JPS61268885A - Capacity control device for variable delivery pump - Google Patents

Abstract

PURPOSE:To improve the work efficiency of a variable delivery pump as well as facilitate the fluid piping layout through eliminating the need of a fluid passage particularly for controlling the pump by controlling a variable delivery means in response to the differential pressure across a variable throttle which is interposed within the discharge-side fluid passage in the pump. CONSTITUTION:In the case where the fluid discharged from a variable delivery pump 100 is to be transmitted through a fluid passage 200, in which a switching valve 301 is interposed, to a driven actuator 300, such as the power cylinder of a power steering system, a variable throttle 400 is interposed somewhere along the fluid passage 200. This variable throttle 400 is controlled in response to the pressure Pi present downstream from said variable throttle 400. In addition, a variable delivery means 500 for the pump 100 is provided with No.1 and No.2 driving pistons 501, 602, and each of the two pistons 501, 502 is driven by the working fluid passing through a pressure detecting means 600 which is controlled in response to the differential pressure across the variable throttle 400. Thereby, the discharge quantity of the pump 100 can be controlled to increase the decrease.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a displacement control device for a variable displacement pump, and is effective for use in, for example, a power steering device of an automobile. When the power steering device requires a large amount of working fluid, the amount discharged from the pump is increased; conversely, when the power steering device requires only a small amount of working fluid, the amount discharged from the pump is decreased. let

[Conventional technology]

Conventionally, various types of capacity control devices of this type have been proposed. In particular, since the power consumption of a drive source that drives a pump is determined by the product of the pump's discharge pressure and discharge amount, a device has been proposed that controls this product to a constant value to efficiently drive the pump. For example, JP-A-58-1108
There is an apparatus described in Japanese Patent No. 81.

However, in this type of device, the throttle used for capacity control is provided separately from the fluid passage that supplies working fluid from the pump to the driven actuator.

That is, a throttle for capacity control is provided on a signal passage separate from the fluid passage, and the capacity of the pump is variably controlled based on the flow rate flowing in this signal passage. Therefore, a signal working fluid must always flow through the signal path. In particular, the working fluid for this signal requires a flow rate proportional to that of the working fluid flowing through the fluid passage, so when it is necessary to flow a large amount of working fluid through the fluid passage, it is necessary to Fluid is required. Therefore, this conventional device has the problem of wasting energy. At the same time, there is also the problem that a signal passage must be provided in addition to the fluid passage, which complicates the overall structure of the device.

[Problem that the invention seeks to solve]

The present invention was devised in view of the above points, and an object of the present invention is to control the discharge capacity of a pump based on the actual amount of working fluid flowing through a fluid passage without requiring a special signal passage. .

At the same time, it is an object of the present invention to control the amount of working fluid guided to the driven actuator so as to maintain good pump efficiency.

That is, an object of the present invention is to control the amount of working fluid guided to a driven actuator by varying the pump discharge capacity while keeping the product of the pump discharge pressure and the discharge volume constant.

In addition, the present invention controls the amount of working fluid supplied to the driven actuator with the pump's variable capacity and variable throttle while maintaining the best pump efficiency, and further supplies the working fluid to the driven actuator using the auxiliary variable throttle. Another object of the present invention is to make it possible to adjust the amount of working fluid applied.

A further object of the present invention is to enable a driven actuator to be well controlled even when the discharge capacity of the pump is minimized.

[Means for Solving the Problems and Their Effects] In the present invention, the amount of working fluid Q supplied to the driven actuator is defined as (as shown in equation 11) the opening area S of the fluid passage and the Considering that it is obtained by the product of the pressure difference ΔP before and after the throttle, Q=S・Δpi/!
・・・・・・・・・・・・・・・・・・ (1) By controlling the discharge capacity of the pump, the differential pressure ΔP between the front and rear is kept constant, and the fluid pressure guided to the driven actuator is A configuration is adopted in which the opening area S is varied based on this.

That is, the present invention provides a pump having a variable capacity means, a fluid passage for guiding fluid discharged from the pump to a driven actuator, a variable throttle disposed in the middle of the fluid passage, and a pressure difference across the variable throttle. and pressure detection means for detecting the pressure. Based on the signal from the pressure detection means, the pump varies its capacity so that the differential pressure ΔP before and after the pump is constant. At the same time, the variable throttle varies the opening area of the working fluid based on the pressure of the working fluid supplied to the driven actuator, that is, the working fluid pressure downstream of the variable throttle.

In the second aspect of the present invention, by disposing an auxiliary variable throttle in the fluid passage, the amount of working fluid Q supplied to the driven actuator can be separately controlled. Therefore, in the second invention, the working fluid itQ, which has become constant based on the configuration of the first invention, can be adjusted and controlled based on other auxiliary signals.

