the rack shaft 22 are connected to steering wheels via a required steering link mechanism.

A control valve mechanism 30 is housed in the hole of the valve housing 12. The control valve mechanism (servo valve) 30 includes a rotary valve member 31 integrally formed with the input shaft 23 as a steering shaft, and a sleeve valve concentrically and relatively rotatably fitted to the outer periphery of the rotary valve member 31. The member 32 is the main constituent member. The rotary valve member 31 is flexibly connected to the pinion shaft 21 via a torsion bar 24, one end of which is connected to an input shaft 23 which is integral with the rotary valve member 31. Further, on the outer periphery of the rotary valve member 31,
Although not shown, a plurality of lands extending in the axial direction thereof and a groove are formed at equal intervals, and a communication passage 37 communicating from the groove bottom to the inner peripheral portion is formed. The input shaft 23 is provided with a passage 39 that connects the inner peripheral portion and the low pressure chamber 38 in the valve housing 12. On the other hand, on the inner circumference of the sleeve valve member 32, a plurality of lands extending in the axial direction and grooves are formed at equal intervals, and distribution holes 40, 41 are provided which open from the grooves to the outer circumference of the sleeve valve member 32. ing. Supply port 35
When the control valve is in the neutral state, the pressure fluid supplied from the flow passages evenly flows into the grooves on both sides of the land portion, and the communication passage 37 and the passage 39
Through the low pressure chamber 38 to the discharge port 36. In this case, the power cylinders are not operated because both distribution ports 33, 34 have low pressure and equal pressure. When the control valve is deviated from the neutral state, pressure oil is supplied to one of the distribution holes 40 or 41 through the supply port 35, and the fluid discharged from the power cylinder flows into the other distribution hole 41 or 40, and the communication is continued. The gas is discharged to the discharge port 36 via the passage 37, the passage 39, and the low pressure chamber 38.

The reaction force mechanism is as follows. As shown also in FIG. 2, the rotary valve member 31 has a protrusion 50 that is formed at the end on the pinion shaft 21 side and protrudes radially to both sides.
The pinion shaft 21 corresponding to the above is formed with a fitting groove 51 into which the protrusion 50 is loosely fitted so as to be rotatable about the axis of the input shaft 23 by several angles. A tapered engagement groove 52 is formed on the outer peripheral surface of the protrusion 50, and in a neutral state of the control valve, an insertion hole 53 is formed in the pinion shaft 21 at a position corresponding to the engagement groove 52 in the radial direction. Has been done. A plunger 54 is inserted into the insertion hole 53 so as to be slidable in the radial direction, and an annular groove 55 is formed to guide the working oil to the rear portion of the plunger 54. The insertion hole 53 and the annular groove 55 form a reaction force chamber 56. Reference numeral 58 is a port for introducing pressure fluid from a pump controlled according to vehicle speed and the like, and 57 is a passage for connecting the port 58 and the annular groove 55.

The reaction mechanism having the above structure is a so-called radial system, but may be a thrust system having a structure in which a reaction force is applied in the axial direction.

Reference numeral 60 denotes a supply pump driven by an automobile engine, and 61 is a flow rate control valve for controlling the pressure oil discharged from the supply pump 60 to a constant flow rate Q. This flow control valve 61
Is operated according to the front-rear pressure of the metering orifice 62 and the front-rear pressure of the metering orifice 62, and the bypass passage 63 communicating with the low-pressure side so as to always maintain the front-rear pressure constant.
The bypass valve 64 controls the opening of the valve.
The flow rate control valve 61 is not necessary when the supply pump 60 discharges a constant flow rate of a constant speed motor drive type.

