JPS6358139B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure fluid supply device that selectively supplies pressure fluid discharged from a plurality of pumps to fluid equipment.

For example, in a power steering device mounted on an automobile to reduce the steering force of a driver, a pump that is a source of oil pressure generation is usually rotationally driven by the engine of the automobile. The amount of hydraulic oil discharged from this pump increases or decreases in proportion to the engine speed. Therefore, such a pump needs to have a capacity that can supply a sufficient flow rate without interfering with the operation of fluid equipment such as the power steering device even in a low engine speed range, that is, when the pump discharge amount is small. required.

However, if you set the pump capacity like this,
In the high speed range of the engine, an unnecessarily large flow rate is supplied to the power steering device, which is not only wasteful, but also increases the horsepower consumption of the engine to drive this pump, which is not desirable from an energy-saving measure. . In particular, in recent years there has been a call for improved fuel efficiency of automobile engines, and it is desired to minimize the horsepower consumption of the pump for the power steering device described above.

For this reason, conventionally, a pair of pressure chambers installed at symmetrical positions in one pump cartridge are separated and used as two pumps, or two pumps with small capacities are installed separately. A pressurized fluid supply device has been proposed in which pressure fluid from both pumps is selectively supplied to a fluid device using a flow path switching mechanism that operates according to the discharge amount of the fluid. In this type of device, when the discharge volume of each pump is small, these are combined and supplied to ensure a sufficient flow rate for fluid equipment operation, and when the discharge volume of each pump becomes large, only one pump is supplied. is used for hydraulic pressure supply, and the other is connected to the tank side to be in an unloaded state, thereby minimizing the horsepower required to drive the pump and reducing the horsepower consumption.

Therefore, the above-mentioned device guarantees a sufficient supply amount to the fluid equipment regardless of whether the engine speed is in the low or high speed range, while reducing pump horsepower consumption and saving energy. Although this is a great advantage in that it can be used as a power steering device, the problem is that when such a device is used as a power steering device, it lacks running stability when the vehicle is running at high speed. . Of course, this type of equipment has traditionally been equipped with a flow rate control valve to prevent malfunction of fluid equipment due to excessive flow rate, and is configured to return pressurized oil exceeding a predetermined value to the tank side, but the above-mentioned running stability Gender-related issues remain unresolved.

In other words, in a power steering system, the largest amount of supply is required when steering the vehicle while the vehicle is stopped or running at low speed, and in this case it is desirable to reduce the steering force as much as possible. . This is because the steering wheel is heavy and requires large operations when the vehicle is stopped or driving at low speeds.

On the other hand, when the automobile is running at high speed, it is preferable that the amount of pressure oil supplied is small. This is because if the steering wheel is too light when driving at high speeds, it will cause the driver to feel uneasy, which is a problem in terms of steering performance. It is preferable from a safety standpoint. In particular, when the vehicle is traveling at such high speeds, the steering wheel is rarely operated significantly, and the amount of pressure oil supplied may be smaller than when traveling at low speeds.

This requirement is greater for passenger cars, which are lighter than large vehicles such as trucks, and is necessary to ensure their running stability.

As a means to solve these problems, a so-called drooping mechanism has been developed that allows the flow rate control unit connecting the pump and power steering device to reduce the amount of pressurized oil supplied to a certain degree in the high speed range of the engine. It is common practice to attach
This type of drooping mechanism is also effective in reducing energy loss by reducing the amount of pressure oil supplied to the power steering device during high-speed driving, thereby minimizing pressure loss in the piping and power steering device. There is, and it is useful.

However, a drooping mechanism with such advantages has not yet been incorporated into the energy-saving pressurized fluid supply device described above, and a device with a simple configuration that also has these advantages has not yet been realized. Appearance is requested.

The present invention was made in view of the above-mentioned circumstances, and it selectively switches the flow path of pressure fluid from a plurality of pumps, and performs a drooping effect by using a flow control valve that controls the amount of fluid supplied. The simple configuration of forming a variable orifice not only eliminates wasted horsepower consumption of the pump and achieves a greater energy-saving effect, but also significantly improves performance according to the operating characteristics of the fluid equipment side. The present invention provides a pressurized fluid supply device that can

Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

FIG. 1 shows an embodiment of a pressure fluid supply device according to the present invention, and in this embodiment, a case where the pressure fluid supply device is applied to a power steering device for an automobile will be explained.

In the figure, reference numerals 1 and 2 indicate first and second pumps that discharge pressure oil separately, and both are rotationally driven by an engine (not shown). Both pumps 1 and 2 play the role of circulating and supplying hydraulic oil in the tank 3 to the power steering device 5 via the flow rate control section 4.

