JP2003013905A - Hydraulic pressure supplying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic pressure supplying device which reduces excess load on the device even if an inexpensive fixed capacity pump is used and preventing the occurrence of cavitation as well. SOLUTION: An accumulator 10 is connected to a fixed capacity hydraulic pressure pump 9 driven by an engine 13 through a duct 16 passing through a restrictor 17 and a check valve 18 installed therein. The duct 16 is connected to a return duct 19 through a 1st and 2nd unload control valves 11, 12. When the accumulated pressure of the accumulator 10 reaches a described pressure, the 1st unload control valve 11 is opened, making the use of said accumulated pressure as a pilot pressure, to unload the hydraulic pump 9, thereby keeps the accumulated pressure of the accumulator 10 fairly constant. In the high speed range of engine 13, the discharge of the hydraulic pressure pump 9 increases, this in turn causes an increase in the differential pressure between the upstream and downstream sides. The increased differential pressure is utilized as a pilot pressure to open the 2nd unload control valve 12 so as to unload the hydraulic pressure pump 9, hence preventing the increase in an excess load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic pressure supply device for supplying hydraulic pressure to a cylinder device of a hydraulic active suspension of an automobile or the like.

[0002]

2. Description of the Related Art A conventional hydraulic pressure supply device for supplying hydraulic pressure to a hydraulic device such as a hydraulic cylinder of a hydraulic active suspension of an automobile will be described with reference to FIG. Figure 4
As shown in, the hydraulic pressure supply device 1 is roughly configured by a hydraulic pump 2, an accumulator 3, a check valve 4 provided between them, and an unload control valve 5.

Then, the hydraulic pump 2 is directly driven by the engine 6 to suck the oil liquid from the oil tank 7, and the discharge pressure of the hydraulic pump 2 is stored in the accumulator 3 via the check valve 4.
The pressure is accumulated in and is supplied to the hydraulic device. Unload control valve 5
Introduces the accumulated pressure of the accumulator 3 as a pilot pressure, and when this accumulated pressure reaches a predetermined pressure, the hydraulic pump 2 is unloaded by connecting the discharge side of the hydraulic pump 2 to the tank 7 side. As a result, the pressure accumulated in the accumulator 3 can be maintained substantially constant, the surplus load on the hydraulic pump 2 can be reduced, and the load on the engine 6 can be reduced.

[0004]

However, the above-described conventional hydraulic pressure supply device 1 has the following problems. When an inexpensive fixed displacement pump (for example, fixed displacement gear pump) is used as the hydraulic pump 2 for cost reduction and the like, the discharge amount of the hydraulic pump 2 largely changes depending on the rotation speed of the engine 6. Therefore, when the engine 6 is rotating at a high speed, the discharge amount of the hydraulic pump 2 excessively increases, and the surplus load increases, which deteriorates the fuel consumption rate of the engine 6. Further, due to insufficient suction of the hydraulic pump 2 at the time of high rotation of the engine 6, cavitation occurs, which causes vibration, noise, and shortens the life of the hydraulic pump 2.

A variable displacement pump is used as the hydraulic pump 2, and the hydraulic pump 2 is changed in accordance with the rotation speed of the engine 6.
However, in this case, an expensive variable displacement pump is required, which causes a problem that the manufacturing cost of the hydraulic pressure supply device increases.

The present invention has been made in view of the above points, and provides an oil pressure supply device capable of reducing excess load and preventing cavitation by using an inexpensive fixed displacement pump. The purpose is to

[0007]

In order to solve the above-mentioned problems, the hydraulic pressure supply device according to the invention of claim 1 is connected to a hydraulic pump and a throttle means and a check valve to the hydraulic pump. An accumulator and unloading means for unloading the hydraulic pump are provided, and the unloading means uses the accumulated pressure of the accumulator as a pilot pressure, and when the accumulated pressure reaches a predetermined pressure, the hydraulic pump is A first unload control valve for unloading, and a second unload for unloading the hydraulic pump when the differential pressure reaches a predetermined differential pressure, using the differential pressure between the upstream side and the downstream side of the throttle means as a pilot pressure. It is characterized by comprising a load control valve. With this configuration, when the accumulated pressure in the accumulator reaches the predetermined pressure, the first unload control valve unloads the hydraulic pump to maintain the accumulated pressure in the accumulator substantially constant. Further, when the flow rate of the throttle means increases due to an increase in the discharge amount of the hydraulic pump, the pressure loss of the throttle means increases the differential pressure between the upstream side and the downstream side, and when the differential pressure reaches a predetermined differential pressure, The second unload control valve unloads the hydraulic pump to prevent an increase in excess load. According to a second aspect of the invention, in the configuration of the first aspect, the hydraulic pressure supply device has the first
The unloading control valve and the second unloading control valve are integrated. With this configuration, it is possible to share the hydraulic circuit and parts between the first unload control valve and the second unload control valve.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. A first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the hydraulic pressure supply device 8 of the present embodiment is for supplying hydraulic pressure to a hydraulic device such as a hydraulic cylinder of an active suspension of an automobile, and includes a hydraulic pump 9 and an accumulator 10.
And a first unload control valve 11 (unload means) and a second unload control valve 12 (unload means).

