JPS6325270Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for controlling the flow rate of working fluid from a pump to a fluid operating device such as a power steering system.

In the case of fluid-operated devices such as power steering systems for automobiles, in which working fluid is supplied by a pump driven by the automobile's engine, the engine speed varies from a minimum of approximately 500 revolutions per minute to a high speed, depending on the driving condition of the automobile. The engine rotates over a wide range of over 6,000 revolutions per minute while driving, and the pump driven by the engine is also driven over a similarly wide range of rotation speeds, so the pump's discharge flow rate varies depending on the driving conditions of the vehicle. If the design is designed to ensure the required flow rate during low-speed rotation, an extremely large amount of surplus fluid will be discharged during high-speed rotation. Therefore, a flow control valve is used that ensures a substantially constant amount of pressurized fluid necessary for the operation of the fluid actuator, and bypasses excess fluid to a pump suction chamber or reservoir to adjust the amount of fluid delivered to the actuator.

However, fluid-operated devices for automobiles include
When the engine speed is high, the pressure fluid may not be used as effectively as when the engine is rotating at low speed. In other words, in the case of a power steering system, when the engine speed is high, the vehicle speed is proportionally high, and the steering angle is rarely large compared to when driving at low speeds, and the power steering system operates under almost no load conditions. The pressure fluid is also discharged into the suction chamber or reservoir of the pump with little effective use.

As a result, the pump rotation speed increases to a certain extent,
Various attempts have been made to reduce the flow rate delivered to the fluid operating device when the pump discharge flow rate increases, thereby improving the stability of the fluid operating device and saving energy when the pump rotation speed is high.

For this purpose, the present invention has a simple structure, and when the pump rotation speed reaches a predetermined rotation speed, surplus fluid is returned to the pump suction chamber or reservoir to ensure a nearly constant discharge flow rate, and the pump rotation speed is further reduced. The present invention relates to a flow rate control device that is designed to ensure a constant discharge flow rate lower than the predetermined discharge flow rate when the number increases.

The present invention will be explained below based on embodiments shown in the drawings.

FIG. 1 shows an embodiment of the present invention, in which a main body 1 of a flow rate control device includes an inlet 5 communicating with a discharge chamber 3 of a pump 2 via a discharge passage 4, and a fluid operating device 6 such as a power steering device. An inner hole 10 is formed which opens from the pump 2 to the bypass port 9 which communicates with the suction chamber 7 of the pump 2 or the bypass passage 8 which communicates with the reservoir. A spool valve 13 for adjusting the flow rate is movably built into the inner hole 10, and a stopper 14 is fixed to the opening at the other end. , a spring 15 is interposed between the plug body 14 and the spool valve 13, and the spool valve 13 is connected to the base 1.
2 in the direction of contact.

A fluid passage 17 that communicates with the inner hole 10 and a delivery port 16 that communicates with the delivery passage 11 is bored in the mouthpiece 12 , and a first orifice 18 and an orifice are provided in the fluid passage 17 . A second orifice 19 having a narrower passage area than 18 is provided.

The spool valve 13 has a small diameter portion 20 that closes the first orifice 18, and a first portion that isolates the introduction port 5 and the bypass port 9 within the inner hole 10 and controls the opening area of the bypass port 9. The land portion 21 and the pressure chamber 2 of the bypass port 9 and the inner hole 10
2 and a third land portion 24 having a predetermined width, which will be described later, are formed and brought into sliding contact with the inner wall of the inner hole 10. A concave groove 25 between the lands of
26 is formed.

A port 27 opened in the passage between the first orifice 18 and the second orifice 19 of the fluid passage 17 of the mouthpiece 12 is connected to the pressure chamber through a first control passage 28 bored in the main body 1. 22 , and a port 30 bored in the fluid passage 17 downstream of the second orifice 19 of the base 12 communicates with a second control flow passage bored in the main body 1 . 31 via said port 29
A portion closer to the bypass port 9 is communicated with a port 32 opened to the pressure chamber 22 . When the flow rate adjusting spool valve 13 is at the most advanced position due to the elasticity of the spring 15, that is, at the position where it closes the first orifice 18, the third land portion 24 is at the position where it closes the port 32, and The axial width of the third land portion is the width that selectively closes the port 29 or 32, that is, the width that closes both ports 29 and 32 as shown in FIG.
is smaller than the distance a connecting the farthest open ends of , and is equal to or larger than the distance b connecting the closest open ends. Further, a through hole 33 connecting the concave groove 26 and the pressure chamber 22 is bored in the land portion 24 .

The spool valve 13 has a bottomed shaft hole 34, an adjustment nut 35 screwed into the opening thereof, a ball 36 seated on a valve seat formed in a hole passing through the nut 35 in the axial direction, and the ball. A pressure relief valve 38 is provided with a spring 37 that presses the pressure relief valve 36 against the valve seat, and the inner cavity of the shaft hole 34 is communicated with the bypass port 9 through a communication hole 39 bored in the recessed groove 25. There is.