Note that these pumps 1 and 2 do not necessarily need to be constructed separately, but may be constructed integrally with a common casing and pump drive shaft, or even provided at symmetrical positions in one pump cartridge. A pair of pressure chambers may be used as separate pumps. In this case, as will be described later, it is possible to further increase the energy saving effect by making the capacity of the first pump 1 used as the main pump smaller than that of the second pump 2.

Further, in the figure, 1a and 2a are suction side pipes of each pump 1 and 2, 1b and 2b are discharge side pipes, and 3a is a tank side pipe connected to the pipes 1a and 2a,
Furthermore, 5a is the flow rate control section 4 and the power steering device 5.
The pressure oil supply pipe 5b in between is a return pipe to the tank 3.

Now, according to the present invention, the flow rate control section 4 for selectively supplying the pressure oil discharged from the first and second pumps 1 and 2 to the power steering device 5 is configured as follows. are doing.

That is, the reference numeral 10 in the figure indicates the first pump 1.
A main passage 11 is a sub passage through which pressure oil from the second pump 2 is guided; The main passage 10 or the tank 3 is controlled by the flow control valve 12 which is provided with a flow path switching mechanism A that operates depending on the magnitude of the oil flow rate.
selectively connected to the side.

To explain this in detail, 13 in the figure has one end connected to the passage 14.
A valve hole is formed in the casing 4a so that the other end crosses the downstream side of the main passage 10, and the valve hole 13 is connected to the upstream side of the main passage 10 through the valve hole 13. 1
Flow rate control valve 1 that controls the flow rate during 0 to below a certain value
A spool 15 forming part 2 is slidably disposed. The spool 15 is normally urged toward the passage 14 by a spring 16 disposed inside the valve hole 13.
The orifice 17, which is provided at the downstream opening of the main passage 10 that traverses the main passage 10, is slid within the valve hole 13 in response to the fluid pressure difference generated before and after the orifice 17. That is, the fluid pressure on the upstream side of the orifice 17 is transmitted to the high pressure chamber 18 formed on the passage 14 side of the spool 15 via the passage 14, and the fluid on the downstream side of the orifice 17 is transmitted to the low pressure chamber 19 provided with the spring 16. Pressure is introduced through the passages 20, respectively, and the spool 15 is actuated by the pressure difference in the two chambers 18, 19, which changes depending on the flow rate of the pressure oil flowing through the main passage 10.

In addition, 21 is an annular groove formed on the outer periphery of the spool 15 so as to communicate with the opening of the main passage 10 that crosses the valve hole 13 when the spool 15 is not in operation, and 22 is an annular groove provided inside the spool 15. 20a is a relief valve, and 20a is a passage 20
This is an orifice installed in the middle of the valve to prevent valve oscillation.

In the flow rate control valve 12 configured as described above, the sub passage 11 opens at the axial center of the valve hole 13, and is connected to the through hole 23b via the annular groove 23a on the outer periphery of the spool 15. . Further, this through hole 23b and the end of the spool 15 on the high pressure chamber 18 side are communicated via a passage 23c, and the flow of pressure oil between the sub passage 11 and the main passage 10 is controlled in the middle of this passage 23c. A check valve 24 is provided to prevent this. Further, a drain passage 25 is opened in a portion of the valve hole 13 adjacent to the high pressure chamber 18, and the drain passage 25 allows pressure oil to flow back to the tank 3 via a return pipe 25a. The high pressure chamber 18 is opposed to the annular groove 26 provided on the outer periphery near the front end of the high pressure chamber 18,
It is separated from the sub passage 11.

Therefore, when the flow control valve 12 is in the non-operating state, the pressure oil from the second pump 2 flows through the sub passage 11 and the annular groove 23 of the spool 15.
a, through the through hole 23b and the passage 23c, and the check valve 2
4 is opened to flow to the high pressure chamber 18 side, and then to the passage 1.
4, the pressure oil from the first pump 1 is merged with the pressure oil from the first pump 1 in the main passage 10, and as a result, the pressure oil from both pumps 1 and 2 flows into the power steering device 5, as shown by the solid line a in FIG. supplied to And main passage 10
When the flow rate of the pressure oil inside exceeds a predetermined value and the spool 15 moves toward the low pressure chamber 19 side due to the pressure difference generated before and after the orifice 17, the high pressure chamber 18 and the drain, which were separated by the land portion 26a of the spool 15, are separated. The passage 25 is connected, and as a result, part of the pressure oil in the main passage 10 flows back to the tank 3 side, and at the same time, the land portion 26b is also removed to connect the sub passage 11 to the drain passage 25. Therefore, the pressure oil from the second pump 2 returns to the tank 3 side by an amount corresponding to the amount of movement of this spool 15, and the rest is guided to the main passage 10 side via the check valve 24, As a result, the amount of power supplied to the power steering device 5 is maintained at a constant amount as shown by the solid line b in FIG. and,
When the pump rotation speed increases and it becomes possible to guarantee a sufficient supply amount with only the pressure oil from the first pump 1, the second pump 2 is completely connected to the tank 3 side and kept in an unloaded state. As a result, the horsepower consumed for driving becomes unnecessary, making it possible to achieve energy savings.