In the third aspect of the present invention, the variable throttle is provided with a relief groove portion that allows a minute amount of the working fluid in the fluid passage to escape. This is based on the following reasons.

Since the pump varies its discharge capacity based on the signal from the pressure detection means, especially when the opening area of the variable throttle becomes small, the pump discharge capacity also becomes small. Furthermore, it is known that the pressure of fluid discharged from a pump pulsates as a piston or the like moves. Particularly when the pump is operated at a small capacity, this pulsation of the discharge pressure has a large effect. That is, the relative influence of the discharge pressure pulsations increases, and as a result, relatively large pressure pulsations are also applied to the driven actuator, impairing good operation of the driven actuator.

Therefore, in the third invention, even if the variable throttle closes or is close to closing the fluid passage, a predetermined amount of working fluid is discharged from the pump, thereby reducing the discharge pulsation of the pump when the volume is small. It alleviates the impact of

〔Example〕

A first embodiment of the present invention will be described below based on the drawings.

FIG. 1 shows a schematic configuration of this first embodiment.
0 is a pump, and 200 is a fluid passage that guides the working fluid discharged from the pump 100 to the driven actuator 300. In this embodiment, a power cylinder of a power steering device of an automobile is used as the driven actuator. 301 is a switching valve that switches the working fluid guided to this power cylinder.

400 is a variable throttle arranged in the middle of the fluid passage 200,
It is controlled based on the pressure of the fluid supplied to the power cylinder 300, that is, the pressure Pi downstream of the variable throttle 400.

401 is a pressure guiding passage that guides the operating pressure Pi to the variable throttle 400.

Reference numeral 500 denotes a variable capacity means for varying the discharge capacity of the pump 100, and in this example, first and second drive pistons 501 and 502
Equipped with This pressure variable means 500 is a pressure detecting means 60
It is driven based on the oil pressure signal from 0. That is, when high pressure is introduced into the first drive piston 501 and low pressure is introduced into the second drive piston 502 from the pressure detection means, the variable displacement means 500 increases the discharge capacity of the pump 100.

Conversely, when the pressure is lower than that of the pressure detection means, the first drive piston 501
When high pressure is introduced into the second drive piston 502, the variable displacement means 500 decreases the displacement of the pump 100.

The pressure detection means includes first and second signal pressure passages 601.60.
2, the pressure around the variable throttle 400 is introduced. Then, the difference in pressure led from the signal pressure passages 601 and 602, that is, the pressure difference before and after the variable throttle 400 is detected. Based on this differential pressure, the pressure supplied to the variable capacity means is controlled as described above.

FIG. 2 shows the configuration shown in FIG. 1 more or less concretely. Pump 100 receives driving force from automobile engine 700 via electromagnetic clutch 701 to rotate. The pump 100 also sucks working fluid from the reservoir 750 through the suction passage 751.

The variable throttle 400 includes a sliding piston 404,
This sliding piston 404 is slidably disposed within a cylinder portion 403 formed in the middle of the fluid passage 200 in a direction perpendicular to the fluid passage. A passage portion 405 is formed in the sliding piston 404, and the fluid path can be varied depending on the area of the portion of the passage portion 405 that faces the inner fluid passage 200.

That is, in a state where many passage portions 40 and 5 face the fluid passage 200, the amount of restriction of the variable throttle 400 is small.

On the other hand, in a state where the passage portion 405 only slightly faces the fluid passage 200, the amount of restriction of the variable throttle 400 is large.

The sliding piston 404 is connected to the cylinder portion 403 and the piston 4.
The piston slides from side to side in the figure due to the pressure of the working fluid introduced into the pressure chamber 406 formed by the rear end of the piston 404 and the setting force of a spring 407 disposed at the other end of the piston 404. A variable throttle 40 is connected to the pressure chamber 406 via the pressure guiding passage 401.
0 downstream pressure Pi is introduced. Therefore, when the pressure Pi exceeds the set force of the spring 407, the piston 404 moves to the right in the figure based on the pressure, thereby reducing the opening area of the fluid passage.

The pressure detection means 600 includes a pressure chamber 610 formed in the housing, a switching valve section 611 slidably disposed within the pressure chamber, a pressure guiding hole 612 that guides high pressure to the pressure chamber, and a pressure chamber 610. Exhaust hole 613 to release more pressure to the outside.
614, a first pressure passage 620 communicating with the first drive piston 502 of the variable displacement means, and a second pressure passage 621 communicating with the second drive piston 502.

Of the pressure chambers 610, a first pressure chamber 63 at the right end in the figure
0, the fluid pressure Pi downstream of the variable throttle 400 is introduced via the first signal path 601.

