JPS6166872A - Variable-capacity pump - Google Patents

Abstract

PURPOSE:To obtain a compact apparatus by installing a sleeve onto the outer periphery of a piston which varies the amount of eccentricity of the guide ring of a variable-capacity pump and shifting the piston by controlling the pressure in a control hydraulic chamber through the slide of the sleeve. CONSTITUTION:When the revolution speed of the rotor 2 of a pump is low, the differential pressure DELTAP generated before and behind a variable throttle in a pump discharge conduit is small, and a sleeve 55 which can slide according to the differential pressure DELTAP is positioned in the upper part of an accommoda tion chamber 51 by a control spring 65. Since, in this state, a high-pressure hole 72 of the sleeve 55 communicates to a control groove 69 of a piston 52, the pressure of a pressure chamber 61, i.e., the pump discharge pressure is introduced into a control hydraulic chamber 59, and the piston 52 presses a guide ring 4 upwardly, and the amount of eccentricity (e) is made max. When the number of revolution of the rotor increases, and the differential pressure DELTAP increases over a set value, the sleeve 55 lowers, and the control hydraulic chamber 59 communicates to the low pressure inside the pump, and the amount of eccentricity (e) is rediced by the lowering of the piston 52.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Utilization Bone IF) The present invention relates to a variable displacement pump that controls the discharge flow rate.

(Prior Art) Conventionally, in order to control the discharge flow rate in this type of pump, it has been proposed that, for example, a control actuator that changes the ring eccentricity of a variable capacity vane pump is controlled by switching and operating a load sensing valve. (For example, JP-A-57
-157083, etc.) (Problems to be solved by the invention) However, in such a variable displacement pump, it is necessary to provide a load sensing valve, etc. in addition to the control actuator, which makes the configuration complicated and compact. There was a problem that it was difficult to provide a suitable pump.

The present invention has been made in view of the above points, and an object of the present invention is to provide a variable displacement pump that is compact and has a simple configuration.

(Means for Solving the Problem) Therefore, the present invention includes a rotor that is built in a housing and rotates, a guide ring provided on the outer periphery of the rotor, and a pump chamber volume that increases by changing the amount of eccentricity of the guide ring with respect to the rotor. In variable displacement pumps that change
A spring that presses the guide ring toward the center of the rotor in a direction that increases eccentricity, a piston that is biased by the internal pressure of a control hydraulic chamber into which pump discharge pressure can be introduced, and a piston that is provided around the outer circumference of the piston. a sleeve that slides based on a differential pressure generated in a flow control valve that throttles the flow rate from the pump and switches the control hydraulic chamber to pump discharge pressure or low pressure; and a sleeve that is supported by a part of the piston to control the flow rate. The above object is achieved by including a spring that biases against the differential pressure generated across the valve.

(Function) The pressure in the control hydraulic chamber is controlled by the piston, sleeve, etc. of the above-mentioned means, and the piston controls the amount of eccentricity of the guide ring based on the pressure.

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

Fig. 1 is a sectional view showing an embodiment of the present invention using a variable displacement radial plunger pump as a variable displacement pump, Fig. 2 is a sectional view taken along line A-A in Fig. 1, and Fig. 3 is a rotational view of the pump. Characteristic diagrams showing the relationship between the number and the discharge amount are shown.

In FIGS. 1 and 2, reference numeral 1. 5. 13 are a housing, a site housing, and a bottle, which form the outer shape of the pump, and the housing 1. Side housing 5. The bottle 13 is fixed together with a bolt 6.6'' via a sealing O-ring 24.25.

Inside the housing 1, etc., a rotor 2 is supported by a bottle 13 and is rotatably installed around a point O.
The rotor 2 is integrally fastened at a fastening portion 2a to a drive shaft 26 which rotates in response to external power (not shown), and rotates together with the drive shaft 26.

Are they arranged radially in rotor 2? flit cylinder holes 21 are bored, and each cylinder hole 21 has a
A plunger 3 urged outward from a center point O by a spring 22 is slidably inserted in an oil-tight manner. Inside the rotor 2, there is a plunger 3 and a cylinder hole 21.
A pump chamber 23 is formed in which the volume changes repeatedly.

A bushing 10 made of a sliding material such as phosphor bronze is driven into the inner circumference of the rotor 2, and the bushing 10 is fitted with a bottle 13 in an oil-tight manner and slidably rotatable. , rotates together with the rotor 2. The bushing 10 has the same number of communication holes 20 as the cylinder holes 21 and a smaller diameter than the cylinder holes 21. The bushing 10 supports one end of a spring 22 disposed inside the cylinder hole 21. There is.

