JPH0624301Y2 - Steering force control device for power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> 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 at low speed traveling that requires steering pressure, and conversely raises it at high speed where almost no steering pressure is required. 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 conventional problems described above, the present invention clarifies the change in the steering force by setting the ideal characteristic of the torque-gear generated pressure during high-speed traveling to a large ideal slope.

<Means for Solving Problems> The present invention is directed to a servo valve that controls the supply and discharge of pressure oil to and from a power cylinder that is operated based on the relative rotation of an input shaft and an output shaft, and a handle according to the vehicle speed. In a steering force control device for a power steering device equipped with a reaction force mechanism that changes torque, a constant flow rate of pressure oil discharged from a supply pump is supplied to a vehicle speed by an electromagnetic throttle valve whose throttle area is changed according to the vehicle speed. Flow control valve that divides into the servo valve and the reaction force mechanism so that the flow rate divided into the reaction force mechanism increases as the temperature rises, and the pressure oil that is divided into the reaction force mechanism is squeezed to the low pressure side. A first fixed throttle for escaping, and a second fixed throttle provided in a passage that connects an oil passage from the diversion control valve to the servo valve and an oil passage from the diversion control valve to the reaction mechanism. This second fixed diaphragm is a diaphragm body having a diaphragm hole. Is formed by inserting a plurality of them in series in the passage.

<Operation> The present invention divides the flow rate of the pressure oil discharged from the supply pump into the servo valve and the reaction force mechanism by the flow control valve, and divides the flow rate of the pressure oil into the reaction force mechanism. The reaction force hydraulic pressure introduced into the reaction force chamber by the first fixed throttle is controlled according to the vehicle speed. Further, the pressure oil on the servo valve side is guided to the reaction force mechanism side via the 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.

<Embodiment> An embodiment 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 rack teeth 2 of the rack shaft 22 slidable in a direction intersecting with the pinion shaft 21.
2a is meshed. 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 through the passage 37, the passage 39, and the low pressure chamber 38.

The reaction force mechanism is as follows. The rotary valve member 31 has a protrusion 50 protruding radially on both sides at the end on the pinion shaft 21 side, and the pinion shaft 21 corresponding to the protrusion 50 is formed.
A fitting groove 51 for loosely fitting the protrusion 50 around the axis of the input shaft 23 so as to be able to turn by several angles is formed therein. 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. The plunger 54 is slidably inserted in the insertion hole 53 in the radial direction,
An annular groove 55 is formed to guide the hydraulic oil to the rear portion of 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 the vehicle speed, 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. The diversion control valve 80 has a port 80a for introducing the pressure oil of the flow rate QG to the supply port 35 of the servo valve, and a port 80b for introducing the pressure oil of the flow rate QR to the introduction port 58 of the reaction mechanism. In order to control the flow rates QG and QR in accordance with the vehicle speed, the pressure oil having the constant flow rate Q is controlled to the flow rate QR according to the vehicle speed by the electromagnetic throttle valve 90 controlled according to the vehicle speed.
The spool 81 is provided with a spool 81 that guides QR to the flow dividing control valve 80 and is axially moved by the differential pressure across the electromagnetic throttle valve 90. Therefore, by changing the opening degree of the electromagnetic throttle valve 90 according to the vehicle speed, it is possible to freely change the ratio between the flow rate QR applied to the reaction mechanism and the flow rate QG supplied to the servo valve.

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

Further, a bypass passage 47 is provided between the passage communicating with the port 80a of the diversion control valve 80 and the supply port 35 of the servo valve and the passage on the reaction mechanism side, and the bypass passage 47 serves as a fixed throttle. A second fixed diaphragm 71 is provided.

As shown in FIG. 2, the second fixed throttle 71 has a structure in which a plurality of throttle bodies 73 each having a throttle hole 72 are inserted in series in a bypass passage 47 connecting the gear side G and the reaction side R.

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 to reaction force mechanism side by 80
Shunt control to QR.

The split flow rate QR to the reaction force mechanism side increases proportionally as the vehicle speed increases due to the electromagnetic throttle valve 90. This split flow rate
With the change of QR, the flow rate QG on the servo valve side is divided and controlled inversely proportionally. 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. 3, and the steering wheel operation becomes light during stationary operation and low speed.

