JPH0356457Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention is a power steering device that increases the steering force applied to the steering wheel and transmits it to the wheels using pressure fluid discharged by a pump driven by a power source. (hereinafter referred to as the PS device), to prevent the occurrence of abnormal noise, especially when the temperature of the operating oil for the PS device is low, such as when starting the engine.
Regarding hydraulic pumps for PS equipment.

[Conventional technology]

FIG. 7 shows a conventional hydraulic pump 1 disclosed in Japanese Unexamined Patent Publication No. 56-146472, and the configuration thereof will be explained below.

Reference numeral 2 designates a pump housing. A valve housing hole 3 is passed through the pump housing 2, and a union 4 is screwed into one end of the valve housing hole 3, and a stopper 5 is fitted into the other end. The union 4 has a substantially cylindrical shape, one end of which is inserted into the valve housing hole 3, and a pressurized fluid outlet 6 connected to a gearbox (not shown) opened at the other end.

The valve storage hole 3 has a supply passage 8 and a bypass passage 1.
0 are opened spaced apart from each other in the axial direction, and the supply passage 8 and the bypass passage 10 communicate with a discharge chamber and a suction chamber (both not shown) of the oil pump, respectively. The supply passage 8 is constantly communicated with the valve storage hole 3 through a restriction passage 11 formed in the union 4. The restriction passage 11 is configured such that when the pump discharge amount supplied to the supply passage 8 increases, a pressure difference is generated between the upstream side and the downstream side, that is, between the supply passage 8 and the valve housing hole 3 due to the flow passage resistance. It's getting old. The bypass passage 10 includes a suction port 12 for sucking oil from a reserve tank (not shown) and sending it to the suction chamber of the oil pump.
is formed with an opening.

Further, in the valve storage hole 3, a flow rate adjustment spool valve 1 is provided in order to close the communication path between the supply path 8 and the bypass path 10 and to adjust the opening degree of the communication path.
3 is slidably inserted, and a first valve chamber 15 and a second valve chamber 16 are formed on both sides of this spool valve 13. The second valve chamber 16 is provided with a compression spring 18 that presses the spool valve 13 toward the first valve chamber 15. The elastic force of the compression spring 18 normally pushes the spool valve 13 toward one end of the union 4. The supply passage 8 is held in a position where it abuts against the supply passage 8 and opens into the first valve chamber 15.
The communication between the bypass passage 10 and the bypass passage 10 is cut off.

A throttle member 20 is fitted into the union 4 in proximity to the outlet 6, and the center of the throttle member 20 communicates with the first valve chamber 15 and the outlet 6 via a fluid passage 24, which will be described later. A throttle passage 21 is formed. The union 4 also includes a control spool 22.
is slidably inserted into the control spool 22, and a fluid passage 24 that communicates the first valve chamber 15 and the throttle passage 21 passes through the control spool 22. At one end of the control spool 22, there is a control shaft portion 2 that controls opening and closing of the throttle passage 21.
5 is provided protrudingly. A compression spring 26 is inserted between the control spool 22 and the throttle member 20 in a resilient state, and the resilient force of the compression spring 26 causes the control spool 22 to move against the stepped portion 28 formed in the union 4. The control shaft portion 25 of the control spool 22 is thus spaced apart from the throttle member 20 and opens the throttle passage 21.

When the above-mentioned hydraulic pump 1 is rotated by an engine, working oil in a suction chamber of the oil pump is sucked into the pump chamber, and pressure oil is discharged into a discharge chamber. The pressure oil discharged into the discharge chamber is
From the control passage 11 through the supply passage 8 to the valve storage hole 3
The fluid is supplied to the first valve chamber 15 of the first valve chamber 15, and is sent from the first valve chamber 15 through the fluid passage 24 and the throttle passage 21 to the gearbox (not shown).

While the pump rotation speed is low, the pump discharge flow rate is also small, so the spool valve 13 is connected to the bypass passage 1.
0 is closed, and the entire pump discharge flow rate flows through the throttle passage 2.
1 to the gearbox, but as the pump rotation speed increases, the discharge flow rate also increases.
The spool valve 13 is slid to open the bypass passage 10 so as to keep the pressure difference before and after the throttle passage 21 constant, and excess oil flows from the bypass passage 10 into the suction chamber of the oil pump.

[Problem that the invention attempts to solve]

In such a pump for a PS device, when the temperature of the working oil decreases and the viscosity of the working oil is high, the bypass passage 10 is removed from the suction port 12.
It is difficult for working oil to enter from the reserve tank, and the excess oil that has flowed into the bypass passage 10 creates a negative pressure in the bypass passage 10 near the suction port 12. This causes a phenomenon in which the molten air contained in the hydraulic oil for the PS device comes out in the form of bubbles, so-called cavitation. When this working oil containing air bubbles is sucked into the oil pump, the air bubbles are compressed and locally become extremely high pressure, which hits the flow path and generates noise and vibration, which is a problem. It was hot. Such abnormal noises cause discomfort to the driver and passengers.
The ride wasn't very comfortable either.

This invention prevents abnormal noise by preventing cavitation bubbles from forming near the suction port of the bypass passage when the temperature of the working oil is low, such as when starting the engine.
The purpose of the present invention is to provide a hydraulic pump for PS equipment.