On the other hand, on the outer periphery of the rotor 2, an inner ring 4a, an outer ring 4
A guide ring 4 consisting of one ball 4C is provided. Although the guide ring 4 is restricted from moving in the axial direction by the inner walls of the housing 1 and the side housing 5, it is possible to move in the radial direction.
The center 0' of can change the eccentricity e of the rotor 2 with respect to the center O.

The inner periphery of the inner ring 4a of the guide ring 4 is connected to the plunger 3.
The R-shaped part at the tip of the flj 4 corresponds to a roughly hemispherical shape.
a' is formed, and is in line contact with the tip of the plunger 3 and rotates at approximately the same speed as the rotor 2.

The outer periphery of the outer ring 4b is in contact with each roller 77.54 of a piston 75.52 (described later) disposed in the housing 1, and also in contact with a part of the inner wall of the housing l, so that the rotation of the rotor 2 It does not rotate with the

The bottle 13 has a discharge groove 1 extending over an angle corresponding to the discharge stroke that reduces the volume of the pump chamber 23 of the rotor 2.
4 is formed, and a suction -a15 is formed over an angle corresponding to the suction stroke in which the volume of the pump chamber 23 increases. During the suction stroke, in which the plunger 3 slides outward by the center of the rotor 2 (corresponding to approximately the left half of FIG. Suction groove 15 of pintle 13. Suction hole 17. It communicates with the tank 28 through the suction port 12 to suck oil into the pump chamber 23. Further, when the rotor 2 rotates in the downward circumferential direction in FIG. 2, the plunger 3 slides toward the center of the rotor 2, resulting in a discharge stroke. At this time, the pump chamber 23 is connected to the communication hole 20 of the bush 10 and the discharge iA14 of the bottle 13. Discharge hole 16. It communicates with the discharge port 11 and discharges the oil in the pump chamber 23.

A discharge hole 16 is provided on the outer periphery of the bottle 13 through a communication hole 18.
An annular oil passage a19 is formed which communicates with the oil passage groove 19, and the oil passage groove 19 communicates with the high pressure chamber 61 of the first control device 550 via the communication passage 27 of the housing 1.

The drive shaft 26 is supported by a journal bearing consisting of a reinforcing ring 7 and a sliding ring 8 press-fitted into the side housing 5. side housing 5
An oil seal 9 is provided around one end of the shaft 26 to prevent oil inside the pump from flowing out.

Next, a control device for changing the eccentricity e of the rotor 2 and the guide ring 4 will be explained.

On the lower side of FIGS. 1 and 2, there is a storage chamber 51 in the housing l.
is bored, and a cylindrical first piston 5 is installed inside it.
2 is slidably disposed.

The tip 52a of the first piston 52 is provided with an I-ra 53 that rolls into contact with the outer ring 4b of the guy 1 ring 4, and a no-yaf 1-54 that rotatably supports the roller 53. Further, since the tip 52a of the piston 52 is held in two planes by the housing l, the shaft 54, which is the rotational axis of the roller 53, is always parallel to the rotational axis of the guide ring 4, and the shaft 54, which is the rotational axis of the roller 53, is always parallel to the rotational axis of the guide ring 4. always rolls into contact.

A control cylinder 57 is oil-tightly disposed below the storage chamber 51 in the figure via an O-ring 56. An oil-tight control hydraulic chamber 59 is formed by the lower end surface 52b of the first piston 52 and the camp 58 which is screwed into the housing 1 through an O-ring 56 in an oil-tight manner. The first piston 52 is slidably fitted in an oil-tight manner with the control cylinder 57.

The sleeve 55 is disposed around the outer circumference of the first piston 52, and the inner and outer circumferential surfaces of the sleeve 55 are slidable in an oil-tight manner on the first piston 52 and the storage chamber 51, respectively. The discharge pressure of the discharge hole 16 is guided to the pressure chamber 61 formed in the upper end surface of the sleeve 55 via the oil passage 27, the oil passage groove 19, and the oil passage hole 18. Further, the pilot chamber 62 formed on the lower end surface communicates with the downstream side of the variable throttle 29, which is a flow rate control valve provided on the way from the discharge port to the hydraulic device (not shown), via the oil passage port 63. There is. Therefore, the sleeve 55 slides based on the differential pressure across the variable throttle 29 P (=P+-P2.P, where P2 is the upstream pressure of the variable throttle 29 and the downstream pressure of the P2 variable throttle 29). Further, the sleeve 55 is urged upward by a control spring 65 supported by a spring receiver 64 integrally formed on the outer periphery of the first piston 52.