The mouthpiece 12 has a small diameter part 40 whose outer periphery fits into the inner hole 10 and a large diameter part 41 which is screwed into the main body 1, and has an upstream pressure chamber 42 and a downstream pressure chamber in the center thereof. Both chambers 42 and 43 are made by drilling chamber 43.
A second orifice 19 is formed between them to form a fluid passage 17, and a first orifice 19 is formed on the upstream side of the pressure chamber 42.
A plate 44 having an orifice formed therein is tightly fitted thereinto, and a shaft cylinder 45 having a fluid passage bored in the inner wall of the pressure chamber 43 is screwed together.

In the flow control device shown in FIG. 1, the flow rate adjustment spool valve 13 is in a position where it comes into contact with the plate 44 forming the first orifice 18 due to the elasticity of the spring 15, and the third land portion 24 opens the port 29. ,
It is in a position to close the port 32. Further, the first land portion 21 separates the introduction port 5 and the bypass port 9 of the main body 1. In this state, when the pump 2 is driven and fluid is discharged into the inlet 5, the spool valve 13 is activated by the spring ₁ due to the fluid pressure P1 in the inlet 5.
The fluid moves to the left in FIG. 1 against the elasticity of
1 to the fluid operating device 6.

At this time, when the fluid passes through the first orifice 18, a pressure drop occurs, and the fluid static pressure in the pressure chamber 42 is
It becomes P ₂ . Further, when the fluid passes through the second orifice 19, a pressure drop occurs, and the fluid static pressure within the pressure chamber 43 becomes _P3 . Thus, the fluid in the pressure chamber 42 communicates with the pressure chamber 22 via the port 27, the first control flow path 28, and the port 29, but the
is closed by the third land portion 24, so the pressure in the pressure chamber 22 is equal to the pressure in the pressure chamber 42.
Equal to P ₂ .

As the rotational speed of the pump 2 increases, the flow rate of the fluid sent from the fluid passage 17 of the main body 1 to the delivery passage 11 via the delivery port 16 increases gradually, but the spool valve 13 moves to the left. When the first land portion 21 of the spool valve 13 connects the inlet 5 and the bypass port 9, the land portion 21
The flow rate proportional to the area opened by the inlet port 5 is directly bypassed from the inlet port 5 to the bypass port 9, and the discharge flow rate from the fluid passage 16 is increased as the pump rotation speed increases as shown in FIG. 3c-d. Also spool valve 13
is controlled by the differential pressure between P ₁ and P ₂ , and the delivery flow rate is approximately constant. In this state, the spool valve 13 continues to move further to the left until the third land portion 24 opens the port 32 at point d. Then, when the port 32 opens, the pressure inside the pressure chamber ₄₃ increases
are port 30, second control flow path 31, and port 32
is transmitted into the pressure chamber 22 via the pressure chamber 22.
Since the pressure inside becomes the average value of P ₂ and P ₃ , the spool valve 13 moves further to the left due to the difference between this pressure and the pressure P ₁ inside the inlet 5. The opening area of the land portion 21 leading from the inlet 5 to the bypass port 9 increases rapidly, increasing the bypass flow rate.
The fluid flow rate delivered from the pump 6 to the delivery passage 11 decreases as the pump rotation speed increases. When the first land portion 24 of the spool valve 13 closes the port 29, only the fluid pressure _P3 in the pressure chamber 43 downstream of the second orifice 19 acts on the pressure in the pressure chamber 22. From then on, even if the pump rotation speed increases, the spool valve 13 will maintain the pressure inside the inlet 5.
It is controlled by the pressure difference between P ₁ and the pressure P ₃ in the pressure chamber 43 to maintain the delivery flow rate at a low predetermined amount as shown in FIGS. 3e-f.

That is, when the rotation speed of the pump 2 is low, when a predetermined rotation speed is reached, a bypass flow is generated to maintain the delivery flow rate at c-d, and when the pump rotation speed becomes higher, the delivery flow rate is reduced to reach the predetermined rotation speed. This makes it possible to maintain the delivery flow rate of e-f, which is lower than the delivery flow rate of c-d.

When the pressure within the pressure chamber 22 becomes greater than the elastic force of the spring 37 caused by the adjusting nut 35, the pressure relief valve 38 moves the ball 36 away from the valve seat against the elastic force of the spring 37, and A portion of the liquid is discharged from the communication hole 39 through the concave groove 25 to the bypass port 9.