When the vehicle speed increases, the shunt flow rate QR to the reaction force mechanism side increases due to 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 generated by the action of the first fixed throttle 70.
As a result, the plunger 54 is pressed against the engagement groove 52 with a force according to the reaction force hydraulic pressure PR, and the manual torque for relatively rotating the sleeve valve member 32 and the rotary valve member 31 increases according to the vehicle speed, 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 gear generation pressure responsive to the reaction mechanism side passage from the servo valve side passage through the second fixed throttle 71 in the bypass passage 47. A large amount of pressure g of pressure oil flows. Therefore,
The flow rate QR on the reaction mechanism side + the bypass flow rate g = the control flow rate QC are controlled 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 the control flow rate QC =
Controlled by QR + g, the characteristic of manual torque-gear generated pressure is greatly inclined as shown by the dotted line in Fig. 3 to clarify the feel of the steering feel.

<Effect of the device> As described above, according to the present invention, the constant flow rate of the pressure oil from the supply pump is shunted to the servo valve side and the reaction force mechanism side by the shunt control valve, and the flow rate diverted to the reaction force mechanism side is Since the structure is controlled by the action of a fixed throttle communicating with the low pressure side or a control throttle such as an electromagnetic throttle valve, and the gear generated pressure is introduced from the bypass passage to the reaction force mechanism side through the fixed throttle, the vehicle speed and gear generation The reaction pressure oil can be controlled according to the pressure,
Steering force characteristics proportional to the reaction pressure oil are obtained, the feeling of steering at the time of high speed traveling is increased, and the stability at high speed is improved. In particular, when the vehicle speed becomes higher, the branch flow rate divided into the reaction force mechanism increases and the reaction force pressure rises, and conversely the branch flow rate divided into the servo valve passage decreases, so that the reaction force pressure rises. And the reduction of the flow rate to the servo valve passage, the steering force at high speed can be effectively controlled.

Further, the fixed throttle on the bypass passage connecting the gear side and the reaction force side has a configuration in which a plurality of throttle bodies each having a throttle hole are inserted in series in the bypass passage. Have. Generally, a fixed throttle needs to be controlled with a very small hole diameter. Therefore, it is conceivable that the small hole diameter will be clogged with chips and dust. As a countermeasure, a filter may be arranged before and after the fixed diaphragm, but this is costly.

In the case of inserting the above-mentioned throttle body, by increasing the diameter of the throttle and providing a plurality of serial holes, the same function as a fixed throttle with one small hole diameter can be obtained, processing is easy, and clogging due to dust etc. is eliminated. It In addition, the fixed aperture amount can be set arbitrarily by increasing or decreasing the number of plural arrays.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a power steering apparatus showing an embodiment of the present invention with a hydraulic system diagram combined, FIG. 2 is a cross-sectional view of a second fixed throttle, and FIG. 3 is a curve diagram of steering characteristics. Is. 21 …… pinion shaft, 23 …… input shaft, 47 …… bypass passage, 56 …… reaction chamber, 70,70a …… first fixed throttle, 71 …… second fixed throttle, 72 …… throttle hole, 73 ...... Throttle body, 80 ...... Diversion control valve, 90 ...... Electromagnetic throttle valve.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Ikuo Okuda Ikuo Okuda 1-1, Asahi-cho, Kariya city, Aichi Toyota Koki Co., Ltd. (72) Harinori Shiratori 1-cho, Toyota city, Aichi prefecture Toyota Motor Corporation (56) References JP-A-53-87433 (JP, A) Actually opened 61-44365 (JP, U) Actually opened 50-111720 (JP, U) Actually opened 51-95825 (JP, U) Actually open 54-142835 (JP, U) Actually open 52-116837 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A servo valve for controlling the supply and discharge of pressure oil to and from a power cylinder, which is operated based on relative rotation between an input shaft and an output shaft, and a reaction force mechanism for changing a steering wheel torque according to a vehicle speed. In the steering force control device of the power steering device,
The servo valve has an electromagnetic throttle valve whose throttle area is changed according to the vehicle speed so that a constant flow rate of the pressure oil discharged from the supply pump is branched to the reaction mechanism as the vehicle speed increases. And a reaction force mechanism, a shunt control valve, a first fixed throttle for squeezing the pressure oil shunted by the reaction force mechanism to escape to the low pressure side, and an oil passage from the shunt control valve to the servo valve And a second fixed throttle provided in a passage that communicates with the oil passage from the diversion control valve to the reaction force mechanism, the second fixed throttle having a throttle body having a throttle hole in the passage. A steering force control device for a power steering device formed by inserting a plurality of devices in series.