JPH0228065A - Pressure fluid pump for rear wheel steering device in vehicle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a fluid pressure pump, and more particularly, to a fluid pressure pump that discharges pressurized fluid to an actuator that steers a rear wheel of a vehicle.

(Prior art) In order to improve turning performance in recent vehicles,
A pressure fluid control device has been proposed that can control compliance steering of rear wheels using pressure fluid of a power steering device.

As a conventional pressure fluid control device for a vehicle of this type, for example, one disclosed in Japanese Patent Application Laid-Open No. 57-99470 is known.

By the way, the pressure of the fluid supplied to the power cylinder of the power steering device is generally as shown in Fig. 1.
It is preferable that the steering wheel be large when driving at low speeds in order to overcome the large road resistance, while when driving at high speeds it is preferable that the steering assist force is small in order to prevent excessive steering assist force from the partial power cylinder that reduces the road resistance. On the other hand, the pressure of the fluid supplied to the actuator that counteracts rear wheel compliance steer and prevents rear wheel toe-out is
As shown in FIG. 2, when driving at low speeds, the side force acting on the rear wheels is small, so it may be small, and when driving at high speeds, the side force is large, so it is preferably large.

For this reason, it is preferable that the fluid supplied to the power cylinder and the fluid supplied to the actuator are controlled separately.

However, as shown in FIG. 3, the fluid pressure pump 1 of a power steering device used for such a purpose is conventionally driven by a rotational output shaft 3 of an engine 2 via a belt 4 or the like. Since the rotational speed of the driving means (for example, a propeller shaft not shown) that directly changes the vehicle speed is the engine rotational speed changed by a transmission not shown, the driving rotational speed of such a fluid pressure pump 1 is There is a problem in that it cannot be made completely proportional to the vehicle speed, and the fluid pressure characteristics cannot be made ideal in relation to the vehicle speed as shown in FIGS. 1 and 2.

In addition, in the conventional pressure fluid control device described above, the flow path of the pressure fluid supplied to the power cylinder and the flow path of the pressure fluid supplied to the actuator are partially shared, so these pressure fluids are The disadvantage is that they cannot be controlled separately.

(Objective of the Invention) Therefore, the present invention aims to idealize the fluid pressure characteristics of the pressure fluid used in the actuator that controls the compliance steer of the rear wheels with respect to the vehicle speed by making the driving rotation speed of the fluid pressure pump almost completely proportional to the vehicle speed. The purpose is to control the

(Structure of the Invention) A fluid pressure pump according to the present invention includes a front wheel steering means that sucks fluid from a reservoir, transmits a steering force applied to a steering wheel to the front wheels, and biases the front wheels; a fluid pressure pump that pressurizes and discharges fluid; a pressure control valve that controls the fluid discharged by the fluid pressure pump in accordance with the steering of the steering wheel; In a vehicle rear wheel steering device comprising an actuator that biases a wheel, the fluid pressure pump is configured to be driven by vehicle drive means that drives the vehicle and has a drive rotation speed proportional to the vehicle speed. .

(Example) Embodiments of the present invention will be described below based on the drawings.

4 and 5 are diagrams showing a first embodiment of a fluid pressure pump for a rear wheel steering system of a vehicle according to the present invention.

In FIG. 4, reference numeral 11 is a vehicle body, and a front wheel 12 as a steering wheel is provided in front of the vehicle body 11 (upper part in the figure), and a rear wheel 13 is provided behind the vehicle body 11 (lower part in the figure). is provided. The front wheel 12 is connected to a rack 17 via a knuckle arm 14 and a side rod 15, and a pinion gear 18 meshes with the rack 17. The rack 17 and pinion gear 18 are housed in a gear housing 16 provided on the vehicle body 11, and a power cylinder 24 is provided at one end of the gear housing 16. A pinion shaft 19 supporting the pinion gear 18 is a first pressure control valve (power steering control valve) 2
It is connected to a column shaft 23 that supports a steering wheel 21 via a shaft 8. A first oil pump (power steering pump) 20 is connected to an inboard 28a of the first pressure control valve 28 via an oil path, and a reservoir tank 30 is connected to an out port 28b of the first oil pump 20 via an oil path. ing. Furthermore, one hole 28c of the first pressure control valve 28 is connected to the first chamber 24a of the power cylinder 24 via an oil passage, and the other hole 28d is connected to the first chamber 24a of the power cylinder 24 via an oil passage. It is connected to the second chamber 24b via an oil passage. The power piston 25 is fixed to a part of the rack 17, and the power piston 25
and rack 17 always move together. A second pressure control valve 45 is also provided at the lower end of the column shaft.