Also, a second pressure chamber 631 at the left end in the figure among the pressure chambers 610
The variable throttle 400 is connected via the second signal pressure passage 602.
An upstream pressure Pd is introduced. Further, a spring 640 having a predetermined set pressure is disposed within the first pressure chamber 630. Therefore, the differential pressure ΔP before and after the variable throttle 400 introduced via the signal passages 601 and 602 and the spring 64
Due to the setting force of 0, the switching valve section 611 opens the pressure chamber 610.
Slide inside to the left and right in the diagram.

The switching valve portion 611 includes first and second communication portions 650.6.
51 is formed, and the first and second communication portions 650 .
651, the pressure guiding hole 612 and the first and second pressure passages 620
．． 621, and between the exhaust pressure holes 613 and 614 and the first and second pressure passages 620 and 621.

4 and 5 illustrate one embodiment of pump 100. FIG.

In the figure, 101 is a shaft that rotates by receiving the rotational force of an automobile engine 700 via an electromagnetic clutch 701, and 102 is a bearing that rotatably supports this shaft, which is supported by a housing 103. 104 is a bottle that is oil-tightly coupled to the main housing 900 via a spring 105, and this main housing 900. Bintle 10
A cylindrical working space 106 between 4 and the housing 103
is formed. Reference numeral 107 denotes a rotating ring disposed within the working space, which is comprised of an outer race 10B held by the inner surface of the main housing 900, an inner race 109, and a large number of balls 110 disposed between both races 108 and 109. Become.

The bottle 104 is provided with a central protrusion 111 that discharges to the working space 106 side, and this central protrusion 111
A rotor 113 is rotatably supported via a bush 112. Note that the rotor 113 is connected to the shaft 101
It rotates as one. Six cylinders 114 are formed radially within the rotor 113, and a piston 115 is slidably disposed within the cylinders 114. 116
is a spring that presses the piston 115 outward, and the tip of the piston 115 is always in contact with the inner race 109.

The bottle 104 includes a suction passage 120 and a discharge passage 12.
1 are formed, each opening toward the rotor 113 at a central protrusion 111. That is, the suction passage 12
0 is opened at a portion of the rotor 113 corresponding to the suction stroke by a suction communication groove 122, while a discharge passage 121
The discharge communication groove 123 is opened at a portion of the rotor 113 corresponding to the discharge stroke.

The main housing 900 is formed with first and second holding parts 150 and 151 that slidably hold the first driving piston 501 and the second driving piston 502. Inside these holding parts 150 and 151 are springs 152, respectively.
．． 153 is arranged, both springs 152.15
3 connects the drive piston 501.502 to the outer race 10
Press to the 8 side.

The first pressure passage 620 and the second pressure passage 621 described above are each formed within the main housing 900, and their tips communicate with the first and second holding parts 150 and 151. Further, the opening ends of both the holding parts 150 and 151 are closed by blind screws (not shown), and the main housing 90
A closed space is formed within 0.

Pressure detection means 600 is formed within main housing 900. That is, a pressure chamber 610 is formed within the main housing 900, and a switching valve portion 611 is slidably disposed in this pressure chamber 610. In addition, the pressure chamber 6
10 is closed by a blind screw 170 to form a closed space. Furthermore, in addition to the first and second pressure passages 620 and 621 described above, the second signal passage 602 that guides signal pressure to the pressure guiding passage 612 and the second pressure chamber 631 is also connected to the main housing 90.
It is formed within 0. Exhaust pressure passages 613 and 614 are also formed within the main housing 900, and these exhaust pressure passages communicate with the working space 106.

As shown in FIG. 6, a protrusion 645 is formed at the left end of the switching valve part 611 in the drawing, and this protrusion 645 is connected to the receiving part 6 formed in the main housing 900.
46. The tip of the protrusion 645 is tapered, so when the protrusion 645 is fitted into the receiver 646, the working fluid in the receiver 646 flows through the tapered part. It flows out to the first pressure chamber 630 side. During this outflow, the flow of the working fluid is restricted by the narrow gap between the taper part and the receiving part 646, and the flow of the working fluid is obstructed. Therefore, a situation in which the switching valve part 611 suddenly fits into the receiving part 646 is prevented.

In the example illustrated in FIG. 6, a portion of the taper is formed at the tip of the protruding portion 645, but as shown in FIG. 7, a portion of the taper may be formed on the portion 646 side of the receiver. Furthermore, a ring 648 having a large number of pores 647 as shown in FIG.
In this case, as shown in FIG. The throttling effect of the hole 647 prevents sudden movement of the switching valve section 611. In the embodiment shown in FIG. 9, the spring 6
40 is not disposed within the first pressure chamber 630, but the receiver is disposed within the portion 646.

A variable aperture 400 is disposed within the bottle 104. That is, as shown in FIG. 4, the discharge passage 121 in the bottle 104 also forms a fluid passage 200,
Therefore, a variable throttle 400 is disposed within this discharge passage 121. Therefore, although not shown, a pressure guiding passage 401 that guides the pressure Pi downstream of the variable throttle 400 is also formed within the bottle 104.