On the other hand, on the outer periphery of the first piston 52, the first piston 52
an annular low pressure groove 67 communicating with the pump interior 30 via an internal low pressure hole 66 and a control hole 68 within the first piston 52;
An annular control groove 69 is provided which communicates with the control hydraulic chamber 59 via the annular control groove 69 .

An annular switching groove 70 is provided on the inner periphery of the sleeve 55 for communicating and switching between the low pressure groove 67 on the outer periphery of the first piston 52 and the control/l 169, and a high pressure groove 70 is provided on the outer periphery of the sleeve 55 in the axial direction. Pressure chamber 61 via 71
A radial high-pressure hole 72 communicating with is opened. Note that the switching groove 70 and the high pressure hole 72 are provided so as not to communicate with the control groove 69 of the first piston 52 at the same time. Also,
The sleeve 55 is connected to the storage chamber 51 by the control spring 65.
When the position is above in the figure, the first piston 52 control'
11! The I69 and the high pressure hole 72 of the sleeve 55 are in communication with each other.

Further, a second piston 75 similar to the first piston 52 is provided above in FIGS. 1 and 2, and the shaft 7
It is in rolling contact with the outer ring 4b by a roller 77 supported by the outer ring 4b. A spring 79 supported by a cap 78 screwed onto the housing 1 is disposed on the upper surface of the second piston 75, and the second piston 75 urges the guide ring 4 downward in FIG. There is. Note that the setting force of the spring 60 of the first piston 52 is the same as that of the second piston 75.
Since the setting force of the spring 79 is larger than the setting force of the spring 79, the guide ring 4 is normally positioned upward and has the maximum eccentricity.

Next, the operation of the pump will be explained based on the above configuration.

When the rotor 2 rotates clockwise in Fig. 2, the rotation center 0 of the rotor 2 and the center point 0 of the guide ring 4 are eccentric, so the plunger 3 performs reciprocating motion to suck in and discharge hydraulic oil. That will happen. In the suction stroke when the plunger 3 is in the left half of the 0 point, the working fluid is supplied from the suction port 12 to the pump chamber 23 through the suction hole 17, suction groove 15, and communication hole 20.
inhale. Next, in the discharge stroke in which the rotor 2 rotates and the piston moves to the right half of the zero point, the fluid in the pump chamber 23 is passed through the communication hole 20, the discharge groove 14, and the discharge hole 16 to the discharge port 11.
Discharge to. Here, the guide ring 4 can be moved vertically as shown in FIG. For example, if the guide ring 4 is moved downward in the figure, the distance between the center 0 point and the 0' point,
In other words, the displacement becomes smaller and the movement stroke of the plunger 3 becomes smaller, so the change in the volume of the pump chamber 23 becomes smaller, and the amount of fluid discharged from the discharge port 11 can be reduced. .

In this embodiment, in order to reduce the weight as much as possible when moving the guide ring 4 upward, the rollers 53,
The outer ring 4b of the 20th llama 7 and the kite ring 11 are in rolling contact. Further, the inner ring 4a and the outer ring 4b are also configured to make rolling contact via the copper balls 4C.

Furthermore, since the guide ring 4 is pushed to the right in FIG. 2 by the reaction force of the plunger 3 during the discharge stroke, the outer ring 4b does not simply move up and down in FIG. When moving upward, the outer ring 4b moves while rolling in a clockwise direction, and when moving downward, it rolls in an inverted clockwise direction.

Capacity control in the present invention will be explained.

If the rotation of the pump rotor 2 is slow, the pump chamber 23
Since the differential pressure ΔP generated across the variable throttle 29 by the oil discharged from the valve is small, the sleeve 55 is positioned above the storage chamber 51 by the control spring 65. At this time, the high pressure hole 72 of the sleeve 55 controls the first piston 52? Since it communicates with a69, the pressure of the pressure chamber 61, that is, the discharge pressure, is introduced into the control hydraulic chamber 59. Therefore, the first piston 52 moves against the guide ring 4 against the second piston 75.
is pressed upward in the figure to maximize the eccentricity e between the rotor 2 and the guide ring 4. At this time, the pump chamber 23 repeats maximum volume fluctuations and discharges the maximum amount of oil per -rotation.