[Means for solving problems]

To achieve this objective, the hydraulic pump of the present invention is provided with a communication passage that communicates the discharge side and suction side of the oil pump, and a switching valve that is opened only when the engine is started is disposed in the communication passage. be.

[Effect]

According to the above configuration, when the engine is started, the switching valve is opened, and the working oil for the PS device is sent from the supply passage to the suction port or from the supply passage to the bypass passage, and the pressure in the bypass passage increases, so that the switching valve is not activated. Dissolved air in the oil does not become bubbles, so no abnormal noise is generated due to cavitation.

〔Example〕

Hereinafter, embodiments of the present invention will be described based on the drawings. Figures 1 and 2 show the first embodiment of the present invention. In the figures, the same parts as those shown in Figure 7 are given the same reference numerals, and their explanation will be omitted. .

The hydraulic pump 31 according to the present invention includes a switching valve 32.
is disposed at an intermediate portion of a communication passage 33 that communicates the supply passage 8 and the suction port 12 opened to the bypass passage 10, and is configured to cut off communication of the communication passage 33. The switching valve 32 is connected to the timer 34 by wiring 35.
The timer 34 is connected to the wiring 36.
is connected to the ignition 38 by.

Next, the operation of the first embodiment of the present invention will be explained. When starting the engine, ignition 3
8 turns ON, the timer 34 operates, the switching valve 32 opens, and the operating oil for the PS device is sent from the supply passage 8 through the communication passage 33 to the suction port 12 and flows into the bypass passage 10. Also, due to the atomizing effect at this time, the working oil from the reservoir tank is transferred from the suction port 12 to the bypass passage 1.
Since the air is sucked out to zero and the pressure in the bypass passage near the suction port 12 increases, the dissolved air in the operating oil for the PS device does not become bubbles, and therefore cavitation does not occur.

Next, when a predetermined period of time has passed since the ignition 38 was turned on, the timer 34 stops (timer 34
(the operating time is several seconds), the switching valve 32 closes and the communication path 33 is cut off. At this point, the temperature of the working oil is high and the viscosity is low, so the flow from the suction port 12 to the bypass passage 1
0 from the reservoir tank smoothly flows into the port 12, and the vicinity of the suction port 12 does not become negative pressure.

Figures 3 and 4 show a second embodiment of the present invention, and in these figures, the same parts as those shown in Figure 7 are given the same reference numerals and their explanation will be omitted. .

The switching valve 32 connects the supply passage 8 and the bypass passage 10.
The first valve chamber 15 is arranged in a communication passage 33 that communicates with the first valve chamber 15, which is an example of a valve chamber, and the communication passage 33 is disconnected from the communication passage 33.

Next, the operation of the second embodiment of the present invention will be explained.

When starting the engine, the ignition 38
When turned ON, the timer 34 operates and the switching valve 3
2 opens, and the working oil flows from the supply passage 8 through the first valve chamber 15 and through the communication passage 33 to the bypass passage 10.
flows into. Also, due to the atomizing effect at this time, the working oil from the reservoir tank is sucked out from the suction port 12 into the bypass passage 10, and the pressure in the bypass passage 12 increases, so that the dissolved air in the working oil for the PS device becomes bubbles. Therefore, cavitation does not occur.

5 and 6 show a third embodiment of the present invention, in which a switching valve 32 is disposed in a communication passage 33 that directly communicates the supply passage 8 and the bypass passage 10, and its operation is the same as the second embodiment,
The explanation will be omitted.

[Effect of idea]

As described above, according to the present invention, when the temperature of the working oil for the PS device is low, such as when starting the engine, cavitation bubbles generated near the intake port of the bypass passage are removed by the operation of the switching valve. This does not occur because the pressure in the area becomes high.
Therefore, no abnormal noise is generated, the driver and fellow passengers are not made to feel uncomfortable, and the riding comfort is improved.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of a hydraulic pump according to a first embodiment of the present invention, Fig. 2 is an enlarged longitudinal cross-sectional view of the switching valve related to Fig. 1, and Fig. 3 is a second embodiment of the present invention. FIG. 4 is an enlarged vertical cross-sectional view of the switching valve related to FIG. 3; FIG. 5 is a vertical cross-sectional view of the hydraulic pump according to the third embodiment of the present invention; FIG.
The figure is an enlarged vertical sectional view of the switching valve related to Fig. 5,
FIG. 7 is a longitudinal sectional view of a conventional hydraulic pump. 8... Supply passage, 10... Bypass passage, 12
... Suction port, 15 ... No. 1, which is an example of a valve chamber
Valve chamber, 21... Throttle passage, 31... Hydraulic pump for power steering device, 32... Switching valve, 33... Communication passage.

Claims (1)

[Claims for Utility Model Registration] 1. Pressurized oil in a valve chamber is sent to a gearbox via a throttle passage from a supply passage communicating with the discharge side of the oil pump, and surplus flow is sent to the suction side of the oil pump via a bypass passage. In the hydraulic pump for a power steering device, the hydraulic pump for a power steering device is provided with a suction port configured to suck oil from a reserve tank into the bypass passage and send it to the suction side of the oil pump. 1. A hydraulic pump for a power steering device, characterized in that a communication passage is provided that communicates the intake side with the intake side, and a switching valve that is opened only when the engine is started is disposed in the communication passage. 2. The hydraulic pump for a power steering device according to claim 1, wherein the communication path is a flow path that communicates the supply path and the suction port.