JPH07165091A - Pump for vehicle power steering system - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the efficiency of the engine from decreasing by rotating the pump at a low speed when the engine speed is high. A pump shaft 17 is connected to a crankshaft of an engine 21 via a belt or the like to supply pressure oil to a vehicle power steering device, and a pump shaft is internally provided in the pump 14 of the vehicle power steering device. Shaft housings 43 and 44 rotatably arranged with respect to the lever pump shaft and connected to the belt and the like, an electrorheological fluid 45 filled between the shaft housing and the pump shaft, a shaft housing and a pump shaft And a voltage control device 49 for applying a voltage according to the engine speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle power steering system pump, and more particularly to a vehicle power steering system pump for controlling the amount of pressure oil discharged from the pump in accordance with the engine speed.

[0002]

2. Description of the Related Art Generally, a vehicle power steering system, when a steering wheel is rotationally steered, generates a steering assist force in accordance with the steering force and turns the front wheels by the steering force and the steering assist force. The vehicle can be steered lightly.

In such a power steering device,
There is a demand for increasing the steering assist force at low speeds of the vehicle, particularly during stationary steering operation, and decreasing the steering assist force at high speeds. However, since the pump that pumps pressure oil to the power steering device is driven by the engine, a large amount of pressure oil is supplied to the power steering device when the engine rotates at high speed.

Therefore, in the conventional power steering apparatus, a flow control valve is installed on the discharge port side of the pump,
Most of the pressure oil discharged from the pump at high engine speed is returned to the tank, and a small amount of pressure oil is supplied to the power steering device to improve the steering stability at high vehicle speeds.

[0005]

However, as described above, even if most of the pressure oil discharged from the pump at the time of high engine rotation is returned to the tank by the flow control valve, the pump itself is rotated at high speed by the engine. Therefore, an unnecessary load acts on the engine, resulting in a large engine loss and a reduction in engine efficiency.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pump for a power steering system for a vehicle, which can rotate the pump at a low speed when the engine is rotating at a high speed to prevent a decrease in the efficiency of the engine. And

[0007]

SUMMARY OF THE INVENTION The present invention relates to a pump for a vehicle power steering apparatus, in which a pump shaft is connected to a crankshaft of an engine via a power transmission mechanism to pump pressure oil to the vehicle power steering apparatus. A shaft housing internally provided with the pump shaft and rotatably disposed with respect to the pump shaft, and connected to the power transmission mechanism; and an electrorheological fluid filled between the shaft housing and the pump shaft. A voltage control device that applies a voltage between the shaft housing and the pump shaft according to the rotation speed of the engine.

[0008]

Therefore, according to the pump of the power steering system for a vehicle according to the present invention, the voltage control device applies a high voltage between the pump shaft and the shaft housing to increase the viscosity of the electrorheological fluid when the engine speed is low. , To reduce slippage between the shaft housing rotationally driven by the engine and the pump shaft. Then, the pump shaft rotates at substantially the same speed as the engine crankshaft, and a large amount of pressure oil can be supplied to the vehicle power steering.

Further, when the engine is running at high speed, the voltage control device applies a minute voltage between the pump shaft and the shaft housing to reduce the viscosity of the electrorheological fluid, thereby increasing the slip between the shaft housing and the pump shaft. To do. Then, the pump shaft rotates at a speed lower than the engine speed, and a small amount of pressure oil is pumped to the vehicle steering device.

As described above, the voltage control device controls the voltage applied to the electrorheological fluid to control the viscous resistance of the electrorheological fluid so that the pump shaft rotates at a low speed when the engine rotates at a high speed. It is possible to reduce the energy loss of the engine, and to prevent the efficiency of the engine from being reduced, especially the output reduction at the time of high engine rotation.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of a pump of a vehicle power steering device according to the present invention. FIG. 2 is a perspective view showing a vehicle power steering device to which the pump of FIG. 1 is applied.

The power steering device 10 shown in FIG.
Is a rack and pinion type power steering device. In this power steering device 10, the steering force acting on the steering wheel 11 is transmitted to a rack (not shown) in the power cylinder 12 via a pinion (not shown). On the other hand, the steering wheel 1
The steering force of No. 1 is transmitted to the servo valve device 13, and the servo valve device 13 switches the flow of the pressure oil discharged from the pump 14 and also causes the pressure oil to generate a hydraulic pressure corresponding to the steering force. The pressure oil presses a piston (not shown) fixed to the rack of the power cylinder 12 to generate a steering assist force. The steering force and the steering assist force turn the front wheels 16 via the knuckle arm 15.

