JP3085046B2 - Reservoir tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reservoir tank,
In particular, the present invention relates to a reservoir tank that prevents cavitation by increasing internal pressure, such as a reservoir tank used in a power steering device of a vehicle.

[0002]

2. Description of the Related Art For example, in a vehicle power steering apparatus, a pressure fluid generating source (for example, a hydraulic pump) and control means (for example, a control valve) for controlling the flow of a pressure fluid (pressure oil) from the hydraulic pump are provided. A reservoir tank connecting the hydraulic pump and the control valve is provided therebetween. In such a power steering device, when the steering wheel is steered,
That is, the internal pressure of the reservoir tank is increased to be higher than the atmospheric pressure so that cavitation does not occur when the power steering device is operated, and the back pressure in the flow passage is increased.

A power steering apparatus which suppresses the occurrence of cavitation during steering by increasing the internal pressure of the reservoir tank during steering of the steering wheel as described above is disclosed in, for example, Japanese Patent Application Laid-Open No. 58-202164. Are conventionally known.

In the conventional apparatus disclosed in the above publication, a detecting means for detecting the steering of the steering wheel, and an air pump connected to the reservoir tank and operated when the detecting means detects the steering of the steering wheel. And the like. When the steering of the steering wheel is detected by the detecting means, the internal pressure controlling means operates to introduce the pressurized air into the reservoir tank.

[0005] Then, by increasing the internal pressure in the reservoir tank by the pressurized air introduced into the reservoir tank, the back pressure in the flow path is increased to suppress the occurrence of cavitation.

[0006]

However, in order to suppress the cavitation by pressurizing the inside of the reservoir tank as in the above-mentioned conventional apparatus, the above-described detection means is provided, and the above-described internal pressure control means is provided to provide the reservoir. The connection to the tank has a problem that the structure of the apparatus is complicated.

The present invention has been made in view of the above points, and has an inlet for injecting a pressurized gas into a reservoir tank, and allows the inflow of the pressurized gas from the inlet into the inlet. Another object of the present invention is to provide a reservoir tank that can pressurize the inside of the reservoir tank with a simple structure by providing a valve that restricts outflow.

[0008]

According to the present invention, there is provided a reservoir tank provided between a pressure fluid generation source and a control means for controlling the flow of the pressure fluid from the pressure fluid generation source and connecting these components. An inlet for injecting pressurized gas,
A valve disposed at the inlet, for permitting inflow of the pressurized expectation from the inlet and for limiting outflow ;
The state changes according to the pressure of the gas enclosed inside.
And an internal pressure notifying means.

[0009]

The internal pressure of the reservoir tank is increased by injecting the pressurized gas into the reservoir tank through a valve disposed at the inlet and allowing the pressurized gas to be injected into the reservoir tank. In this case, the inside of the reservoir tank
Whether or not the pressure has been increased to the specified pressure depends on the state of the internal pressure notification means.
Recognized by state change. Then, the pressurized gas injected into the reservoir tank is restricted from flowing out of the reservoir tank by the valve, and the pressurized state in the reservoir tank is maintained.

Therefore, without providing an air pump or the like,
It is possible to pressurize the inside of the reservoir tank with a simple structure.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a power steering device for a vehicle will be described below. FIG. 1 is a sectional view of a reservoir tank according to the present invention, and FIG. 2 is a perspective view showing an example of a power steering device according to an embodiment of the present invention.

In FIG. 2, reference numeral 1 denotes a power steering apparatus according to the present embodiment as a whole. In the figure, reference numeral 2 denotes a steering wheel connected to a steering column 3, and reference numeral 4 denotes a power steering pump corresponding to the above-described pressure fluid generating source for generating pressure oil. The power steering pump 4 is configured such that a belt (not shown) is wound around a pulley 5 and is driven to rotate by an engine (not shown).

In FIG. 2, reference numeral 6 denotes a gear box corresponding to the control means. The gear box 6 is supplied with pressure oil from the power steering pump 4 via a high-pressure pipe 7. . Also, gear box 6
Is provided with a control valve (not shown) for controlling the flow of pressure oil in response to the movement of the steering wheel 2.

In FIG. 2, reference numeral 8 denotes a power cylinder, in which a piston (not shown) defining two hydraulic chambers (not shown) is incorporated, and high-pressure oil controlled by a control valve of the gear box 6 is provided. It is configured to be introduced into one of the hydraulic chambers through one of the pipes 9 and 10. A piston rod 11 protrudes from both ends of the power cylinder 8, and the piston rod 11 protrudes from both ends.
Are connected to steering wheels (not shown).

In FIG. 2, reference numeral 12 denotes an oil cooler 12a on the way.
Is a low-pressure pipe in which the gear box 6 is mounted.
The return oil is returned to the reservoir tank 13. In the figure, reference numeral 14 denotes a low-pressure pipe, and the power steering pump 4 sucks hydraulic oil in the reservoir tank 13 through the low-pressure pipe 14.

The recirculated hydraulic oil 15 is temporarily stored in the reservoir tank 13 as shown in FIG.