When the rotational speed of the pump rotor 2 increases and the differential pressure ΔP across the variable throttle 29 increases and exceeds the set force of the control spring 65, the sleeve 55 is moved downward by the hydraulic pressure introduced into the pressure chamber 61. begins to move. Then, communication between the control groove 69 of the first piston 52 and the high pressure hole 72 of the sleeve 55 is cut off, and the control groove 69 of the first piston 52 is connected to the low pressure i67 of the first piston 52 via the switching groove 70 of the sleeve 55.
One communicates with the low pressure inside the pump 30. Then, the pressing force of the second piston 75, the horizontal force acting on the guide ring 4 (force that reduces the amount of eccentricity), and the restraint spring 6
The first piston 52 acts downward due to the urging force of
The eccentricity ie of the guide ring 4 becomes smaller, and the discharge amount per rotation is reduced.

When the first piston 52 moves downward, the sleeve 5
The high pressure hole 72 of the first piston 5 is connected to the control groove 69 of the first piston 52, and the pressure in the control hydraulic chamber 59 is upper bound.
An upward pushing force acts on 2. Therefore, in the end, the control groove 69 of the first piston 52 is located between the groove 70 and the high pressure hole 72 of the sleeve 5S, as shown in FIG. The relative position of the sleeve 55 becomes constant.At this time, the force acting on the sleeve 55 due to the differential pressure ΔP of the variable throttle 29 is 111
1 Balanced with iJI + spring 65.

As described above, the first piston 52 moves following the sleeve 55 so that the relative position of the force 1 piston 52 and the sleeve 55 is constant, and the eccentricity e of the guide ring 4 is
control. Therefore, the first piston 52
The eccentricity e of the guide ring 4 is controlled by the sleeve 55 which responds to the differential pressure ΔP of 9, and the discharge amount from the pump is controlled so that the differential pressure ΔP of the variable throttle 29 is constant.

As shown by the alpha line number in FIG. Control the amount so that it is constant.

Further, by adjusting the aperture area of the variable aperture 29, the discharge amount can be controlled from any rotational speed as shown in the β and γ rays in FIG. β-rays show the case where the aperture area of the variable aperture 29 is made small, and γ-rays show the case where the aperture area is made large.

Next, a second embodiment will be described based on FIGS. 4 to 8.

In this embodiment, a pressure control valve 1 is installed in the middle of a flow path 80 that communicates the downstream of the variable throttle 29 and the oil inlet 63 of the pilot chamber 62.
00 is set. The pressure control valve 100 uses the downstream pressure P2 of the variable throttle 29 as a pilot pressure to control the pilot chamber 6.
2 is switched to communicate with the downstream of the tank 28 or the variable throttle 29. When the pilot pressure is smaller than the setting force of the spring 101, the positive force control valve 100 closes the pilot chamber 6.
2 is communicated with the downstream of the variable throttle 29, and when the biloft pressure is large, the biloft chamber 62 and the tank 28 are communicated.

By adjusting the setting force of the spring 60 that urges the first piston 52 and the setting force of the spring 79 that urges the second piston 75, the guide ring 4 has the maximum eccentricity when the discharge pressure from the pump is zero. If the setting is made as shown in FIG. 5 and FIG. 6, the discharge port from the pump will have the characteristics shown in FIGS. Figure 5 shows
6, which shows the relationship between the discharge pressure and the discharge amount under a constant condition of the pump rotation speed N"°.

When the pressure downstream of the variable throttle 29 is small, the pressure control valve 1
00 is for guiding the downstream pressure of the variable throttle 29 to the pilot chamber 62 as shown in FIG. 4, and the discharge amount is controlled to be constant at the rotation speed N or higher, as in the first embodiment. However, when this pressure rises to a predetermined force P, the pilot chamber 62 is connected to the tank 28 by the pressure control valve 100, and when the pressure in the viroft chamber 62 decreases, the sleeve 55 has a pressure chamber 61, a pyro, and a variable pressure A differential pressure greater than or equal to 62 across the throttle 29 is applied. Then, the sleeve 55 moves downward, and the first piston 52 moves as described in the first embodiment.
The guide ring 4 also follows and moves downward, and the eccentricity of the guide ring 4 becomes smaller, and finally the eccentricity becomes almost zero. At this time, the discharge amount decreases, but the discharge pressure downstream of the variable throttle 29 is maintained.

Moreover, the spring 101 of the pressure control valve 100 in this case
When the setting force of the spring 1'01 is made smaller, the discharge pressure point P at which the discharge amount decreases moves to the lower pressure side, as shown by the dotted line a in Fig. 5, and conversely, when the setting force of the spring 1'01 is increased, the point P of the discharge pressure decreases as shown by the dotted line a. , the discharge pressure point moves to the high pressure side.