A pump shaft pulley 18 is provided on a pump shaft 17 of a pump 14 for sending pressure oil to the power steering device 11. This pump shaft pulley 18 is connected to the crank pulley 2 via a belt 19.
It is connected to 0. The crank pulley 20 has an engine 21.
Is a pulley fixed to the crankshaft 22 of the engine, and the pump shaft 17 is rotationally driven by the engine 21 by the crank pulley 20, the belt 19 and the pump shaft pulley 18 which are these power transmission mechanisms.

The pump 14 is a vane pump as shown in FIG. That is, the pump shaft 17 is rotatably arranged in the pump housing 23 via the bearing 24, and the rotor 25 is spline-coupled to one end of the pump shaft 17 in a rotationally integrated manner. A cam ring 26 is mounted on the outer peripheral side of the rotor 25 in the pump housing 23, and a side plate 27 is attached to one side surface of the rotor 25.
Are installed in a biased state by the spring 28. Further, a housing cap 29 is fixed to the pump housing 23 on the other side surface side of the rotor 25 using bolts 30, and a space 31 surrounded by the outer peripheral surface of the rotor 25 and the inner peripheral surface of the cam ring 26 is formed.

The space 31 is provided in the pump housing 23.
A suction passage 32 and a discharge passage 33 for the pressure oil are formed in communication with the suction passage 32, a suction port 34 is formed at the open end of the suction passage 32, and a discharge port 35 is formed at the open end of the discharge passage 33. A low pressure hose 36 (FIG. 1) is connected to the suction port 34, and a high pressure hose 37 (FIG. 1) is connected to the discharge port 35.

The rotor 25 has a plurality of vanes 38.
Are radially slidably stored. When the rotor 25 rotates, the vanes 38 slide outward in the radial direction of the rotor 25,
The tip of the vane 38 contacts the inner peripheral surface of the cam ring 26,
The space 31 is divided into a plurality of pressure chambers 39 by these vanes 38. The pressure oil is filled in each of the pressure chambers 39.

When the rotor 25 rotates due to the rotation of the crankshaft 22, the volume of the pressure chamber 39 increases or decreases to perform a pumping action, so that the pressure oil introduced from the suction port 34 to the pressure chamber 39 through the suction passage 32 is Discharge from the discharge port 35 through the discharge passage 33. Reference numeral 40 in FIG. 1 is an oil seal.

Now, the other end 17A of the pump shaft 17
The shaft main housing 43 through the bearing 41,
In addition, the shaft sub-housing 44 via the bearing 42
Are rotatably arranged. The shaft surface housing 43 and the shaft sub-housing 44 are fixed to each other, and the other end 17A of the pump shaft 17 is housed inside. These shaft main housing 43, shaft sub-housing 44, and pump shaft 1
In the space surrounded by the other end 17A of the electromagnetic viscous fluid 45
(Described later) is filled. A belt groove 46 into which the belt 19 is fitted is provided on the outer circumference of the shaft main housing 43.
The shaft main housing 43 and the shaft sub-housing 44 function as the pump shaft pulley 18.

Inside the shaft main housing 43 and the shaft sub-housing 44, a plurality of inner plates 47 and outer plates 48 are alternately arranged in a laminated state. The inner plate 47 is spline-coupled to the other end 17A of the pump shaft 17 in a rotationally integrated manner. The outer plate 48 is spline-coupled to the shaft main housing 43 in a rotationally integrated manner. Therefore, the outer plate 48 rotates integrally with the shaft main housing 43 and the shaft sub housing 44, and the inner plate 47 rotates integrally with the pump shaft 17.

On the other hand, the shaft main housing 43, the shaft sub housing 44, and the outer plate 48.
Functions as a positive electrode and is connected to the voltage controller 49. The other end 17A of the pump shaft 17 and the inner plate 47 function as a negative electrode and are grounded. Between the shaft main housing 43 and the bearing 41, and further between the shaft sub housing 44 and the bearing 4.
An insulating plate 50 is interposed between the two. The pump shaft 17 has an insulating plate 5 between the other end 17A and the remaining portion.
0 is inserted. A voltage is applied from the voltage control device 49 to the electromagnetic viscous fluid 45 via the shaft main housing 43, the shaft sub-housing 44, the outer plate 48, the inner plate 44 and the other end 17A of the pump shaft 17.

The electromagnetic viscous fluid 45 is mainly composed of a continuous layer of silicone oil or the like and a dispersion layer of starch, gelatin, gypsum or the like. When a voltage is applied, its viscous resistance is changed. It is a fluid that increases based on the Winslow effect. The viscous resistance with respect to the increase of the applied voltage has a substantially proportional relationship.