Here, the structure of the reservoir tank 13 will be described in detail. As shown in FIG. 1, a reservoir inlet hole 21 to which the low-pressure pipe 12 is connected and a reservoir outlet hole 22 to which the low-pressure pipe 14 is connected are formed in the reservoir tank 13. A filter 23 for removing foreign matter in the hydraulic oil 15 flowing from the inlet hole 21 is provided.

An inlet 31 is provided on the upper surface of the reservoir tank 13. The inlet 31 has a substantially cylindrical projecting portion 32 projecting inward of the reservoir tank 13 as shown in FIG. , Openings 3 respectively formed in the upper and lower parts
3 and 34. Further, a seal 41 corresponding to the above-described valve is provided in the protruding portion 32 of the injection port 31.

The seal 41 is made of an elastic material, and is normally closed so as to keep the inside of the reservoir tank 13 airtight as shown in FIG. 3, but it is closed by an injection nozzle 42 as shown in FIG. When the pressurized gas, for example, nitrogen gas of about 0.2 to 0.4 MPa is injected into the tank 13 to pressurize the reservoir tank 13 to a predetermined pressure or when oil is injected, the injection nozzle 42 is used. Is elastically deformed so that it can be inserted into the reservoir tank 13 through the openings 33 and 34 and the seal 41.

Accordingly, the seal 41 has a function of permitting the nitrogen gas to be injected into the reservoir tank 13 from the injection port and a function of restricting the outflow of the nitrogen gas injected into the reservoir tank 13. .

A gas pressure checker mounting port 51 is formed on the upper surface of the reservoir tank 13 so as to protrude outward from the reservoir tank 13, and a gas pressure checker 61 is formed at an upper end of the gas pressure checker mounting port 51. Is attached.

The gas pressure checker 61 is made of a balloon-like elastic body, and is for checking the gas pressure sealed in the reservoir tank 13. The pressure in the reservoir tank 13 is higher than the atmospheric pressure. For example, when the pressure is about 2 to 3 atm, the state is expanded as shown in FIG. 5A, and when the pressure in the reservoir tank 13 is the atmospheric pressure or the negative pressure, 5
As shown in (b), it is in a withered state.

Accordingly, the user can know the decrease in the gas pressure in the reservoir tank 13 by changing the state of the gas pressure checker 61. When the gas pressure checker 61 detects a decrease in the gas pressure in the reservoir tank 13, the injection nozzle 42 is inserted into the reservoir tank 13 through the injection port 31 and the seal 41 to discharge the nitrogen gas. The inside of the reservoir tank 13 can be pressurized to a predetermined pressure by injection.

Next, the operation of the above embodiment will be described.

First, after assembling the power steering parts on a vehicle production line or the like, the injection nozzle 42 is connected to the injection port 3.
1 is inserted into the reservoir tank 13 through the openings 33 and 34 and the seal 41 formed therein, and nitrogen gas pressurized to a predetermined pressure is injected into the reservoir tank 13 so that the reservoir tank 13 The inside is pressurized to a predetermined pressure. In this case, whether or not the pressure in the reservoir tank 13 has been increased to a predetermined pressure is recognized by a change in the state of the gas pressure checker 61. Further, outflow of the nitrogen gas injected into the reservoir tank 13 to the outside of the reservoir tank 13 is restricted by the seal 41. Therefore, the pressurized state in the reservoir tank 13 is maintained. Further, in the production line, it is possible to simplify the injection work by providing a regulator in the gas injection device.

In the power steering apparatus 1 in which the reservoir tank 13 is pressurized as described above, when the steering wheel 2 is steered from the neutral position, the gear box 6 responds and the power steering pump 4 generates the power. The pressure oil thus introduced is introduced into one hydraulic chamber of the power cylinder 8, and the oil in the other hydraulic chamber of the power cylinder 8 is discharged to the reservoir tank 13. Thereby, the power cylinder 8
The inner piston is pressed to generate a steering assist force to steer a steering wheel (not shown).

In the power steering apparatus 1 operating as described above and pressurizing the inside of the reservoir tank 13, a narrow throttle portion having a narrow flow path is formed in the flow path of the gear box 6 or the like. Also, since the back pressure in the channel is high, the occurrence of cavitation due to the pressure drop is suppressed, and as a result, the generation of abnormal noise and the generation of vibration are suppressed.

When the pressure in the reservoir tank 13 becomes atmospheric pressure or negative pressure, a change in the state of the gas pressure checker 61 causes a decrease in the gas pressure in the reservoir tank 13. Pressurizes the reservoir tank 13 to a predetermined pressure by inserting the injection nozzle 42 into the reservoir tank 13 through the injection port 31 and the seal 41 and injecting nitrogen gas pressurized to a predetermined pressure. Thus, the occurrence of cavitation can be suppressed.

Here, the principle of suppressing cavitation by filling nitrogen gas in the reservoir tank 13 and pressurizing the reservoir tank 13 will be briefly described.