By preventing the discharge above a certain predetermined discharge pressure in this way, it is possible to prevent damage to the device to which hydraulic oil is supplied from the pump and overload of the drive device of this pump, and also to prevent the pump from overloading the drive device of the pump. Compared to the method of releasing the above to the tank using a relief valve or the like, power loss can be prevented.

Note that the guide ring 4 is connected to the spring 6 of the first piston 52.
By 0, the amount of eccentricity is adjusted by 7 to maximize the amount of eccentricity.

However, when the pump starts, the guide ring 4 receives a pushing force from the center 0 outward (1111) by each plunger 3 due to the pressure in the pump chamber 23, and when the pushing force of each plunger 3 is directed downward, the guide ring 4 The ring 4 is pressed in the direction to reduce the amount of eccentricity (downward in FIG. 4). Therefore, when the discharge pressure from the pump increases, the guide ring 4 overcomes the spring 60 of the first piston 52 and reduces the amount of eccentricity. Move to make it smaller.

Next, FIGS. 7 and 8 will be explained. Incidentally, FIG. 7 is taken on the plane (b) between the discharge pressure axis and the upper discharge axis in FIG. 8.

This is done by adjusting the spring 60 of the first piston 52 and the spring 79 of the second piston 75 so that when the pump discharge pressure is zero, the guide ring 4 is approximately 1/3 to 1/3 of the maximum eccentricity.
FIG. 3 is a diagram showing the characteristics when set to be /2. At this time, to explain with reference to FIG. 2, the control device 50
The first piston 52 and the sleeve 55 are in a positional relationship where the control groove 69 connects with the high pressure hole 72, and the control hydraulic chamber 5
A pump discharge pressure is introduced into 9. Furthermore, when the discharge pressure is extremely low, the differential pressure ΔP across the variable throttle 29 is small, so the sleeve 55 does not move, and the above-mentioned positional relationship is maintained, and the control device 50 controls the eccentricity of the guide ring 4. It is controlled to increase. Therefore, as shown in FIG. 7, when the discharge pressure is below P', the guide ring 4
increases the amount of eccentricity, and the amount of discharge increases.

When the discharge pressure of the pump rises to the discharge pressure P', the differential pressure ΔP across the variable throttle 29 becomes large, and the sleeve 55 is moved to the above-mentioned first position. It operates as described in the second embodiment to control the discharge amount.

In this way, by lowering the discharge amount when the discharge pressure is extremely low, that is, when the hydraulic system does not require the supply of hydraulic oil from the pump, it is possible to reduce the power consumption of the pump drive source during those times. can.

Incidentally, in the above embodiment, a variable displacement radial plunger pump was used as an example of the variable displacement pump.
The present invention is not limited thereto, and may be a variable volume Hoehn pump or a gerotor pump.

Furthermore, when the pump is driven, a force is applied to the guide ring 4 in the direction of reducing the amount of eccentricity as described above, so the second piston 75 and spring 79 are not necessarily necessary for controlling the amount of eccentricity, but the second piston 75 and the spring 79 are not necessarily required. Vibration of the guide ring 4 is prevented by the piston 75 and the like.

In addition, if part of the discharge pressure is introduced to the back surface of the second piston 75, vibration of the guide ring 75 can be effectively prevented.

(Effects of the Invention) As described above, the present invention provides a sleeve on the outer periphery of the piston that changes the amount of eccentricity of the guide ring of a variable displacement pump, and switches the control hydraulic chamber by sliding the sleeve.
Since the amount of eccentricity of the guide ring is controlled by pressing the piston, the pump and the control device can be integrated compactly, which is an excellent advantage.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. FIG. 4 is a diagram showing the relationship, and FIG. 4 is a diagram showing the second embodiment, and FIGS. 5 to 8 are characteristic diagrams in the second embodiment. DESCRIPTION OF SYMBOLS 1... Housing, 2... Rotor, 4... Guide ring, 29... Flow rate control valve (variable throttle), 52...
・Piston (first piston), 55...Sleeve, 6
0...Spring, 64...Spring holder.

Claims (1)

[Claims] In a variable displacement pump, the volume of the pump chamber is changed by changing the eccentricity of the guide ring with respect to the rotor. A spring that presses the guide ring in the direction of increasing eccentricity and a piston that is biased by the internal pressure of a control hydraulic chamber into which pump discharge pressure can be introduced, and a piston that is provided around the outer circumference of the piston to control the flow rate from the pump. a sleeve that slides and switches the control hydraulic chamber to pump discharge pressure or low pressure based on the differential pressure generated in the flow rate control valve to be throttled; A variable displacement pump characterized by having a spring that biases against the force.