JPH053071U - Hydraulic circuit that reduces the load on the hydraulic pump - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the load on the hydraulic pump provided in the hydraulic circuit such as the power steering device. [Structure] A hydraulic pump P, a power steering device A, and a reservoir R are provided in a closed main oil passage composed of a suction oil passage 1, a feed oil passage 2, and a return oil passage 3, and the feed oil passage 2 and the reservoir R are connected to each other. The bypass oil passage 18 is used for connection. The bypass oil passage 18 is provided with a control valve 19 which closes when the oil pressure in the feed oil passage 2 rises above a predetermined value. When the power steering device A is inoperative, the discharge oil of the hydraulic pump P directly flows back to the reservoir R via the bypass oil passage 18 to reduce the load on the hydraulic pump P.
When the power steering device A operates, the control valve 19 closes the bypass oil passage 18, and the oil discharged from the hydraulic pump P is supplied to the power steering device A.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a hydraulic circuit for reducing the load on a hydraulic pump of a power steering device of an automobile, for example.

[0002]

[Prior Art]

 Vane pumps and gear pumps are generally used as hydraulic pumps for power steering systems of automobiles, and these hydraulic pumps are connected to a crank shaft of an engine by pulleys and belts and driven. Since the power steering device requires almost no hydraulic pressure during normal traveling of the automobile, most of the oil discharged from the hydraulic pump is returned to the reservoir through the hydraulic circuit of the power steering device.

[0003]

[Problems to be solved by the device]

 In recent years, the hydraulic circuit of the power steering device has tended to be complicated as a measure against pulsation of the hydraulic pump, and the capacity of the hydraulic pump has increased with the increase in size of the vehicle. The oil that passes through the hydraulic circuit receives a large resistance to oil flow, which not only causes an increase in horsepower consumption of the hydraulic pump and deterioration of fuel consumption, but also causes vibration and noise.

The present invention has been made in view of the above circumstances, and reduces the oil passage resistance of the hydraulic circuit to reduce the load of the hydraulic pump when the actuator interposed in the hydraulic circuit is inoperative. With the goal.

[0005]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the hydraulic circuit for reducing the load of the hydraulic pump of the present invention comprises a closed main oil passage for returning the oil pumped up from the reservoir by the hydraulic pump to the reservoir and returning it to the reservoir. In a hydraulic circuit in which the oil passage resistance of the main oil passage changes between when the actuator is operating and when it is not operating, the main oil passage between the hydraulic pump and the actuator and the reservoir are connected by a bypass oil passage, and the bypass It is characterized in that a control valve is installed which closes when the actuator operates in the oil passage to increase the oil passage resistance of the main oil passage.

[0006]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show an embodiment of the present invention. FIG. 1 is a hydraulic circuit diagram of a power steering device, and FIG. 2 is a sectional view taken along line 2-2 of FIG.

As shown in FIG. 1, a hydraulic pump P, which is a balanced vane pump, is connected to a crankshaft of an engine E by a pulley and a belt and feeds oil sucked from a reservoir R via a suction oil passage 1. The oil is supplied to the power steering device A as an actuator via the oil passage 2, and the return oil from the power steering device A is returned to the reservoir R via the return oil passage 3. The suction oil passage 1, the feed oil passage 2, and the return oil passage 3 form a closed main oil passage.

The power steering device A is of a known vehicle speed sensitive type, and includes a power cylinder 4 for assisting steering force, a pair of working chambers 4 ₁ and 4 ₂ of the power cylinder 4, a hydraulic pump P and a reservoir R. A four-way valve 5 for selectively communicating with the steering wheel 6 and a valve operating mechanism 7 for switching the four-way valve 5 which is composed of a rack 7 ₁ , a pinion 7 ₂ and a pinion holder 7 _{3 which} are interlocked with the rotation of the steering wheel 6. Prepare

Further, the power steering device A has a pair of reaction plungers 8 ₂ urged by springs 8 ₁ at both ends in order to regulate the movement of the 4-way valve 5 and generate a steering reaction force according to the vehicle speed. A plurality of reaction chambers 8 that are provided, a cut-off valve 9 that controls communication / shutoff between the hydraulic pump P and the reaction chamber 8, a trochoid motor 10 ₁ that rotates at a speed proportional to the vehicle speed, a one-way valve 10 ₂ , and a relief valve. It consists 10 ₃ and a vehicle speed sensor 10 for controlling the operation of the mosquito Ttoofubarubu 9.

As shown in FIG. 2, inside the pump housing 11 of the hydraulic pump P, a cam ring 12 having an elliptical inner peripheral surface and a circular rotor 14 coupled to a rotary shaft 13 are housed. A plurality of vanes 15, which are slidably supported by slits formed in the outer periphery in the radial direction, contact the inner peripheral surface of the cam ring 12. When the rotor 14 rotates together with the rotating shaft 13, a plurality of working chambers whose volume is expanded or reduced is defined between the adjacent vanes 15, and the working chambers are sucked into the working chambers from the suction port 16 communicating with the suction oil passage 1. The oil is discharged from the discharge port 17 communicating with the feed oil passage 2.

Returning to FIG. 1, the feed oil passage 2 and the reservoir R are connected by a bypass oil passage 18 for directly returning the discharge oil of the hydraulic pump P to the reservoir R. The control valve 19 provided at the inlet end of the bypass oil passage 18 includes a small-diameter spool 20 and a large-diameter piston 21 which are integrally formed, and is biased rightward by a spring 22. When the pressure is low, the spool 20 moves to the right position shown in the figure by the biasing force of the spring 22, and the feed oil passage 2 and the bypass oil passage 18 communicate with each other via the tip of the spool 20.