The inboard 45a of the second pressure control valve 45 is connected to the second oil pump (hydraulic pump) 22 via an oil line, and the out port 45b thereof is connected to the reservoir tank 30 via an oil line. . Further, one port 45C of the second pressure control valve 45 is connected to the first actuator cylinder 31 fixed to the vehicle body 11 via an oil passage, and the other bow 1-45d is connected via an oil passage. It is connected to a second actuator cylinder 32 which is also fixed to the vehicle body 11. These first and second actuator cylinders 3
1.32, a first actuator piston 33 and a second actuator piston 34 are fitted so as to be slidable in their axial directions. The first actuator cylinder 31 and the first actuator piston 33 collectively constitute the first actuator 35, and the second actuator cylinder 32 and the second actuator piston 34 collectively constitute the second actuator 36. do. An insulator housing 39 having an insulator rubber 38 baked and fixed therein is fixed between the first actuator piston 33 and the second actuator piston 34. 34, insulator housing 39
are integrated. A pin member 40 is fixed to the center of the insulator rubber 38 by baking, and this pin member 40 is fixed to the vehicle body 11. The insulator housing 39 is fixed to both ends of a rear wheel suspension member 42 extending in the vehicle width direction, and a differential gear housing 43 is fixed to a substantially central portion of the rear wheel suspension member 42. A rear portion of the vehicle body (lower portion in the figure) of the differential gear housing 43 is elastically supported by the vehicle body 11 via an insulator 44 . The front end of the drive shaft 48 that protrudes left and right from the differential gear housing 43 is as follows:
Each of them is connected to a rear wheel 13. A semi-trailing arm 47 is interposed between the rear wheel suspension member 42 and the rear wheel 13, and when a side force is applied to the rear wheel 13 during vehicle steering, the rear wheel suspension is suspended via the semi-trailing arm 47. - This side force is also transmitted to the John member 42, and this side force is finally absorbed by the elastic deformation of the insulator rubber 38. The deformation of the insulator rubber 38 at this time causes a relative angular displacement between the vehicle body 11 and the rear wheel suspension member 42, that is, the rear wheel 13, which appears as compliance steer of the rear wheel 13. As shown in FIG. 5, the second oil pump 22 includes a pulley 52 fixed to an output shaft 51 of a transmission 50.
It is rotationally driven via a belt 53 that is hung on. On the other hand, the first oil pump 20 is rotatably driven by the engine rotation output shaft as in the past.

Next, the effect will be explained.

When the vehicle is turning, when the driver manually rotates the steering wheel 21, the first pressure control valve 28 operates, and the first oil pump 20 supplies hydraulic oil (fluid) to the power cylinder 24 and the power piston 25. A forced movement force is applied, and a steering assist force is applied to the steering wheel 12 via the rack 17, the side rod 15, and the knuckle arm 14.
The torque applied to the steering wheel 21 by the occupant is doubled. As a result, the steering force that would otherwise be generated by the occupant rotating the steering wheel 21 in the absence of the power cylinder 24 can be reduced.

Simultaneously with this action, the second oil pump 22 supplies hydraulic oil (fluid) to the first actuator cylinder 31 or the second actuator cylinder 32 by the operation of the second pressure control valve 45, and the insulator housing 3
9 is forcibly moved and displaced. This displacement of the insulator housing 39 can offset the eccentric elastic deformation of the insulator rubber 38 caused by the compliance steer of the rear wheel, and as a result, the deterioration of turning performance due to the compliance steer of the rear wheel 13 is prevented and the turning Performance can be improved. At this time, the first
The oil pump 20 is of a well-known type that is responsive to engine speed; when the engine speed is high, the flow rate of hydraulic oil supplied decreases, and when the engine speed is low, the flow rate of hydraulic oil supplied increases.

Therefore, when driving at low speeds, the steering wheel 12 can be easily steered by overcoming large road resistance, and at the same time, it is possible to prevent deterioration of vehicle directionality due to excessive turning of the steering wheels 12 when driving at high speeds. I can do it. The first oil pump 20 may be of a vehicle speed sensitive type, which is known as a vehicle speed sensitive type, in which the flow rate of hydraulic oil supplied decreases when the vehicle speed is high, and increases when the vehicle speed is low. . On the other hand, the second oil pump 22 is configured to increase the supply flow rate of hydraulic oil when the vehicle speed is high, and to decrease the supply flow rate when the vehicle speed is low. Therefore, when driving at low speeds, it is possible to suppress the compliance steer of the rear wheels 13 that occurs in response to small side forces acting on the rear wheels 13, and when driving at high speeds, it is possible to suppress the compliance steer that occurs in response to small side forces acting on the rear wheels 13 (large side forces). Large compliance steer that occurs in the rear wheels 13 in response to force can be prevented.

By the way, as mentioned above, the second oil pump 22 is
Output shaft 5 of transmission 50 via J52 and belt 53
1 (vehicle drive means). Since the rotational speed of the output shaft 51 of the transmission 50 is the engine rotational speed changed by the transmission 50, the driving rotational speed of the second oil pump 22, that is, the supply flow rate of hydraulic oil is approximately proportional to the vehicle speed. It has become. Therefore, the second
As shown in the figure, the fluid pressure characteristics of the rear wheel actuator relative to the vehicle speed can be ideally controlled.