Reference numeral 80 is a diversion control valve connected to the high pressure side of the flow control valve 61. This diversion control valve 80 has a port 80a for introducing pressure oil of a flow rate QG into the supply port 35 of the servo valve via the passage 45,
The reaction force mechanism has an introduction port 58 having a port 80b for introducing pressure oil having a flow rate QG through the passage 46, and the constant flow rate QG and QR are controlled to divide the flow rate QG, QR according to the vehicle speed or the like. The pressure oil is controlled to a flow rate QR according to the vehicle speed by an electromagnetic throttle valve 90 that is controlled according to the vehicle speed and the like, and this flow rate QR is guided to the flow dividing control valve 80,
A spool that is axially moved by the differential pressure across the electromagnetic throttle valve 90.
It is equipped with 81. Therefore, by changing the opening degree of the electromagnetic throttle valve 90 according to the vehicle speed, the flow rate QR applied to the reaction mechanism is supplied to the servo valve in reverse so as to increase as the vehicle speed increases as shown in FIG. The diversion rate is controlled so that the flow rate QG decreases as the vehicle speed increases.

As shown in FIG. 3, the electromagnetic throttle valve 90 has a throttle passage 91.
And a throttle valve rod 93 for adjusting the opening degree of the throttle passage 91, and a solenoid 92 for axially displacing the throttle valve rod 93 in the axial direction by supplying a current value that changes according to a signal such as a vehicle speed. . The solenoid throttle valve 90 is supplied with a current value V corresponding to the vehicle speed or the steering angle of the steering wheel to the solenoid 92, changes the opening of the solenoid throttle valve 90 according to the current value V, and controls the flow rate QR. Is.

Further, the first fixed throttle 70 communicating with the low pressure side is connected to the passage 46 communicating with the port 80b of the diversion control valve 80 and the introduction port 58 of the reaction force mechanism.

Further, the passage 45 communicating with the port 80a of the flow dividing control valve 80 and the supply port 35 of the servo valve and the passage on the reaction force mechanism side.
A bypass passage 47 is provided between the bypass passage 47 and
The second fixed diaphragm 71 is provided in the.

Next, the operation of the above configuration will be described. The flow rate control valve 61 controls the pressure oil discharged from the supply pump 60 to a constant flow rate Q. The pressure oil controlled to this constant flow rate Q is a diversion control valve.
Flow rate QG to servo valve side and flow rate QR to reaction force mechanism by 80
And shunt control.

The divided flow rate QR to the reaction force mechanism is controlled by the electromagnetic throttle valve 90
As the vehicle speed V increases from V1 to V4, QR1
~ Increase in proportion to AR4. The flow rate QG on the servo valve side is inversely proportionally divided according to the change in the divided flow rates QR1 to QR4. Further, the flow rate QR diverted to the reaction force mechanism side is drained to the low pressure side via the first fixed throttle 70.

As a result, when the vehicle speed is low, the flow rate QR controlled by the electromagnetic throttle valve 90 is drained with almost no resistance from the first fixed throttle 70, so that the reaction force hydraulic pressure PR becomes low and the steering shaft 24 rotates when the steering wheel is operated. , The plunger 54 is easily pushed up, the sleeve valve member 32 and the rotary valve member 31 rotate relative to each other, and the gear generation pressure against the manual torque TM is increased.
The change in PG has the characteristics shown by the solid line in Fig. 7, and steering wheel operation at stationary and low speed becomes light.

When the vehicle speed becomes high, the shunt flow rate QR to the reaction mechanism side increases to QR1 to QR4 by the electromagnetic throttle valve 90 controlled according to the vehicle speed. Due to the increase in the flow rate QR, the reaction force hydraulic pressure PR is increased by the action of the first fixed throttle 70, whereby the plunger 54 is pressed against the engagement groove 52 with a force corresponding to the reaction force hydraulic pressure PR, and the sleeve valve member 32 and the rotary The manual torque for relatively rotating the valve member 31 increases in accordance with the vehicle speed, and the steering wheel operation becomes heavy.

On the other hand, the shunt flow rate QG supplied to the servo valve decreases in inverse proportion to the shunt flow rate QR to the reaction force mechanism side when the vehicle speed becomes high, so the sensitivity of the servo valve becomes dull at high speeds,
Handle operation becomes heavy.