The hydraulic pump 9 is a fixed displacement pump such as a gear pump and is directly driven by the engine 13 of the automobile. The suction side of the hydraulic pump 9 is connected to the oil tank 15 by the pipe line 14, and the discharge side is connected to the accumulator 10 by the pipe line 16. The pipe line 16 is provided with a throttle 17 on its upstream side, and a check valve which allows only the flow of oil liquid from the hydraulic pump 9 side to the accumulator 10 side on the downstream side.
18 are provided. The accumulator 10 is connected to the hydraulic system and the return line 19 from the hydraulic system is connected to the oil tank 15.
It is connected to the.

The first unload control valve 11 is a pilot-type on-off valve, in which the high pressure port 20 is connected to the upstream side of the check valve 18 of the pipe line 16, and the low pressure port 21 is connected to the return pipe line 19. And the pilot line 22 is connected to the accumulator 10. And, normally, the spool 23 is replaced by the spring 24.
By being urged to the valve closing position shown by the drawing, the high pressure and low pressure ports 20 and 21 are shut off, and when the accumulated pressure (pilot pressure) of the accumulator 10 introduced from the pilot conduit 22 reaches a predetermined pressure, The pressure causes the spool 24 to spring
The high pressure and low pressure ports 20 and 21 are communicated by moving to the valve opening position against the biasing force of 23.

The second unload control valve 12 is a pilot type on-off valve, and the high pressure port 25 is a check valve with the throttle 17 of the pipeline 16.
18 and the low pressure port 26 is connected to the return line 19, and two pilot lines 27 and 28 are connected to the line.
The 16 throttles 17 are connected to the upstream side and the downstream side, respectively. Then, normally, the spool 29 is in the valve closing position shown by the pressure receiving area difference between both ends thereof and the urging force of the spring 30, and shuts off the high pressure and low pressure ports 25, 26, and by the pilot conduits 27, 28. When the differential pressure (pilot pressure) between the upstream side and the downstream side of the throttle 17 introduced reaches a predetermined pressure, the spool 29 moves to the valve opening position against the biasing force of the spring 30, and the high pressure and low pressure ports. Connect between 25 and 26.

The passage area of the throttle 17 is such that pressure can be smoothly accumulated in the accumulator 10 in the low rotation region of the engine 13 and the hydraulic pump 9 can be stored in the high rotation region of the engine 13.
So that unloading can be performed, for example, the discharge rate of the hydraulic pump 9 is 50 l / min or more (engine speed is 6000 rpm or more)
At the same time, it is set so that a predetermined differential pressure is generated between the upstream side and the downstream side of the throttle 17, and the spool 29 is set by this differential pressure.
The pressure receiving area difference between both ends of the spool 29 and the biasing force of the spring 30 are set so that the spring can move.

The operation of this embodiment having the above-described structure will be described below. By the rotation of the engine 13, the hydraulic pump 9 is directly driven to suck up the oil liquid from the oil tank 15, discharge it to the pipe line 16, and supply it to the accumulator 10 via the throttle 17 and the check valve 18 to accumulate pressure. . Accumulator 10
When the accumulated pressure rises and reaches a predetermined pressure, the spool 23 of the first unload control valve 11 moves using this pressure as a pilot pressure, and the high pressure and low pressure ports 20 and 21 communicate with each other. As a result, the discharge side pipe 16 of the hydraulic pump 16 and the return pipe 19 are communicated with each other, and the hydraulic pump 9 is unloaded. When the accumulated pressure in the accumulator 10 is consumed by the hydraulic device and drops, the pilot pressure drops, the first unload control valve 11 closes, and the high pressure and low pressure ports 20 and 21 are shut off. As a result, the unloading of the hydraulic pump 9 is released, and the pressure accumulation in the accumulator 10 is started.
In this way, the accumulated pressure of the accumulator 10 can be maintained substantially constant.