FIG. 6 shows a second embodiment. In the first embodiment, the rotation of the output shaft 51 of the transmission 50 was transmitted via the boot IJ 52 and the belt 53, whereas in the second embodiment, the rotation of the output shaft 51 was transmitted via the gears 55 and 56. It transmits rotation. Unlike the belt 53, no slip occurs, so rotation proportional to the vehicle speed can be more reliably extracted.

FIG. 7 shows a third embodiment. In the first embodiment, rotation is extracted from the output shaft 51 of the transmission 50, whereas in this third embodiment, rotation is extracted from the rear end of the propeller shaft 57.

9 is applied when the second oil pump 22 cannot be provided near the output shaft 51.

FIG. 8 shows a fourth embodiment. While in the first embodiment, the rotation was extracted from the output shaft 51 of the transmission 50, in this fourth embodiment, the rotation was extracted from the output shaft 51 of the transmission 50.
Rotation is extracted from the left and right rotation extraction shaft 59. A second shaft is installed near the output shaft 51 and propeller shaft 57
This can be applied when the oil pump 22 cannot be provided.

FIG. 9 shows a fifth embodiment. While the first to fourth embodiments are applied to rear-wheel drive vehicles,
This fifth embodiment can be applied to a front wheel drive vehicle. That is, the front wheel differential gear 6
Rotation is extracted from a drive shaft 61 extending from the left and right sides of 0 via a belt 62 and the like.

(Effects of the Invention) As described above, according to the present invention, the driving rotation speed of the fluid pressure pump is made almost completely proportional to the vehicle speed, and the pressure fluid used in the rear wheel steering system of the vehicle is adjusted to the vehicle speed. Pressure characteristics can be ideally controlled.

Further, in the second to fourth embodiments, a wide variety of layouts can be provided, and in the fifth embodiment, it is also possible to apply the present invention to front-wheel drive vehicles.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the most preferable relationship between vehicle speed and pump flow rate in a power steering device, Fig. 2 is a graph showing the most preferable relationship between vehicle speed and pump flow rate in an actuator that prevents rear wheel compliance steer, and Fig. FIG. 4 is a perspective view showing a conventional oil pump drive system, and FIG. 4 is a schematic plan view of a vehicle equipped with a power steering device and a rear wheel compliance steer prevention device that apply a fluid pressure pump according to the first embodiment of the present invention. , 5th
FIG. 6 is a perspective view showing a fluid pressure pump according to a second embodiment of the invention, and FIG. 7 is a perspective view showing a fluid pressure pump according to a second embodiment of the invention. FIG. 8 is a perspective view of a fluid pressure pump according to a fourth embodiment of the present invention, and FIG. 9 is a plan view showing a fluid pressure pump according to a fifth embodiment of the present invention. It is. 11...Vehicle body, 12...Front wheel, 13...Rear wheel, 14...Knuckle arm, 15...Side rond, 17. ... Rack, 18 ... Pinion gear, 20 ... First oil pump (power steering pump), 21 ... Steering wheel, 22 ...
...Second oil pump (fluid pressure pump), 23...
... Column shaft, 24 ... Power cylinder, 25 ... Power piston, 28 ... First pressure control valve (power steering control valve), 30 ...・Reservoir tank, 35...First actuator, 36...
・Second actuator, 38... Insulator rubber 39... Insulator housing,
40... Bin member, 42... Rear wheel suspension member, 43...
...Differential gear housing, 45...
...Second pressure control valve (pressure control valve), 47...
... Semi-trailing arm, 48 ... Drive shaft, 51 ... Output shaft, 57 ... Propeller shaft, 58 ... Differential gear, 59 ...・
...Left and right rotation extraction shaft, 60...Differential gear for front wheels, 61...Drive shaft. Figure 1 Figure 3 Figure 2 Figure 5 Figure Figure Figure

Claims (2)

[Claims] (1) Front wheel steering means that transmits the steering force applied to the steering wheel to the front wheels and deflects the front wheels, a fluid pressure pump that sucks fluid from a reservoir, pressurizes the fluid, and discharges it, and the fluid pressure pump discharges the fluid. A rear wheel steering system for a vehicle comprising: a pressure control valve that controls the fluid in response to the steering of the steering wheel; and an actuator that is supplied with the fluid controlled by the pressure control valve and biases the rear wheels. A fluid pressure pump for a rear wheel steering system of a vehicle, characterized in that the pressure pump is driven by vehicle drive means that drives the vehicle and has a drive rotation speed proportional to the vehicle speed. (2) The front wheel steering means includes a power steering pump that sucks fluid from a reservoir, pressurizes the fluid, and discharges it; and a power steering control valve that controls the fluid discharged by the power steering pump in accordance with the steering of the steering wheel. and a power cylinder that biases the front wheels by being supplied with fluid controlled by a power steering control valve, the power steering pump having a discharge flow rate that decreases when the vehicle speed or engine rotation speed is high. 2. The fluid pressure pump for a rear wheel steering system of a vehicle according to claim 1, wherein the discharge flow rate of the fluid pressure pump increases when the vehicle speed or the engine speed is high.