Note that the opening area of the variable throttle 400 is determined by the pressure Pi downstream of the throttle.
It changes as shown in Figure 3 depending on the situation. That is, the pressure Pi
is smaller than the set load PO of the spring 407, the piston 404 is not displaced and therefore the passage portion 405 maintains its maximum opening area (between AB in the figure). The pressure Pi is set in the cylinder @P.

When the piston 404 becomes larger, the piston 404 moves to the right in FIG. 2, and with this movement, the opening area of the passage portion 405 decreases (between 8C in the figure).

Corresponding to the throttle amount of the variable throttle 400, the flow rate of the working fluid downstream of the throttle 400 also changes as shown in FIG. 1θ. Note that although the discharge amount increases between Nos. in FIG. 10, this is not based on a change in the opening area of the variable diaphragm 400;
This is based on the change in discharge amount when the pump 100 starts up. That is, when the discharge pressure is low, the force due to the pressure of the working fluid applied to the first drive piston 501 and the second drive piston 502 is smaller than the load caused by the springs 152 and 153. This is the spring 152,1
This is because the rotation ring 107 is positioned on the side where the capacity of the pump 100 is smaller due to the balance of the loads of the pumps 53 and 53. Note that the set load of the spring 152 is greater than that of the spring 153. As a result, the discharge amount decreases.

Here, the characteristics in FIG. 3 and FIG. 10 are similar, and this is due to the following reason.

As described above, the flow rate Q of the working fluid flowing through the variable throttle 400 is determined by its opening area S and the differential pressure ΔP.

Q=cd-3(2/ρ)・(Pd-Pi)・・・・・・
(2) Since Cd is the flow coefficient and ρ is the density of the working fluid, they are considered to be approximately constant. Also, the differential pressure between the front and rear of the pump is
The discharge volume of 00 is controlled to be variable and always constant. Therefore, equation (2) expresses that the flow rate Q is almost uniquely determined by the opening area S of the variable throttle 400.

In this example, in order to maximize the operating efficiency of the pump 100, the product of the discharge flow rate (flow rate Q) and the discharge pressure P (PXQ
The shape of the passage portion 405 of the variable diaphragm 400 is determined so that ) is constant.

FIG. 11 is a graph showing the shape of this passage portion 405, and the horizontal axis represents the moving direction of the piston 404. Therefore, when the shape of this passage section 405 is expressed as Y=f (x), the opening area of the passage section 405 is obtained by the following equation.

”2 (F (xm) F (Xo) ) +Cs
(3) The shape of the passage portion 405 is determined by this equation (3) and the above-mentioned condition, that is, PXQ is constant.

Note that, as shown in FIG. 11, the tip of the passage portion 405 does not have the shape obtained from the above formula, but has an arcuate portion 480. This is because the opening area of the passage portion 405 is rapidly reduced when the piston 404 has moved by the maximum amount. The area between CD in FIG. 3 and the area between No in FIG. 10 corresponds to this arcuate portion 480.

The shape shown in FIG. 11 is the most desirable in terms of minimizing the power consumption of the pump 100, but it goes without saying that other shapes may be used. FIG. 12 is a straight line approximation of the curve shown in FIG. 11. As a result, in the shape shown in FIG. 12, the passage portion 405 can be easily formed. The characteristics already indicated by the broken lines in FIGS. 3 and 10 are examples using the passage section 405 having the shape shown in FIG. 12.

Furthermore, as shown in FIG. 13, the passage portion 4o5 may be formed in one straight line.

On the other hand, the tip of the passage portion 405 does not have to be an arcuate portion 480 as shown in FIG. 11, but may have a shape as shown in FIGS. 14 and 15. In this case, a discharge amount characteristic as shown in FIG. 16 is obtained. The solid line l in FIG. 16 is the characteristic of the arcuate portion 480 shown in FIGS. 11 to 13, the solid line m is the tip 481 in the state shown in FIG. 01 example.

Next, the operation of the apparatus having the above configuration will be explained.

When the shaft 101 receives the driving force from the engine and rotates within the housing 103, the rotor 113 also rotates on the shaft 101.
Rotates in sync with. At this time, since the rotor 113 is surrounded by the rotating ring 107 and the center line of the rotating ring 107 and the center line of the rotor 113 are eccentric, the piston 115 reciprocates within the cylinder 114 as the rotor 113 rotates. Note that the amount of reciprocating movement of the piston 115 is equal to 2 of the amount of eccentricity between the rotor 113 and the rotating ring 107.
It will be doubled.