The rotation speed of the engine 13 is increased, and the hydraulic pump
When the discharge amount of 9 increases, the pressure loss due to the throttle 17 of the pipeline 16 increases, and the differential pressure between the upstream side and the downstream side of the throttle 17 increases. As a result, the differential pressure introduced from the pilot conduits 27, 28 increases, and when the predetermined differential pressure is reached, the spool 29 of the second unload control valve 12 is moved to the valve opening position by this differential pressure, The high pressure and low pressure ports 25 and 26 are connected.
Then, the discharge side pipe 16 of the hydraulic pump 19 and the return pipe 19 are communicated with each other, and the hydraulic pump 9 is unloaded. Thus, in the high rotation range of the engine 13, the hydraulic pump
The engine 9 can be unloaded, the surplus load can be prevented from increasing, and the fuel consumption rate of the engine 13 can be improved. Further, it is possible to prevent the occurrence of cavitation due to insufficient suction of the hydraulic pump 9, and it is possible to prevent vibration and noise due to cavitation and prevent the life of the hydraulic pump 9 from being shortened. As a result, an inexpensive fixed displacement pump can be used, and the manufacturing cost of the hydraulic pressure supply device can be reduced.

Next, an example of the operation of the hydraulic pressure supply device 8 will be described with reference to the time chart shown in FIG. Figure 3
At time T ₁ , the engine 13 is started and the pressure oil discharged by the hydraulic pump 9 is accumulated in the accumulator 10. At time T ₂ , the accumulated pressure of the accumulator 10 reaches a predetermined pressure, the first unload control valve 11 starts opening, and the hydraulic pump 9 is unloaded. At time T ₃ , the first unload control valve 11 is fully opened, and thereafter, when the accumulated pressure of the accumulator 10 is consumed and drops, the first unload control valve 11
Is closed and fully closed at time T ₄ . As a result, the pressure of the accumulator 10 rises, the first unload control valve 11 opens, the hydraulic pump 9 is unloaded, and the first unload control valve 11 is fully opened at time T ₅ . In this manner, the first unload control valve 11 opens and closes according to the accumulated pressure of the accumulator 10 to unload and on-load the hydraulic pump 9, thereby maintaining the accumulated pressure of the accumulator 10 substantially constant. .

At time T ₆ , the discharge amount of the hydraulic pump 9 increases due to the increase in the rotation speed of the engine 13, and the throttle 17
The differential pressure between the upstream side and the downstream side increases, the second unload control valve 12 opens, and the hydraulic pump 9 is unloaded.
Thereafter, at time T _7, the rotational speed of the engine is reduced, but the discharge amount of the hydraulic pump 9 is released unloaded by the second unload control valve 11 decreases, until the time T _8, the accumulator 10 The pressure causes the first unload control valve 11 to open and the hydraulic pump 9 to be unloaded. After that, the pressure of the accumulator 10 drops, and the first unload control valve 11
Closes and becomes fully closed at time T ₉ . In this way, when the engine 13 is rotating at high speed, the second unload control valve 12 is opened to unload the hydraulic pump 9, thereby preventing an increase in surplus load.

Next, a second embodiment of the present invention will be described with reference to FIG.
Will be described with reference to. The second embodiment is the same as that shown in FIG. 1, since the first unload control valve and the second unload control valve are integrated with respect to the first embodiment. The same reference numerals are given to the parts, and only different parts will be described in detail.

As shown in FIG. 2, in the hydraulic pressure supply device 31 of the present embodiment, one unload control valve 32 in which the first and second unload control valves 11 and 12 of the first embodiment are integrated is provided. It is provided.

The unload control valve 32 is a pilot type on-off valve consisting of a spool valve 33 and a pilot operating portion 34. In the spool valve 33, the high pressure port 35 is connected between the throttle 17 of the pipeline 16 and the check valve 18, and the low pressure port 36 is connected to the return pipeline 19.
Normally, the spool 37 is urged to the valve closing position shown in FIG. 2 by the spring 38 abutting on one end of the spool 37, and the high pressure and low pressure ports 35 and 36 are shut off. Is moved to the valve opening position against the biasing force of the spring 38, the high pressure and low pressure ports 35 and 36 are communicated with each other.

In the pilot operating portion 34, a piston 40 having rods 40A, 40B at both ends is slidably fitted in a cylinder bore 39, and two pilot chambers 39A, 39B are formed in the cylinder bore 39. . One rod 40A of the piston 40 extends into the spool bore of the spool valve 33,
Its tip is in contact with the other end of the spool 37. The other rod 40B of the piston 40 is slidably inserted into the small diameter bore 41, and a pilot chamber 41A is formed in the small diameter bore 41. Pilot room 39A has 28
Is connected to the downstream side of the throttle 17 of the pipeline 16 by means of the pilot chamber 39B by the pilot pipeline 27.
Is connected to the upstream side, and the pilot chamber 41A is connected to the accumulator 10 by the pilot pipe line 22.

The operation of the present embodiment configured as described above will be described below. When the accumulated pressure of the accumulator 10 reaches a predetermined pressure by the discharge of the hydraulic pump 9, the piston 40 moves to the spool valve 33 side by the accumulated pressure (pilot pressure) of the accumulator 10 introduced into the pilot chamber 41A by the pilot line 22. Then, the rod 40A moves the spool 37 to the valve opening position against the biasing force of the spring 38, the high pressure and low pressure ports 35 and 36 are communicated with each other, and the hydraulic pump 9 is unloaded. As a result, similarly to the first embodiment, the accumulated pressure of the accumulator 10 can be maintained substantially constant.

The rotation speed of the engine 13 is increased and the hydraulic pump
When the discharge amount of 9 increases, the pressure loss due to the throttle 17 of the pipeline 16 increases, and the differential pressure between the upstream side and the downstream side of the throttle 17 increases. As a result, the differential pressure of the pilot pressure introduced from the pilot pipe lines 27, 28 into the pilot chambers 39B, 39A increases. When this differential pressure reaches a predetermined differential pressure, the piston 40 moves to the spool valve 33 side and the rod 40A causes the spool 37 to move to the spring 3 side.
The valve is moved to the valve open position against the biasing force of 8, the high pressure and low pressure ports 35 and 36 are communicated with each other, and the hydraulic pump 9 is unloaded. In this way, similarly to the first embodiment, the hydraulic pump 9 can be unloaded in the high rotation range of the engine 13, and an increase in surplus load can be prevented.

By integrating the first and second unload control valves into the unload control valve 32, these pipelines and parts can be shared, so that the number of parts can be reduced and the circuit can be reduced. The simplification can be achieved, and the manufacturing cost can be reduced.

In the second embodiment, the spool 37
And piston 40 abut each other to integrate them, and spool
Although the one in which the 37 and the piston 40 are slid together is shown, the spool 37 and the piston 40 are not limited to this.
And may be integrally molded in advance.

In the first and second embodiments, the pilot type on-off valve using the spool valve as the unload control valve is used as an example, but the present invention is not limited to this. Alternatively, a pilot-type on-off valve using another type of valve means such as a poppet valve may be used.

[0026]

As described above in detail, according to the hydraulic pressure supply device of the invention of claim 1, when the accumulated pressure of the accumulator reaches a predetermined pressure, the accumulated pressure is used as the pilot pressure for the first unload control. By unloading the hydraulic pump by the valve, the accumulated pressure of the accumulator can be maintained substantially constant. Further, when the flow rate of the throttle means increases due to the increase of the discharge amount of the hydraulic pump, the pressure loss of the throttle means increases the differential pressure between the upstream side and the downstream side, and when the differential pressure reaches a predetermined differential pressure. By using the differential pressure as the pilot pressure and the second unload control valve unloads the hydraulic pump, it is possible to prevent the surplus load from increasing. According to the hydraulic pressure supply device of the second aspect of the present invention, by integrating the first unload control valve and the second unload control valve, the hydraulic circuit and parts can be shared between them. Therefore, the number of parts can be reduced and the circuit can be simplified, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing a schematic configuration of a hydraulic pressure supply device according to a first embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram showing a schematic configuration of a hydraulic pressure supply device according to a second embodiment of the present invention.

FIG. 3 is a time chart showing the operation of the hydraulic pressure supply device of FIG.

FIG. 4 is a circuit diagram showing a schematic configuration of a conventional hydraulic pressure supply device.

[Explanation of symbols]

8 Hydraulic supply device 9 hydraulic pump 10 Accumulator 11 1st unload control valve (unload means) 12 2nd unload control valve (unload means) 17 Aperture (diaphragm means) 18 Check valve 31 Hydraulic supply device 32 Unload control valve (unload means)

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Claims (2)

[Claims] 1. A hydraulic pump, an accumulator connected to the hydraulic pump via a throttle means and a check valve, and an unloading means for unloading the hydraulic pump, the unloading means comprising: When the accumulated pressure of the accumulator is used as a pilot pressure and the accumulated pressure reaches a predetermined pressure, the hydraulic pump is unloaded.
From an unload control valve and a second unload control valve that unloads the hydraulic pump when the differential pressure reaches a predetermined differential pressure, with the differential pressure between the upstream side and the downstream side of the throttle means being the pilot pressure. A hydraulic pressure supply device characterized in that 2. The first unloading control valve and the second unloading control valve are integrated with each other.
The hydraulic pressure supply device according to.