JPS61125966A - Capacitiy change-over device for vane pump - Google Patents

Abstract

PURPOSE:To save wasteful energy consumption by allowing a part of delivery ports to be used permitting the remaining delivery ports to be by-passed to suction ports with no pressure loss when the number of revolution of a vane pump is high. CONSTITUTION:Operating fluid is supplied from both delivery ports OP1 and OP2 to a fluid pressure response device 57 when the number of revolution of a vane pump 10 is low. The delivery port OP1 is connected with the fluid pressure response device 57 when the number of revolution of the vane pump 10 is increased where the capacity of fluid delivered from the delivery port OP1 is found to exceed the stated one. However, the remaining port OP2 is connected with suction ports IP1 and IP2 by means of a capacity change-over valve 20 allowing its to be by-passed with no pressure loss. This permits only the operating fluid to be supplied to the fluid pressure response device 57 from the delivery port OP1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a capacity switching device for a vane pump that supplies working fluid to a power steering device or the like.

[Prior art]

Conventionally, this type of vane pump has two discharge ports OPI and OP of the vane pump 10, as shown in FIG. 4, for example.
2 through the first and second discharge passages 1.2 to a fluid pressure responsive device 57 such as a servo valve of a power steering device and a power cylinder.
and the suction port I via the flow control valve 40.
P1. A flow control valve 40 is connected to the flow rate control valve 40 via a control pipe 44 to control the flow rate to be supplied to the fluid pressure response device 57 downstream of the throttle 6 that is connected to the IP2 and provided after the confluence of the two ridge passages 1.2. are doing. That is, as shown in FIG. 5, while the pump rotation speed is small, the controlled flow rate characteristic Q to the fluid response device 57 matches the discharge flow rate characteristic P of the vane pump 10 itself and increases in proportion to the pump rotation speed, but the discharge The flow rate is the value q1
When the pump rotation speed n1 is exceeded, the spool 41 of the flow rate control valve 40 is moved against the spring 42 due to the pressure difference generated before and after the throttle 56 to open the port 43, and the excess discharge flow from the vane pump 10 is returned to the passage. The control flow rate characteristic Q is bypassed to the suction passage 3 to IPl and IF5 to maintain the control flow rate at a constant value q1.
has been established.

[Problem that the invention seeks to solve]

In the above-mentioned prior art, the amount of bypass is indicated by the region X between the two flow characteristics P and Q in FIG. This will result in wasted energy consumption. This wasted energy consumption increases as the pump rotation speed increases, so the discharge flow rate characteristic P
It is possible to reduce this by reducing the slope of This is not desirable because it will not work.

The present invention uses only some of the discharge ports when the rotational speed of the vane pump is high and therefore the discharge flow rate is larger than necessary, and the remaining discharge ports are bypassed to the suction port without pressure loss, thereby eliminating waste. It reduces energy consumption.

[Means for solving problems]

The present invention provides a pump housing 11 as shown in the accompanying drawings.
a plurality of cam curves CI integrally provided within and on the inner periphery;
A cam ring 13 having a cam surface C made of C2, a rotor 16 connected to a rotating shaft 18 housed within the cam ring 13 and pivotally supported by the pump housing 11, and a cam surface C
, a plurality of vanes 17 slidably fitted in the radial direction at equal intervals on the circumference of the rotor 16 to constitute a plurality of partitioned pump chambers between C2 and the rotor 16; There are a plurality of sets of suction ports IP1. This is a capacity switching device for a vane pump 10 having IP2 and discharge ports OPI and O'P2, and its features, as shown in the illustrated embodiment, include the following configuration. That is, a plurality of discharge ports OP1. Part of OP2 is the first OPI.
The remaining discharge port OP 2 is connected to a fluid pressure response device 57 via a discharge passage 50 , and the remaining discharge port OP 2 is connected to a capacity switching valve 20 via a second discharge passage 51 . , when the discharge flow rate from the discharge port OP1 is less than a predetermined amount, the fluid pressure response device 57 is activated, and when the discharge flow rate from the discharge port OP1 is greater than the predetermined amount, the suction port IP1. configured to selectively connect to IP2;
Furthermore, if the amount of working fluid supplied from the vane pump 10 to the fluid pressure response device 57 exceeds a predetermined value, a portion of the working fluid is transferred to the first discharge passage 50 through the suction port IPI.

A flow control valve 40 that bypasses during summer P2 is provided.

[Effect]

When the rotational speed of the vane pump 10 is low and therefore the discharge flow rate from some of the discharge ports OP1 is less than a predetermined amount, the discharge ports OP1 are connected to the fluid pressure response device 57 as shown in FIG. 1(a). At the same time, the remaining discharge port OP2 is also connected to the fluid pressure motor 57 by the capacity switching valve 20, and the working fluid from both discharge ports OP1 and OP2 is supplied to the fluid pressure response device 57. Therefore, in this state, the discharge flow rate characteristic of the vane pump 10, as shown by Pl in FIG. 3, is basically the same as the conventional discharge flow rate characteristic P (see FIG. 5). However, if the rotational speed of the vane pump 10 increases and the discharge flow rate from some of the discharge ports OP1 becomes larger than a predetermined amount, the discharge ports OP1 are connected to the fluid pressure response device 57, as shown in FIG. (However, the remaining discharge port) OP2 is connected to the suction port I by the capacity switching valve 20.
It is connected to PI and IP2 and bypassed without pressure loss, and only the working fluid from the discharge port OP1 is supplied to the fluid pressure response device 57, and the vane pump 10
As shown in FIG. 3, the discharge flow rate characteristic P2 has a smaller slope than the discharge flow rate characteristic P1. Therefore, the discharge flow rate characteristic of the vane pump 10 has a bent line shape as shown by PI-P3-P2 in FIG. If the discharge flow rate exceeds the value q1, it is bypassed by the flow rate control valve 40 and the controlled flow rate characteristic supplied to the fluid pressure response device 57 is the same as before.
becomes. This bypass amount is determined by two flow characteristics PL-P3-
This is indicated by regions Y1 and Y2 between P2 and Q, which are smaller than the conventional region X (see FIG. 5).

〔Effect of the invention〕

As described above, according to the present invention, wasted energy consumption due to bypass of the flow control valve 40 can be reduced, the driving torque of the revan pump 10 can be reduced, and the control flow rate characteristics supplied to the fluid pressure responsive device 57 can be reduced. can be maintained the same as before.

〔Example〕

In the embodiment shown in FIGS. 1 and 2, the structure of the vane pump 10 will be explained first. A pair of side plates 14 and 15 are opposed to a cylindrical hole ttb formed in the pump housing 11 and open at one end. The cam ring 13 is held between the two sides (14 and 15),
These three members 13°, 14.15 are positioned in the pump housing 11 by positioning pins 19, and the cylindrical hole 11
The spring 12 is caused by the end cover 12 fitted to b.
The end cover 12 is fixedly pressed into the cylindrical hole 11b by a stop ring. A rotary shaft 18 is coaxially supported in the pump housing 11 and coaxially with the cam ring 13, and a center portion of a rotor 16 located within the cam ring 13 and having a slightly narrower width than the rotor 16 is splined to the tip of the rotary shaft 18.

As shown in FIG. 1, the inner periphery of the cam ring 13 has cam curves C,1°1, C2 of the same shape with a phase difference of 180 degrees.
A cam surface C is formed, and ten vanes 17 that are in sliding contact with the cam surface C are able to slide in the radial direction of the rotor 1.
It is inserted into 6. Ten pump chambers are defined by vanes 17 between the cam surface C and the outer peripheral surface of the rotor 16, and the volume of each pump chamber changes as the rotor 16 rotates. Rotor 16 of side plate 14.15
Two pairs of suction ports IPI, IP2 are formed on the surface facing each other, corresponding to the pump chambers making an expansion stroke, and each suction port IP1. The IP2 is connected by an annular groove 11a formed on the inner circumference of the pump housing 11, and the side plate 14 has two independent discharge ports 1-OP1 and OP2 corresponding to the pump chambers that perform the compression stroke. It is formed. The structure of the vane pump 10 is basically the same as the conventional one.

As shown in FIG. 1 (al), the suction ports IPI and IP2 are connected to the annular groove 11a of the pump housing 11 and
It is also connected to a reservoir 55 via suction passages 53, 53a to suck working fluid, and a discharge port (OP1) is connected to a fluid pressure response device such as a servo valve of a power steering device and a power cylinder through a first discharge passage 50. 57, and the discharge port OP2 is connected to the capacity switching valve 20 via the second discharge passage 51. Inside the capacity switching valve 20, three chambers 23, 24° 25 are formed by a spool 21 that can move axially.
The first half 50a of the discharge passage is connected via the port 26, and the second half 50b of the first discharge passage is connected to the fluid pressure response device 57. The third chamber 25 is connected to the first chamber 23 via a flow rate sensing valve 30, which will be described later, and is provided with a spring 22 that biases the spool 21 toward the first chamber 23. The capacity switching valve 20 also has two ports 2.
7.28, the port 27 is connected to the discharge port OP2 via the second discharge passage 51, and the port 28 is connected to the suction passage 53.degree. 53a by the return passage 52. When the discharge flow rate from the discharge port OP1 is less than a predetermined amount, the spool 21 of the capacity switching valve 20 is moved to the first position as shown in FIG.
located on the chamber 23 side and communicating the port 27 with the first chamber 23;
The working fluid from the discharge boat OP2 is supplied to the fluid pressure response device 57 through the rear half 5ob of the first discharge passage 50 together with the working fluid from the discharge port OP1.

In addition, when the discharge flow rate from the discharge port OP 1 is larger than a predetermined amount, the spool 21 is located on the third chamber 25 side as shown in FIG. The working fluid from the discharge port oP2 is returned to the suction ports IPi and IP2 without pressure loss.

As shown in FIG. 1, the flow sensing valve 30 has three ports 33.
, 34, 35, and port 34 is selectively connected to port 33 and port 35 by a pivotable spool 31. Each bow) 33, 34, and 35 are connected to the first chamber 23, the third chamber 25, and the reservoir 55 of the capacity switching valve 20, respectively, via conduits. Further, a spring 32 is provided in the pressure chamber 36 on the left side of the spool 31 to bias the spool 31 toward the opposing pressure chamber 37.
is connected to the front half 5 of the first discharge passage 50 via the control pipe 38.
It communicates with the downstream side of the throttle 58 provided at 0a, and the pressure chamber 37
is communicated with the upstream side of the throttle 58 via the control line 39. When the rotation speed of the vane pump 10 is lower than n2 and the discharge flow rate from the discharge port OP1 is less than or equal to a predetermined amount (a value of 91 or more, for example, 61/m1n, which will be described later), the pressure difference before and after the throttle 58 is small, so the spool 31 As shown in FIG. 1 (al), the third chamber 25 of the capacity switching valve 20 is located on the pressure chamber 37 side.
is communicated with the first chamber 23, and when the rotational speed increases and exceeds n2, and the discharge flow rate from OPI (discharge bow) exceeds a predetermined amount, the spool 31 is moved to the position shown in FIG. As shown in (middle), the pressure chamber 36 resists the spring 22.
Move the third chamber 25 of the capacity switching valve 20 to the reservoir 5.
It connects to 5.

As shown in FIG. 1, a first discharge passage 50, a suction passage 53.
A flow control valve 40 is provided between the valves 53a and 53a. A spool 41 is provided inside the flow control valve 40 so as to be able to move axially, and the spool 41 is connected to the suction passage 5 via a return passage 54.
3.53a is normally biased by a spring 42 to close the port 43, and a chamber housing the spring 42 is provided in the rear half 50b of the first discharge passage via the control pipe 44. It communicates with the downstream side of the throttle 56. The amount of supply to the fluid pressure response device 57 is a predetermined value q
l (for example, 6 J/win), the flow control valve 40 is activated due to the pressure difference before and after the throttle 56, and the flow rate control valve 40 is activated.
is opened, and the excess discharge flow rate from the vane pump 10 is returned to the suction passage 53.53a via the return passage 54.

Next, the operation when the first embodiment is used to drive a fluid pressure responsive device of a power steering device consisting of a servo valve and a power cylinder will be described. The rotation speed of the vane pump 10 driven by the engine is lower than n2, and the discharge flow rate from the discharge port OP1 is a predetermined amount (for example, 61/+++
in) In the following case, as shown in FIG. The working fluid from the re-discharge ports OPI and OP2 located on the chamber 23 side is supplied to the fluid pressure response device 57 via the rear half 50b of the first discharge passage 50. In this state, the re-discharge ball)O
The discharge flow rate characteristics from PI and OP2 are as shown in Pl in FIG.
in), the excess discharge flow rate shown in region Y1 is bypassed by the flow control valve 40 to the suction passages 53, 53a via the return passage 54, and the control flow rate supplied to the fluid pressure response device 57 is the value q1. is maintained.

When the rotational speed of the vane pump 10 rises above n2 and the discharge flow rate from the discharge port OP1 exceeds a predetermined amount, the flow rate sensing valve 30 moves to the third position of the capacity switching valve 20 as shown in FIG.
The chamber 25 is communicated with the reservoir 55, and the spool 21 of the capacity switching valve 20 moves to the third chamber 25 side to transfer the working fluid from the discharge port OP2 to the suction ports IPI, IP without pressure loss.
2, only the working fluid from the discharge port opi is supplied to the fluid pressure response device 57. In this state, the discharge flow rate characteristics from the discharge port OP1 are as shown at P2 in FIG.
The controlled flow rate bypassed to the suction passage 53.53a and supplied to the hydraulic response device 57 is maintained at the value q1.

As described above, according to this embodiment, the discharge flow rate characteristic of the vane pump 10 is <PI-P3-22 as shown in FIG. 3, and the control flow rate characteristic Q of the working fluid supplied to the fluid pressure response device 57 is The characteristics are the same as in the conventional case, and the regions Y1 and Y2 in which bypass accompanied by energy loss due to the flow control valve 40 occurs are reduced compared to the conventional region X.

In each of the above embodiments, two
A set of suction ports IPI, IP2 and discharge ports OPI,
Although the case of the vane pump 10 having OP2 has been described, the present invention can also be implemented in a vane pump having a substantially triangular or substantially square cam surface and three or four sets of suction and discharge ports.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention, and FIG.
) is a diagram of the entire structure including the vane pump, showing a low-speed rotation state, 1st issue) is a diagram also showing a high-speed rotation state, and Fig. 2 is a diagram of the vane pump along line u-n in Fig. 1(a). 3 is a characteristic diagram of "pump rotation speed-flow rate", FIG. 4 is a structural diagram of a conventional example, and FIG. 5 is a characteristic diagram of "pump rotation speed-flow rate" of a conventional example. Explanation of symbols 10... Vane pump, 11... Pump housing, 13... Cam ring, 16... Rotor, 17...
・Vane, 18... Rotating shaft, 20... Capacity switching valve,
40...Flow rate control valve, 50...First discharge passage, 51
...Second discharge passage, 57...Fluid pressure response device, IP
I, [P2... Suction port, OPl, OF2... Discharge port, C... Cam surface, C1, C2... Cam curve.

Claims (1)

[Claims] A pump housing, a cam ring that is integrally provided within the pump housing and has a cam surface formed of a plurality of cam curves on the inner periphery, and a cam ring that is housed within the cam ring and is connected to a rotating shaft that is pivotally supported by the pump housing. a plurality of vanes slidably fitted in the rotor in a radial direction at equal intervals on the circumference to constitute a plurality of pump chambers partitioned between the cam surface and the rotor; In a vane pump having a plurality of sets of suction ports and discharge ports provided corresponding to the plurality of cam curves to suck or discharge working fluid into the pump chamber, some of the plurality of discharge ports are connected to a first discharge port. The remaining discharge ports are connected to the fluid pressure response device via a passage, and the remaining discharge ports are connected to a capacity switching valve via a second discharge passage, and the capacity switching valve is connected to the second discharge port.
The discharge passage is selectively connected to the fluid pressure response device when the discharge flow rate from some of the discharge ports is less than a predetermined amount, and to the suction port when the discharge flow rate from the same discharge port is higher than a predetermined amount. The first discharge passage is configured to have a flow rate configured to bypass a portion of the working fluid to the suction port when the amount of working fluid supplied from the vane pump to the fluid pressure response device exceeds a predetermined value. A vane pump capacity switching device characterized by being equipped with a control valve.