As the piston 115 reciprocates, the volume of the pressure chamber space 190 surrounded by the piston 115 and the cylinder 114 increases or decreases. During the suction stroke in which the pressure chamber 190 expands in volume, the working fluid sucked from the suction passage 120 flows into the suction communication groove 1.
22 into the pressure chamber 190. In the discharge stroke in which the pressure chamber 190 decreases in volume, the pressure chamber 190
The working fluid in the discharge passage 12 is passed through the discharge communication groove 123.
1.

As described above, the reciprocating stroke of the piston 115 is varied depending on the amount of eccentricity between the rotary ring 107 and the rotor 113. In this example, first and second
Drive pistons 501, 502 are arranged, and in response to the movement of both pistons 501, 502, the rotary ring 10
7 is also displaced in the left-right direction in FIG. When the rotary ring 107 moves rightward in the drawing (the state shown in FIG. 5), the amount of eccentricity is the largest, and therefore the volume variation of the pressure chamber 190 is also the largest. Therefore, in this state, the discharge amount from the pump 100 is maximum. Conversely, the rotating ring 107
When the pump 100 moves to the left in the figure, the amount of eccentricity decreases with the movement, and therefore the discharge amount of the pump 100 also decreases.

In this example, the discharge amount of the pump 100 is determined by the pressure detection means 600 and the variable capacity means 500 by the variable throttle 400.
The pressure difference between the front and rear of the pump is controlled so that it is always constant. That is, the pressure Pi downstream of the variable throttle 400 is the first signal pressure passage 6.
The pressure detecting means is introduced into the first pressure chamber 630 via the signal pressure passage 602, and the pressure Pd upstream of the variable throttle 400 is introduced into the second pressure chamber 631 via the second signal pressure passage 602. 1st
Since the pressure chamber 630 and the second pressure chamber 631 face each other, a differential pressure (Pd-Pi) is applied to the switching valve section 611. The switching valve section 611 is moved by this differential pressure and the setting force of the spring 640.

When the differential pressure is less than the set force of the spring 640, the spring 640 presses the switching valve portion to the right in FIG. Therefore, the pressurized working fluid discharged from the pressure chamber 190 passes from the pressure guiding hole 612 to the first passage portion 651.
A pressure passage 620 is supplied thereby applying high pressure to the back of the first drive piston. At the same time, the back pressure of the second drive piston 502 is transferred from the second pressure passage 621 to the communication portion 650.
and is returned to the space 106 side of the pump 100 through the exhaust pressure hole 614. Therefore, the rotating ring 107 is pushed by the first driving piston in a direction that increases its eccentricity. Therefore, when the differential pressure is small, the discharge amount of the pump 100 is increased.

When the pump discharge is increased, the result is that the variable throttle 400
The differential pressure before and after increases. When the differential pressure exceeds the set pressure of the spring 640, the switching valve part 611 releases the spring 64.
0 to the left in FIG. Then, the discharge pressure of the pump 100 flows from the pressure guiding hole 612 to the second pressure passage through the communication part 650, leading to high pressure to the back surface of the second driving piston. Also, the back pressure of the first drive piston 501 is
It is released to the space 106 side of the pump 100 via the pressure passage 620, the communication portion 651, and the exhaust pressure hole 613. Therefore, the rotary ring 107 is pressed by the second driving piston in a direction that reduces its eccentricity. Therefore, variable aperture 4
If the differential pressure across 00 increases, the pump 100 decreases the discharge amount.

By repeating the above operations, the pump 100 variably controls its discharge capacity so that the differential pressure across the variable throttle 400 is always constant.

The opening area of the variable throttle 400 is variably controlled by the pressure Pi downstream of the throttle. Here, the pressure Pi downstream of the throttle indicates the fluid pressure supplied to the power cylinder 300 of the power steering device. Particularly in a power steering device, in a state where a large amount of working fluid is required, such as during steering operation, the working fluid pressure does not need to be very high.

However, high pressure is required when steering the steering wheel to its limit and holding it there, or when it is necessary to hold the steering wheel strongly when driving on rough roads.
Doesn't require much fluid.

In other words, the characteristics of the working fluid supplied to the power cylinder 300 are as shown in FIG. A large discharge amount is required under normal discharge pressure, but when a high discharge pressure is required, the required discharge amount decreases. In particular, when the required discharge pressure is at its maximum, almost no discharge amount is required.

In this example, since the variable throttle controls the opening area of the fluid passage 200 based on the pressure Pi of the fluid supplied to the power cylinder 300, the above-mentioned characteristics can be obtained satisfactorily.

Moreover, in this example, the variable throttle 400 controls the opening area so that the product of the pressure P and the flow rate Q of the fluid discharged from the pump 100 is constant, so the operating efficiency of the pump 100 is maintained at its best. Ru.

FIGS. 17 and 18 show an embodiment according to the second aspect of the present invention.