As shown in FIGS. 6A and 6B, when the pressure ratio P ₂ / P ₁ before and after the orifice 65, the flow rate Q of the oil flowing through the orifice 65, the area of the orifice 65, and the like are changed, the cavitation is reduced. It is generally known that a generated / non-generated line becomes like a curve A shown in FIG. In FIG. 6A, the arrow B indicates the flow direction of the oil, and P ₁ and P ₂ are the pressure values before and after the orifice 65, respectively.

Then, from the state D in the cavitation generation region C because P ₂ is atmospheric pressure, the gas pressure is increased to P.
_By applying the pressure to ₂ , the pressure ratio P ₂ / P ₁ before and after the orifice 65 is increased, whereby the state F in the cavitation-free area E can be obtained. Therefore, according to this principle, cavitation can be suppressed by pressurizing the reservoir tank 13.

Actually, when the wheels stick-slip on the low friction road and acceleration (force) several tens of times as normal enters the gear box 6 as a reverse input, the pressure fluctuation in the low pressure pipe 12 and the oil cooler 12a The test for measuring the magnitude of the vibration was performed by increasing the gas pressure in the reservoir tank 13 from the atmospheric pressure to +0.
When the test was carried out while changing the pressure up to 4 MPa, the results shown in FIGS. 7A and 7B were obtained. FIG. 7 (a)
7, the solid line A and the dashed line B show the measurement result of the pressure fluctuation near the inlet of the reservoir tank 13 of the low-pressure pipe 12 and the measurement result of the pressure fluctuation near the outlet of the gear box 6 of the low-pressure pipe 12, respectively. The solid line C indicates the measurement result of the magnitude of the vibration of the oil cooler 12a.

As is clear from the measurement test results shown in FIGS. 7A and 7B, the pressure fluctuation of the low-pressure pipe 12 and the pressure fluctuation of the low-pressure pipe 12 can be obtained only by applying the gas pressure of 0.2 MPa (2 atm) into the reservoir tank 13. The vibrations of the oil coolers 12a are greatly suppressed. Therefore, pressure fluctuation and vibration of the power steering device 1 are greatly reduced.

According to the above-described embodiment, the inlet 31 for injecting nitrogen gas, which is a pressurized gas, into the reservoir tank 13, and the flow of nitrogen gas from the inlet 31 into the inlet 31. Seal 4 that allows flow and restricts outflow
1 can easily pressurize the inside of the reservoir tank 13 by simply providing the internal pressure control means, such as an air pump, to pressurize the inside of the reservoir tank 13 with a simple structure. The pressure in the reservoir tank can be increased, and the occurrence of cavitation can be significantly suppressed.

Also, since the occurrence of cavitation can be greatly suppressed, it is not necessary to individually take measures against pressure fluctuation, vibration, sound, etc. caused by the occurrence of cavitation as in the conventional case. Cost and weight can be reduced.

Further, since the reservoir tank 13 is of a closed type, oil in the reservoir tank 13 does not overflow from the reservoir tank 13 due to vibration when the engine is rotated at a high speed.

In the present invention, the pressurized gas is not limited to nitrogen gas as in the above-described embodiment.

Further, in the present invention, the reservoir tank 1
The valve which permits the flow of the pressurized gas into the tank 3 and restricts the flow of the pressurized gas from the reservoir tank 13 is not limited to the seal 41 made of an elastic body as in the above-described embodiment. What is necessary is just to have the function which permits the inflow of the pressurized gas from the inside of the tank 13, and restricts the outflow of the pressurized gas from the inside of the reservoir tank 13.

[0039]

According to the present invention, an inlet for injecting a pressurized gas, and an inlet for the pressurized gas from the inlet and restricting the outflow from the inlet are provided only in the reservoir tank. Can be easily pressurized, so that the inside of the reservoir tank can be pressurized with a simple structure and cavitation can be suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a reservoir tank according to the present invention.

FIG. 2 is a perspective view showing an example of a power steering apparatus according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a state of a seal and the like in a normal state.

FIG. 4 is a sectional view showing a state of a seal and the like at the time of gas injection.

FIG. 5 is a sectional view showing a gas pressure checker and the like.

FIG. 6 is a diagram for explaining the principle of suppressing cavitation.

FIG. 7 is a characteristic diagram for explaining the effect of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power steering device 2 Steering wheel 3 Steering column 4 Power steering pump 5 Pulley 6 Gear box 7 High pressure pipe 8 Power cylinder 11 Piston rod 12, 14 Low pressure pipe 13 Reservoir tank 21 Reservoir inlet hole 22 Reservoir outlet hole 23 Filter 31 Inlet 41 Seal 42 Injection nozzle 51 Gas pressure checker attachment port 61 Gas pressure checker

Claims (1)

(57) [Claims] A reservoir for injecting a pressurized gas is provided in a reservoir tank provided between and connected to a pressure fluid generation source and control means for controlling a flow of the pressure fluid from the pressure fluid generation source. An inlet, a valve disposed at the inlet, for permitting the inflow of the pressurized expectation from the inlet and restricting the outflow ; and an elastic body, which responds to the pressure of the gas sealed therein.
And a means for notifying an internal pressure that changes state in a short time .