The voltage control device 49 is connected to an engine speed detection sensor 51 installed in the engine 21 and applies a high voltage to the electrorheological fluid 45 at the time of low engine rotation or idling rotation, and at the time of high engine rotation or medium speed. It is configured to apply a minute voltage (low voltage or 0 voltage) to the electrorheological fluid 45 during rotation.

Therefore, when the engine is rotating at low speed or idling, the electrorheological fluid 45 is fed from the voltage controller 49.
When a high voltage is applied to the electrorheological fluid 45, the viscous resistance of the electrorheological fluid 45 increases due to the Winslow effect, and the slip between the inner plate 47 and the outer plate 48 becomes smaller. Then, the pump shaft 17 rotates at substantially the same speed as the shaft main housing 43 and the shaft sub-housing 44, and a large amount of pressure oil is pumped from the pump 14 to the power steering device 10 via the servo valve device 13. At 10, a large steering assist force is generated.

When a minute voltage is applied to the electrorheological fluid 45 at the time of high engine rotation or middle engine rotation, the electrorheological fluid 45 has a reduced viscous resistance due to the Winslow effect, and the inner plate 47 and the outer plate 48.
The slip between them becomes large. Then, the pump shaft 17
Rotates at a low speed with respect to the shaft main housing 43 and the shaft sub-housing 44, and the power steering device 1 from the pump 14 via the servo valve device 13.
A small amount of pressure oil is supplied to 0, the steering assist force generated by the power steering device 10 is reduced, and the high-speed stability performance of the vehicle is improved.

According to the above embodiment, the shaft main housing 43 and the shaft sub-housing 44 as the pump shaft pulley 18 are attached to the engine 21 by the belt 19.
And the electro-rheological fluid 45 is filled between the shaft main housing 43 and the shaft sub-housing 44 and the pump shaft 17 of the pump 14, and the voltage control device 49 controls the voltage applied to the electro-rheological fluid 45. Then, the viscous resistance of the electrorheological fluid 45 is controlled so that the pump shaft 17 is rotated at a low speed when the engine 21 is rotating at a high speed or a medium speed. Therefore, it is not necessary to rotate the pump shaft 17 unnecessarily. The energy loss of 21 can be reduced and the efficiency of the engine can be prevented from lowering.

Further, since the pump 14 can reduce the discharge amount of the pressure oil at the time of high engine rotation or medium rotation, the flow control valve installed at the discharge port 32 can be eliminated or simplified, and as a result, the pump 14 Pump housing 2
3 can be miniaturized.

Further, the shaft main housing 43 and the shaft sub-housing 44 capable of being filled with the electrorheological fluid 45 function as the pump shaft pulley 18, and the pump shaft pulley 18 has substantially the same size as a conventional pump shaft pulley. Therefore, the pump 14 does not increase in size.

The voltage control device 49 may be configured so that the applied voltage can be changed according to the preference of the driver who gets in the vehicle. For example, in the case of a female driver, if the voltage control device 49 is operated to set a larger voltage to be applied to the electrorheological fluid 45, the viscous resistance of the electrorheological fluid 45 increases, and the rotation speed of the pump shaft 17 increases. Increased,
The amount of pressure oil discharged from the pump 14 increases, and the steering assist force of the power steering device 10 can be increased.
In other words, the steering feeling can be changed depending on the difference between male and female drivers.

[0029]

As described above, according to the pump of the vehicle power steering device of the present invention, the efficiency of the engine can be prevented from being lowered by rotating the pump at a low speed when the engine is rotating at a high speed.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a pump of a vehicle power steering device according to the present invention.

FIG. 2 is a perspective view showing a vehicle power steering apparatus to which the pump of FIG. 1 is applied.

[Explanation of symbols]

 10 Power Steering Device 14 Pump 16 Front Wheel 17 Pump Shaft 18 Pump Shaft Pulley 21 Engine 22 Crank Shaft 43 Shaft Main Housing 44 Shaft Sub Housing 45 Electrorheological Fluid 47 Inner Plate 48 Outer Plate 49 Voltage Control Device 51 Engine Speed Detection Sensor

Claims (2)

[Claims] 1. A pump for a vehicle power steering device, wherein a pump shaft is connected to a crankshaft of an engine via a power transmission mechanism to pump pressure oil to the vehicle power steering device, wherein the pump shaft is internally provided. A shaft housing rotatably disposed with respect to the lever pump shaft and connected to the power transmission mechanism; and an electrorheological fluid filled between the shaft housing and the pump shaft,
A voltage control device for applying a voltage between the shaft housing and the pump shaft according to the number of revolutions of the engine, the pump of a power steering device for a vehicle. 2. The pump for a vehicle power steering device according to claim 1, wherein the voltage control device is configured to apply a minute voltage when the engine is rotating at a high speed.