In this embodiment, an auxiliary variable diaphragm 800 is further provided downstream of the variable diaphragm 400, and the other configurations are the same as those of the above-described embodiment. The variable throttle 400 introduces the fluid pressure Pi downstream of the auxiliary variable throttle 800 via the pressure guiding passage 401 . Further, the pressure detection means 600 detects the fluid pressure Pi downstream of the auxiliary variable throttle 800 and the pressure Pd upstream of the variable throttle 400 in a first manner.
The second signal pressure is introduced via the pressure channel 601.602.

Therefore, in this embodiment as well, the discharge capacity of the pump 100 is controlled so that the differential pressure across both the variable throttles 400 and 800 is constant, and the variable throttle 400
Control is performed so that the product of the zero discharge pressure P and the discharge flow rate Q is constant.

In this example, since the auxiliary variable throttle 800 is further provided on the above structure, the flow rate supplied to the power cylinder 300 can be controlled more precisely by the auxiliary variable throttle 800. The auxiliary variable diaphragm 800 is an electromagnetic solenoid 801
The aperture amount is varied, and the electromagnetic solenoid 801 is driven based on an electric signal from the control section 802. Signals from a vehicle speed sensor 803, a steering angle sensor 804, etc. are input to the control unit 802, and the optimal flow rate of the working fluid supplied to the power cylinder 300 is calculated based on these signals.

Based on this calculation result, an electric signal is supplied to the electromagnetic solenoid, thereby controlling the aperture amount of the auxiliary variable aperture 800.

FIGS. 19 and 20 explain an embodiment according to the third aspect of the present invention. In this embodiment, a relief groove portion 45 that communicates the relief portion 450 of the variable throttle 400 with the passage portion 405 is used.
1, and the other configurations are the same as those of the above-mentioned embodiment.

As described above, in the present invention, the discharge flow rate Q of the pump 100
is controlled according to the characteristics of the working fluid supplied to the power cylinder 300, so especially when the working fluid pressure is at its maximum (N in FIG. 10), the discharge amount required of the pump 100 is almost constant. becomes close to zero. This can be achieved by reducing the amount of eccentricity of the rotating ring 107 to almost zero using the variable capacity means 500.

However, since the pump compresses and discharges the fluid by varying the volume of the plurality of pressure chambers 190, discharge pulsations inevitably occur due to this volume variation. If the popn 100 has a sufficient discharge capacity, this discharge pulsation does not pose a problem, but when the discharge capacity of the pump 100 is extremely small as described above, the influence of this discharge pulsation becomes relatively large.

Therefore, in this example, a predetermined amount of working fluid is transferred to the relief groove 451 even if the passage 405 of the variable throttle 400 almost closes the fluid passage 200.
I let it flow to the side.

That is, the relief groove compensates for the minimum discharge capacity of the pump 100. Note that the working fluid led out to the relief part 450 by the relief groove part 451 is then transferred to the pump 1.
00 space 106 or the reservoir tank side.

The relief groove 451 is formed on the outer periphery of the sliding piston 404 in the pump shown in FIG. 1, but in the pump shown in FIGS.
As shown in the figure, it may be formed on the bottle 104 side of the pump 100. Even in this case, the relief groove portion 451 is formed at a position where the passage portion 405 of the variable throttle 400 leads out the working fluid to the relief portion 450 side while the fluid passage is restricted to the maximum extent.

In the above example, a so-called radial plunger pump was used as the pump 100, but it goes without saying that other types of pumps may be used.

Basically, any type of pump can be used as long as it has a variable capacity function.

At the same time, the drive source for the pump 100 is not limited to the vehicle running engine 700 described above, but may also be a motor or the like.

Further, in the above example, the pressure detection means 600 also directly introduces pressure through the signal pressure passages 601 and 602, but it also converts the pressure into an electrical signal using a pressure sensor or the like, and converts the pressure into an electrical signal. It may be configured to detect and compare.

Similarly, the variable diaphragm 400 may be not only a mechanically variable diaphragm using a spring 407, but also a diaphragm that can be electrically controlled using an electromagnetic solenoid or the like.

Furthermore, it goes without saying that the device of the present invention has various uses other than the power steering device described above.

〔Effect of the invention〕

As described above, the device of the present invention controls the discharge amount of the pump using the working fluid supplied to the driven actuator, and therefore does not require a special fluid passage for pump control. Therefore, the entire fluid piping becomes easy and the work efficiency of the pump is also improved.

Further, according to the present invention, since the discharge capacity of the pump can be variably controlled while the pump efficiency is maintained at approximately the optimum level, the pump efficiency is always kept in a good state.

Furthermore, in the second aspect of the present invention, the flow rate of the working fluid supplied to the driven actuator can be arbitrarily adjusted while maintaining the discharge efficiency of the pump in a good state.