FIG. 4 shows the base 12 in the embodiment shown in FIG.
An orifice 18 as a fluid passage 17 bored in the
19 and pressure chambers 42 and 43, in the axial direction of the cap 112, as the fluid passage 17, the cross-sectional area of the upstream side, that is, the side that communicates with the inner hole 10, is increased, and the cross-sectional area of the upstream side, that is, the side that communicates with the inner hole 10, is increased, and the cross-sectional area of the side that communicates with the inner hole 10 is increased, and A bench lily 50 with a small cross-sectional area on the communicating side is bored and formed, and a port 51 opened in the side wall of the upstream end of the bench lily 50 is connected to the first control flow path 28 on the downstream side of the bench lily 50. Ports 52 opened in the side walls of the ends are communicated with the second control flow path 31, and the fluid pressure in the pressure chamber 42 in FIG.
The pressure P _{2 '} detected by port 51 instead of P ₂ is
Also, instead of the fluid pressure P ₃ in the pressure chamber 43, the port 5
By using the pressure P ₃ ' detected by 2,
The third land portion 24 of the spool valve 13
While port 2 is closed, the spool valve 13 is controlled by the pressure difference of P ₁ - P ₂ ', and after the spool valve 13 closes the port 29, the spool valve 13 is controlled by the pressure difference of P ₁ - P ₃ '. The flow rate control is performed in the same manner as in the embodiment shown in FIG. 1, and other parts denoted by the same reference numerals as in FIG. 1 are the same as in FIG.

In the present invention, an inlet for the discharge fluid of the pump and a bypass port for returning the fluid to the suction chamber or reservoir of the pump are opened in an inner hole in which a spool valve for flow rate control is built, and one end of the inner hole is opened. A fluid passage is formed by forming a first orifice part and a second orifice part in series, and the passage is communicated with the delivery port, and the other end of the inner hole has one end engaged with the end wall. A spool valve for flow rate adjustment is inserted into the inner hole by biasing the stopped spring toward the fluid passage, and the pressure chamber formed between the end wall of the inner hole and the spool valve is a first control passage communicating with the fluid whose pressure has been reduced by the first orifice portion; and a second control passage which makes the pressure chamber communicate with the fluid whose pressure has been reduced by the second orifice portion. and the spool valve is provided with a land portion that controls the opening area of the bypass port and a land portion that selectively closes the first and second control flow paths. Therefore, when the rotational speed of the pump increases and the pump discharge pressure increases, a portion of the fluid discharged from the pump is returned to the pump suction chamber or reservoir by the land portion of the spool valve to the fluid operating device. In addition to controlling the flow rate of the fluid to be sent, this control is carried out by closing one side of the control flow path communicating with the pressure chamber that controls the operation of the spool valve with the land part of the spool valve while the rotational speed of the pump is low, and closing one side of the control flow path with the land part of the spool valve. The lowered pressure of the fluid passing through is applied to control the flow rate to a predetermined speed range in the region of low rotational speed of the pump, and as the rotational speed of the pump increases, the other control flow path is opened and The one control flow path is closed, and the static pressure of the fluid passing through the other orifice is applied to the pressure chamber of the spool valve. This is to control the set flow rate to be lower than that set in the rotational speed region.

The first and second orifice parts, which are constituent elements in the present invention, do not simply mean small-area holes or openings formed in the fluid passage (see Fig. 1); It is clear that this means something that can detect different fluid pressures at different locations in the fluid flow direction of one flow path and use them as control pressures, as shown in the diagram (see figure).

According to the present invention, the flow rate control in the fluid operating device is performed by using the stroke of the flow rate control spool valve and by switching the pressure acting on the back of the spool valve, so the configuration is extremely simple. It is simple, saves power during high-speed operation of the pump, and increases stability. Therefore, when the present invention is applied to a power steering system for an automobile, it occupies less space on the vehicle body, reduces failures, and improves the running stability of the vehicle.
In particular, it can be said that it contributes to high-speed stability and horsepower savings.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of one embodiment of the present invention, Fig. 2 is a partial explanatory diagram thereof, Fig. 3 is a diagram showing the relationship between the pump rotation speed and the delivery flow rate in the embodiment, and Fig. 4
The figure is a sectional view of another embodiment of the present invention. In the figure, 2 is a pump, 6 is a fluid operating device, 1
is the flow control device main body, 5 is the inlet port, 9 is the bypass port, 10 is the inner hole, 13 is the spool valve for adjusting the flow rate,
18 and 19 are orifices, 28 and 31 are control passages, 22 is a pressure chamber, 21, 23, and 24 are land portions of spool valves, 38 is a pressure relief valve, and 50 is a bench lily.

Claims (1)

[Scope of utility model registration request] An inner hole is bored in the main body, which has an inlet for the discharge fluid of the pump and a bypass port for circulating the fluid back to the suction chamber or the reservoir of the pump, and the inner hole communicates with the inlet and the bypass port. A fluid passage having a first orifice part and a second orifice part formed in series is formed at one end, and the passage is communicated with a delivery port for delivering pressurized fluid to the fluid actuating device, and A flow rate adjusting spool valve biased toward the fluid passage by the elasticity of a spring is inserted between the other end wall and the fluid passage, and pressure is generated between the end wall of the inner hole and the spool valve. a first control flow path that communicates the chamber with the pressure drop fluid caused by the first orifice portion; and a second control flow path that causes the pressure chamber to communicate with the pressure drop fluid caused by the second orifice portion; and the spool valve is formed with a land portion that controls the opening area of the bypass port and a land portion that selectively closes the first control flow path and the second control flow path. A flow control device in a fluid actuated device characterized by: