JPS5841289A - Vane pump - Google Patents

Abstract

PURPOSE:To reduce driving power for a vane pump by a method wherein negative pressure is introduced to act in grooves for vanes in order to force the vanes to be kept sucked to the retracted positions respectively while no pressurized fluid of pump delivery is necessitated. CONSTITUTION:When no power assist by pressurized fluid discharged out of the pump 5 is necessitated any longer because of reduction in wheel resistance to the ground after a rolling stock starts traveling at accelerated speed, actuation of a speed detector switch 24 switches a solenoid controlled valve 20 to connect the vacuum line 18 to the negative pressure source 19. In this way, since negative pressure acts from the side 14B of the groove for each vane, each vane 13 is sucked to that position so that rotation of the rotor 12 does not function as normal pumping action. Therefore, pump delivery becomes almost none, and the driving load of the pump 5 can remarkably be reduced accordingly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vane pump, and particularly to a vane pump that sets the pump discharge amount to zep discharge when pump discharge pressure oil is not required.

In general, most of the vane pumps used in automobile power steering systems are fixed displacement vane pumps, while variable displacement vane pumps are capable of saving pump drive energy and reducing oil temperature rise when pump discharge oil is not required. It's hardly used.

This is because the basic structure of the conventional variable displacement vane pump is to proportionally change the discharge amount by changing the eccentricity of the main K and cam ring. As a result, noise and pulsation are large, and the life of the bearing is short, so it is difficult to use it for a power steering system of an automobile due to its safety and quietness.

Therefore, the present invention follows the structure of a conventional fixed displacement vane pump, but makes it possible to control the discharge amount of the pump to zero when pump discharge oil is not required. The purpose is to

Therefore, in the present invention, a vacuum passage is formed that opens on the side surface of the vane groove of the pump housed inside the pump housing, and this passage is necessary in the middle of the passage connected to the negative pressure source such as the vacuum passage. A switching valve is provided to communicate or shut off communication depending on the situation, and when pump discharge pressure oil is not required, vacuum is applied to the vane groove to hold the vane in the retracted position.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows an example in which the present invention is applied to a vane pump used in a power steering system.

In other words, in the figure 1 is the handle, 2 is the input shaft, and 3 is the input shaft 2.
and a power cylinder screwed together via a pole screw assembly; 4 is a control valve that switches according to the rotation of the input shaft 2; 5 is a pump driven by the engine;
When the handle 1 is rotated, the piston 6 of the power cylinder 3 tries to move in the direction corresponding to the rotation via the input shaft 2, but in order to power-assist this movement with hydraulic pressure,
When the control valve 4 is switched from 200 rotations of the input shaft, oil from the reservoir 7 is pressurized by the pump 5, guided to one oil chamber of the power cylinder 3 via the control valve 4, and then to the other oil chamber. 8B oil is returned to reservoir 7.

In the power cylinder 3, a steering link that is connected to a steering wheel (not shown) is connected to a sector gear 10 that meshes with a rack 9 of a piston 6, and when the handle 1' is rotated in this way, the hydraulic pressure is assisted. This allows you to easily change the direction of the wheels while receiving the shock.

This embodiment is based on such a power steering system, and aims to improve steering stability and fuel efficiency by reducing the pump discharge amount to zero in the high speed range of the pump 5 described above. This is shown in Figure 2 below.

The pump 5 includes a housing 11 which houses a split-joint type rotor 12 to be described later, and a large number of vanes 13 are arranged radially around the outer circumference of the rotor 12.

The vanes 13 are slidably inserted into vane grooves 14 formed in the radial direction with respect to the rotor 12.
The inner circumferential surface of the cam ring 15 located on the outside of the theta 12 and Stretch out until they touch.

The cam ring 15 has vanes 13 per revolution of the rotor 12.
is expanded and contracted twice, changing the volume of the working chamber 16 defined by each vane 13, the inner periphery of the cam ring 15, and the outer periphery of the rotor 12, and repeating suction and discharge of hydraulic fluid.

The four-wheel drive 12 is driven by the pump shaft 17, and the pump shaft 1
7 shows the rotation from the engine crankshaft (not shown) as V.
[Transmitted] via the belt.

On the other hand, in order to stop the discharge action of the pump S in the vehicle high speed range, each vane groove 140[14B has an opening 18A].
A plurality of vacuum passages 18 are provided, and these vacuum passages 18 are selectively communicated with a negative pressure source (pump pump or engine vacuum) 19 through an electromagnetic switching valve 20.

The vacuum passage 18 is formed to penetrate the inside of the starter 12 in order to prevent internal leakage of hydraulic oil, and its opening 18A is slightly enlarged in the axial direction of the starter 12 on the upper side surface of the vane #114. While the proximal end 1g
B is inserted into the shaft hole 12AKj of the p-tor 12.

A pump shaft 17 is spline-coupled to the shaft hole 12λ of the pump shaft 17, and an annular passage 21AK formed on the outer circumference of the pump shaft 17
The base end portion 18B communicates with the internal passage 21B formed inside the base end portion 18B and the side plates 22 and B! 1i
The vacuum passage 18 is communicated with a negative pressure source 19 via a via 22c.

The above-mentioned electromagnetic switching valve 20 is interposed in the middle of the pipe 23.

This electromagnetic switching valve 20 is energized when the vehicle speed detection switch 24, which operates at a high speed or a predetermined high speed range, is turned on, and switches the pipe 23 into a communicating state so that the vacuum from the negative pressure source 19 acts on the vacuum passage 18. It is something.

Incidentally, the above-mentioned μ-ta 12 is made of a sintered alloy, and the fifth
As shown in the figure, the rotor 12 is divided into two in the direction orthogonal to the axial center, and the vacuum passage 18 described above is formed in the middle of the joint surfaces 26A and 26B of each of the divided rotors 25 and 25B. After being integrally formed in 12 sintering steps, they are four-joined in a sintering furnace.

In this way, the vacuum passage 18 inside the rotor 12 and the opening 18A of its vane groove 14 can be easily formed integrally inside the quadruple rotor 12 by simply forming the groove bottom type.

Next, the effect will be explained.

When the vehicle is running at low to medium speeds, the electromagnetic switching valve 20 installed in the passage system of the vacuum passage 18 is in the shutoff position.

Therefore, the impurity gourd does not act on the vane groove 14 of the rotor 12 of the pump 5.

Therefore, as shown in Fig. 83, the vanes 13 protrude in the radial direction until they come into contact with the cam ring 15 due to the rotating centrifugal force of the vane 12 and the discharge oil pressure guided by the base end 14 of the vane groove 140, and the normal pumping action is resumed. conduct.

As a result, the oil discharged from the pump 5 is supplied to the power cylinder 3 via the control valve 4 which is switched when the handle is operated, and a light 71-handle operation is realized with hydraulic power assist.

On the other hand, when the vehicle travels at high speed and the ground resistance of the wheels decreases, and the power assist by the pressure oil discharged from the pump 5 becomes unnecessary, the speed detection switch 24 is activated and the vacuum passage 18 is connected to the negative pressure source 19 as described above. The electromagnetic switching valve 20 is switched to establish communication.

As a result, the backing mechanism (
Negative pressure) acts to attract the vane 13 to that position.The vane 13 is mechanically compressed when passing through the short diameter part of the cam ring 15, so the pressure is reduced by the pressing force and centrifugal force at the base end of the vane. When the vane 13 is also subjected to strong adsorption action,
is held apart from the inner periphery of the cam ring 15 as shown in FIG.

In this case, since the vacuum passage 18 is formed inside the rotor 12, internal leakage of hydraulic oil due to negative pressure inside the pump 5 can be prevented, so that the adsorption of the vane 13 is high.

Therefore, in this state, the normal pumping action cannot be performed even if the -me 12 rotates, and the pump discharge amount becomes almost zero, and the load driving the pump 5 is also significantly reduced. .

On the other hand, if the steering wheel is operated at this time, the control valve 4 is switched, but since no pressure oil is supplied, the operation of the power cylinder 3 is not power assisted by hydraulic pressure and becomes manual steering.

That is, the piston 6 of the power cylinder 3, which is screwed into the input shaft 2, moves back and forth every 20 revolutions of the input shaft to drive the steering link.

However, in such high-speed ranges, the power required to change the direction of the wheels is small, so there is no particular burden on the driver who operates the steering wheel 1, and rather, it is possible to avoid turning the steering wheel 1 too much. This makes it possible to improve stability.

On the other hand, in this way [, except when power assist is required, the vane 13 of the vane pump 5 is contracted to generate a zero discharge of 11 tl.
When j, the driving force of the pump is reduced, and this can be used to determine whether the fuel efficiency of the vehicle is improved.

In addition, since the pump 5 normally has zero discharge in the high-speed range where the discharge amount increases, the 74-cone valve is not required, simplifying the structure and lowering the thrust. There is no temperature rise, preventing deterioration of the hydraulic oil and improving durability.

Although this embodiment shows an example in which the present invention is applied to a vane pump for a power steering system, it goes without saying that the pump of the present invention can be applied to other devices as a variable displacement vane pump.

As explained above, according to this invention, Vanhong:#
) A vacuum passage is formed that opens on the side surface of the vane groove of the element, and a switching valve is provided in the passage that connects this vacuum passage to a negative pressure source to communicate or shut off the passage as necessary, and the pump discharge When pressure oil is not needed, a vacuum is applied to the vane groove to force the vane to adsorb and hold it in the retracted position, resulting in a major change in the structure of the constant displacement vane pump, which is quiet and durable. Add
In addition, when the pump discharges no pressure oil, it can be reduced to zero discharge, and the effect of reducing the pump driving force can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a power steering system in which the pump of the present invention is used, Fig. 2 is a sectional view of the pump, Figs. 3 and 4 are sectional views of the pump showing its operating state, and Fig. 5 is a sectional view of the pump. FIG. 2 is an explanatory diagram showing a method of manufacturing Shi-Yu. 11.-Pump housing, 12-t! -ta, 14...
・Vane groove, 14 B-・Side surface, 15-Cam ring, 1
3- Vane, 5... Vane pump, 18- Vacuum passage, 19- Negative pressure source, 23- Pipe, 20- Solenoid switching valve, 24- Speed detection switch. Patent applicant Kayaba Kogyo Co., Ltd. Figure 3 Figure 4 Figure 5 Figure 5B

Claims (1)

[Claims] 1. Vane grooves are formed radially in the rotor housed inside the pong housing, and the vane grooves extend so as to be in contact with the inner circumferential surface of the cam ring located on the outside of the cam ring. In a vane pump in which an ejecting vane is slidably inserted, a vacuum passage is formed that opens on the @ side of the vane groove of the rotor, and the passage is communicated in the middle of the passage connected to a negative pressure source such as the vacuum passage, A vane pump characterized by being able to absorb and hold by switching to shut off. 2. The above-mentioned cable is made of sintered alloy and is divided into two in the direction orthogonal to the axis of the rotor, each of which is divided into two parts with a vacuum passage in the shape of a split on the joint surface of the rotor when the rotor is sintered and formed. The vane pump according to claim 1, which is formed integrally and then raw-joined in a sintering furnace.