In the third aspect of the present invention, even when the discharge capacity of the pump is reduced, the influence of the discharge pulsation of the pump can be suppressed. Therefore, the driven actuator can always be well controlled.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing an embodiment of the device according to the first aspect of the present invention, FIG. 2 is a schematic explanatory diagram of the device illustrated in FIG. 1, and FIG. 3 is a characteristic of the switching valve illustrated in FIG. 1. FIG. 4 is a sectional view of the pump shown in FIG. 1, and FIG. 5 is a cross-sectional view of the pump shown in FIG.
6 is a sectional view showing a main part of the pressure detection means shown in FIG. 1; FIG. 7 is a sectional view showing another example of the pressure detection means shown in FIG. 6; FIG. 8 is a front view showing the main parts of still another example of the pressure detection means, FIG. 9 is a sectional view showing the pressure detection means using the ring shown in FIG. 8, and FIG. 10 is the pump shown in FIG. 1. An explanatory diagram showing the relationship between discharge amount and discharge pressure, FIG. 11 is an explanatory diagram showing the shape of the passage section of the variable throttle shown in FIG. 1, and FIGS. 12 to 15 each show other shapes of the passage section. An explanatory diagram, FIG. 16 is an explanatory diagram showing the characteristics of the cut section shown in FIGS. 11 to 1, and FIG. 1
8 is a sectional view of the pump shown in FIG. 1. FIGS. 19 and 20 are sectional views showing the variable throttle of the device according to the third aspect of the present invention, and FIGS. 21 and 22 are sectional views of the pump shown in FIG.
It is a sectional view showing other examples of the illustrated pump. 100... Pump, 200... Fluid passage J 300
...Driven actuator, 400...Variable aperture,
50O... Capacity variable means, 600... Pressure detection means. Representative Patent Attorney Takashi Okabe Figure 1 RO±, Koni Pressure P Figure 10! Figure 3Figure 17Figure 22

Claims (1)