Next, the operation of the embodiment of the invention having the above configuration will be described.

When the vehicle in which the steering wheel 6 is not operated is straight ahead, the 4-way valve 5 connected to the steering wheel 6 via the valve operating mechanism 7 is in the neutral position, and the operating chambers 4 ₁ , 4 of the power cylinder 4 are in the neutral position. _The hydraulic pressure is not supplied to ₂ . By operating in this state the steering wheel 6 in one direction through the valve actuating mechanism 7 4-way valve 5 is operated, the hydraulic pressure in the working chamber 4 ₁ on the left side of the power cylinder 4 via the feed oil passage 2 from the hydraulic pump P Is supplied, the steering force is assisted. The right working chamber 4 _second oil flows back to the reservoir R via the return oil passage 3. Further, when operating the steering wheel 6 in reverse, and the oil is supplied to the right side of the working chamber 4 ₂ of the power cylinder 4, the left side of the working chamber 4 ₁ oil flows back to the reservoir R.

At this time, a steering reaction force is generated by the reaction plunger 8 ₂ housed in the reaction chamber 8 moving with the operation of the 4-way valve 5, and the steering reaction force acts on the reaction chamber 8. The magnitude of hydraulic pressure increases accordingly. That is, when stopped, or the car speed of the vehicle is small because the trochoid motor 10 ₁ of the vehicle speed sensor 10 for stopping or low speed, the oil flowing into the return oil path 3 is blocked. Therefore, the cut-off valve 9 is closed and the hydraulic pressure supply to the reaction chamber 8 is cut off even if the 4-way valve 5 is slightly actuated, so that the steering reaction force becomes the smallest. This makes it possible to reduce the steering force in the case of stationary steering.

As the vehicle speed increases, the rotational speed of the trochoid motor 10 ₁ of the vehicle speed sensor 10 increases and the damming effect decreases, so that the cutoff valve 9 gradually becomes difficult to close. As a result, the hydraulic pressure acting on the reaction chamber 8 rises, and the steering reaction force becomes greater than when the vehicle is stopped or when traveling at low speed.

Even when the steering wheel 6 is not operated, the power steering device A has a certain oil passage resistance, but the oil pressure generated in the feed oil passage 2 due to the oil passage resistance is small, so The spool 20 of the control valve 19 provided in the bypass oil passage 18 branched from the oil passage 2 is held in the right position by the elastic force of the spring 22. As a result, most of the oil discharged from the hydraulic pump P is directly returned from the bypass oil passage 18 to the reservoir R and is not supplied to the power steering device A, whereby the hydraulic pump P consumes unnecessary horsepower and consumes less fuel. Is prevented from deteriorating.

On the other hand, when the power steering device A is operated by operating the steering wheel 6, the oil resistance of the power steering device A increases due to the load of the power cylinder 4, etc., and therefore acts on the right side surface of the piston 21. The difference between the hydraulic pressure and the hydraulic pressure acting on the left side surface of the spool 20 exceeds the elastic force of the spring 22, and the spool 20 moves to the left position to shut off the bypass oil passage 18. As a result, the entire amount of oil discharged from the hydraulic pump P 1 is supplied to the power steering device A 1, and the operation of the power steering device A 1 is performed without any hindrance.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various small modifications can be made without departing from the present invention described in the scope of claims for utility model registration. It is possible to make design changes.

For example, although the hydraulic circuit of the power steering device A is illustrated in the embodiment, the present invention can be applied to a hydraulic circuit including another actuator.

[0021]

[Effect of the device]

 As described above, according to the present invention, when the actuator installed in the main oil passage is inoperative, the control valve opens and the discharge oil of the hydraulic pump flows back directly to the reservoir through the bypass oil passage. The oil passage resistance of the actuator is prevented from being applied to the hydraulic pump, and as a result, the horsepower consumption of the hydraulic pump is reduced and the noise and vibration of the hydraulic pump are reduced. When the actuator operates and the oil passage resistance of the main oil passage increases, the control valve closes and the bypass oil passage closes.Therefore, the actuator supplies the entire amount of oil discharged from the hydraulic pump and operates the actuator without hindrance. Can be done.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a power steering device.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

[Explanation of symbols]

1 ... Suction oil passage (main oil passage) 2 ... Feed oil passage (main oil passage) 3 ... Return oil passage (main oil passage) 18 ... Bypass oil passage Control valve A Power steering device (actuator) P Hydraulic pump R Reservoir

Claims (1)

[Claims for utility model registration] Claims: 1. A closed main oil passage () through which oil pumped up from a reservoir (R) by a hydraulic pump (P) is returned to the reservoir (R) by passing through an actuator (A). 1, 2, 3), in the hydraulic circuit in which the oil passage resistance of the main oil passage (1, 2, 3) changes depending on whether the actuator (A) is operating or not, a hydraulic pump (P) The main oil passage (2) between the actuator (A) and the reservoir (R) are connected to the bypass oil passage (1
8), and the actuator (A) operates in the bypass oil passage (18) to operate the main oil passage (1, 2,
Control valve (19) that closes when the oil passage resistance of 3) increases
A hydraulic circuit that reduces the load on the hydraulic pump, which is characterized by being installed.