Further, at a certain vehicle speed, when the gear generation pressure PG rises in accordance with the steering wheel operation, the flow rate g corresponding to the gear generation pressure from the servo valve side passage 45 to the reaction force mechanism side passage 46 via the second fixed throttle 71. Pressure oil flows from the bypass passage 47. Therefore, the flow rate QR on the reaction mechanism side + bypass flow rate g = control flow rate QC
Is controlled as shown in FIG. 5 according to the reaction force hydraulic pressure PR controlled by the electromagnetic throttle valve 90 and according to the gear generation pressure PG. Therefore, when the handle is operated at high speed, the reaction force hydraulic pressure PR
Is controlled by the above-mentioned control flow rate QC = QR + g as shown in FIG. 6, and the characteristic of the manual torque-gear generated pressure is greatly inclined as shown by the dotted line in FIG. 7 to make the feeling of steering feel clear.

<Effects of the Invention> As described above, according to the present invention, the flow rate of pressure oil from the supply pump to the reaction force mechanism side is increased as the vehicle speed increases by the flow dividing control valve and the electromagnetic throttle valve. The flow is divided into the servo valve and the reaction force mechanism so as to reduce the flow rate to the servo valve side, and the pressure oil divided in the reaction force mechanism is throttle-controlled by the first fixed throttle communicating with the low pressure side.
Since the pressure oil is introduced from the servo valve side to the reaction force mechanism side via the second fixed throttle in response to the increase in the gear generation pressure, the reaction force pressure of the reaction force mechanism is increased during high speed traveling. Higher-speed stability can be significantly improved compared to the conventional one in combination with the decrease in sensitivity due to the decrease in the flow rate to the servo valve, and the reaction force pressure can be adjusted to the optimum pressure according to the vehicle speed without being affected by the steering pressure. Control, and second
By the action of the fixed throttle, there is an effect that the feeling of handling when steering at high speed is increased and the steering stability is improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a power steering apparatus showing an embodiment of the present invention with a hydraulic oil system diagram, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is an electromagnetic throttle. Fig. 4 is a cross-sectional view of the main part of the valve, Fig. 4 is a graph showing the change in the divided flow rate QR controlled by the vehicle speed, Fig. 5 is a graph showing the change in the control flow rate QC due to gear generation pressure, and Fig. 6 is the gear generation pressure FIG. 7 is a curve diagram of the steering characteristic, showing a change in the reaction force hydraulic pressure due to. 21 …… Pinion shaft, 23 …… Input shaft, 47 …… Bypass passage, 56 …… Reaction chamber, 80 …… Diversion control valve, 90 …… Electromagnetic throttle valve, 70 …… First fixed throttle, 71 …… Second fixed aperture.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-51-132541 (JP, A) JP-A-52-106528 (JP, A) JP-A-52-109230 (JP, A) JP-A-53- 87433 (JP, A) JP 53-4928 (JP, A) Actually opened 61-44365 (JP, U) Actually opened 52-116837 (JP, U)

Claims (1)

[Claims] 1. A servo valve which is operated based on relative rotation between an input shaft and an output shaft to control supply and discharge of pressure oil to and from a power cylinder, and a reaction force mechanism which changes a steering wheel torque according to a vehicle speed. In a steering force control device of a power steering device, a diversion control valve that diverts a constant flow rate of pressure oil discharged from a supply pump to the servo valve and a reaction mechanism, and diverts the diversion control valve according to a vehicle speed. The electromagnetic throttle valve that controls the flow shunt ratio to increase the flow rate to the reaction force mechanism side and decreases the flow rate to the servo valve side as the vehicle speed increases, and the pressure oil shunted to the reaction force mechanism is throttled to reduce the low pressure. A steering force control device for a power steering system, comprising: a first fixed throttle for releasing to the side; and a second fixed throttle provided in a passage that communicates the servo valve side with a reaction mechanism.