[Scope of Claims] 1. A pump that compresses and discharges a working fluid, a variable capacity means that controls the discharge volume of this pump, a fluid passageway that guides the working fluid discharged from the pump to a driven actuator, and The variable capacity means includes a variable throttle disposed in the middle of the fluid passage to vary the fluid passage area, and pressure detection means for detecting pressure before and after the variable throttle, and the variable capacity means detects the variable throttle based on a signal from the pressure detection means. The discharge capacity of the pump is varied so that the differential pressure between the front and rear sides is always substantially constant, and the variable throttle is based on the pressure downstream of the variable throttle, and when the pressure increases, the fluid passage area is reduced, and when the pressure decreases, the fluid passage area is reduced. A displacement control device for a variable displacement pump configured to increase fluid passage area. 2. The pressure detection means detects the pressure downstream of the variable throttle and the pressure upstream of the variable throttle, and when the differential pressure therebetween is greater than a predetermined pressure, sends a signal to the variable displacement means to reduce the discharge capacity of the pump. 2. A displacement control device for a variable displacement pump according to claim 1, wherein a signal is derived to said variable displacement means to increase the discharge displacement of said pump when said differential pressure is equal to or lower than a predetermined pressure. 3. The pump includes a rotary ring, a rotor eccentrically disposed within the rotary ring, a cylinder formed radially on the rotor, and a cylinder disposed slidably within the cylinder, the tip of which is disposed eccentrically within the rotary ring. The variable displacement pump according to claim 1, further comprising a piston that abuts an inner surface of a ring, and the piston slides back and forth within the cylinder as the rotor rotates to compress and discharge working fluid. Capacity control device. 4. The variable capacity means includes a driving piston disposed outside the rotating ring, and the driving piston moves the rotating ring to vary the amount of eccentricity between the rotating ring and the rotor. 4. The variable displacement pump capacity control device according to claim 3, which controls the discharge capacity of the pump. 5. The pressure detection means is configured to detect a pressure difference between the rotary ring and the rotor to the drive piston of the variable displacement means when the pressure difference is large between the pressure upstream of the variable throttle and the pressure downstream of the variable throttle. A drive signal is derived to reduce the amount of eccentricity between the rotating ring and the rotor, and when the differential pressure is small, a drive signal is derived to increase the amount of eccentricity between the rotary ring and the rotor to the drive piston of the variable displacement means. 4. A capacity control device for a variable capacity pump according to item 4. 6. The variable capacity means includes a first drive piston and a second drive piston disposed outside the rotating ring, and the pressure detection means derives a drive signal to the first drive piston. A patent comprising a four-way valve that performs switching between a first signal pressure passage that outputs a drive signal to the second drive piston, a second signal pressure passage that derives a drive signal to the second drive piston, a pressure guide passage that introduces high pressure, and a discharge pressure passage that discharges high pressure. A capacity control device for a variable capacity pump according to claim 5. 7. A pump that compresses and discharges a working fluid, a variable capacity means that controls the discharge volume of this pump, a fluid passage that guides the working fluid discharged from the pump to a driven actuator, and a fluid passage disposed in the middle of the fluid passage. a variable throttle that changes the area of the fluid passage; an auxiliary variable throttle that is disposed in series with the variable throttle in the middle of the fluid passage; and pressure detection means that detects pressure before and after the variable throttle; The means varies the discharge capacity of the pump so that the differential pressure before and after the pressure detecting means is always substantially constant based on the signal from the pressure detecting means, and the variable throttle adjusts the pressure based on the pressure downstream of the variable throttle. If the pressure increases, the fluid passage area is decreased, and if the pressure decreases, the fluid passage area is increased, and the auxiliary variable throttle changes the passage area of the fluid passage based on the auxiliary signal, thereby increasing the amount of working fluid guided to the driven actuator. a displacement control device for a variable displacement pump configured to adjust the displacement of the pump; 8. The pressure detection means detects the pressure downstream of the variable throttle and the pressure upstream of the variable throttle, and when the differential pressure therebetween is greater than a predetermined pressure, sends a signal to the variable displacement means to reduce the discharge capacity of the pump. 8. The displacement control device for a variable displacement pump according to claim 7, wherein the variable displacement pump outputs a signal to the variable displacement means to increase the discharge displacement of the pump when the differential pressure is equal to or lower than a predetermined pressure. 9. The pump includes a rotary ring, a rotor eccentrically disposed within the rotary ring, a cylinder formed radially on the rotor, and a cylinder disposed slidably within the cylinder, the tip of which is disposed eccentrically within the rotary ring. The variable displacement pump according to claim 7, further comprising a piston that abuts an inner surface of a ring, and the piston slides back and forth within the cylinder as the rotor rotates to compress and discharge working fluid. Capacity control device. 10. The variable capacity means includes a driving piston disposed outside the rotating ring, and the driving piston moves the rotating ring to vary the amount of eccentricity between the rotating ring and the rotor. The capacity control device for a variable capacity pump according to claim 9, which controls the discharge capacity of the pump. 11. The pressure detection means is based on a pressure difference between the pressure upstream of the variable throttle and the pressure downstream of the variable throttle, and when the pressure difference is large, the pressure detection means causes the driving piston of the variable displacement means to connect the rotary ring and the rotor. A drive signal is derived to reduce the amount of eccentricity between the rotating ring and the rotor, and when the differential pressure is small, a drive signal is derived to increase the amount of eccentricity between the rotary ring and the rotor to the drive piston of the variable displacement means. 10
A capacity control device for a variable capacity pump as described in . 12. The variable capacity means includes a first drive piston and a second drive piston disposed outside the rotating ring, and the pressure detection means derives a drive signal to the first drive piston. A patent comprising a four-way valve that performs switching between a first signal pressure passage that outputs a drive signal to the second drive piston, a second signal pressure passage that derives a drive signal to the second drive piston, a pressure passage that introduces high pressure, and a pressure passage that discharges high pressure. Claim No. 11
A capacity control device for a variable capacity pump as described in . 13. The displacement control device for a variable displacement pump according to claim 7, wherein the variable amount of the auxiliary variable throttle is controlled by an electric actuator. 14. Capacity control of the variable displacement pump according to claim 13, wherein the variable throttle is configured to apply an electric signal based on the auxiliary signal to the electric actuator, and variably control the fluid passage area based on the electric signal. Device. 15. A pump that compresses and discharges a working fluid, a variable capacity means that controls the discharge volume of this pump, a fluid passage that guides the working fluid discharged from the pump to a driven actuator, and a fluid passage disposed in the middle of the fluid passage. and a pressure detection means for detecting pressure before and after the variable throttle; the variable throttle includes a sliding piston slidably disposed in a direction transverse to the fluid passage; , a passage portion formed in the sliding piston, a relief portion for releasing the working fluid in the fluid passage to the outside, and a relief groove connecting the relief portion and the passage portion; The opening area of the passage section opening into the fluid passage is variably controlled as the passage section moves, and the variable capacity means is configured to control the pressure difference so that the differential pressure before and after the pressure detection means is always approximately constant based on a signal from the pressure detection means. The discharge capacity of the pump is varied, and the variable throttle is configured to reduce the fluid passage area when the pressure increases and increase the fluid passage area when the pressure decreases based on the pressure downstream of the variable throttle. Pump capacity control device. 16. The variable throttle is configured such that when the passage section has an opening area of the fluid passage equal to or less than a predetermined value, the relief groove section releases the working fluid in the fluid passage to the relief section. Capacity control device for variable displacement pumps. 17. The capacity of the variable displacement pump according to claim 13, wherein the variable throttle is such that when the passage portion closes the fluid passage, the relief groove portion releases the working fluid in the fluid passage to the relief portion. Control device.