Now, in the flow control valve 12 equipped with the flow path switching mechanism A as described above, what should be noted is that among the annular grooves formed on the outer periphery of the spool 15, the annular groove forming a part of the main passage 10 A small diameter portion 27 is formed close to the groove 21 on the high pressure chamber 18 side, that is, on the opposite side to the moving direction of the spool 15, and this small diameter portion 27 covers the opening of the main passage 10 as the spool 15 moves. , and this opening to form a variable orifice.

That is, the power steering device 5 is required to provide a certain degree of rigidity to the steering wheel and improve running stability when the engine is in a high speed rotation range, that is, when the vehicle is traveling at high speed. In order to satisfy this requirement, it is necessary to reduce the amount of pressure oil supplied from the pump to some extent (generally referred to as drooping effect). The above-mentioned variable orifice was developed in response to such a request, and the pump rotation speed is high and the spool 15 is moved to the low pressure chamber 19.
When the main passage 10 is sequentially moved to the side, the main passage 10 is constricted, thereby acting to reduce the amount of supply to the power steering device 5 as shown by the solid line c in FIG.

In addition, in FIG. 2, P ₁ is the discharge amount from the first pump 1, P ₂ is the discharge amount from the second pump 2, and P ₁ +
P ₂ indicates the combined discharge amount from both pumps 1 and 2, respectively.

Further, in this embodiment, the variable orifice that performs the drooping action described above is formed by the orifice 17 for sensing the flow rate in the main passage 10 and the small diameter portion 27 of the spool 15, as shown in FIG. It is structured so that the effect works more effectively.

According to the pressure fluid supply device having such a configuration, when the pump rotation speed is low and the discharge amount from both pumps 1 and 2 is small, the fluids are combined and supplied to provide a sufficient supply amount to the power steering device 5. At the same time, when the pump rotation speed reaches a point at which a sufficient supply amount can be obtained with only one pump, the other pump is disconnected to reduce its horsepower consumption, thereby achieving energy savings. Furthermore, when the pump rotation speed increases, a drooping effect works as the spool 15 moves, reducing the supply amount, ensuring the operation of the power steering device 5, and improving the running stability of the automobile at high speeds. Furthermore, by reducing the supply amount due to this drooping effect, the back pressure applied to the pump side can be reduced, and the pressure loss due to piping can be reduced, further increasing the energy saving effect. It becomes possible.

3 to 7 show other embodiments of the present invention, and the same or corresponding parts as in FIG. 1 are given the same reference numerals and their explanation will be omitted.

First, in the embodiment shown in FIG.
This shows a case in which the check valve 24 that connects the sub-passage 11 and the check valve 24 is provided directly in the casing 4a, and the flow path is switched in accordance with the operation of the flow control valve 12, which is the same as in the embodiment described above. It is. This not only simplifies the configuration of each part, but also
The valve length of the flow rate control valve 12 can be shortened, which is advantageous for downsizing.

Further, in the embodiment shown in FIG. 4, the main passage 1
The arrangement position of the check valve 24 between the main passage 10 and the sub passage 11, the main passage 10, the sub passage 11, and the drain passage 2
Although there are some differences in the connection structure with 5 and the shape of the spool 15, it is clear that the effects are the same as those of the two embodiments described above.

Further, in FIG. 5, the main passage 10 is provided separately from the flow control valve 12, and the main passage 10 is provided separately from the flow control valve 12.
This shows the case where the bypass passage 30 crosses the flow rate control valve 12. A small diameter portion 31 formed in the opening portion of the bypass passage 30 facing the valve hole 13 and an annular groove 32 on the outer periphery of the spool 15
This constitutes a variable orifice that performs the drooping action described above. Main passage 1 like this
It will be easily understood that even if the bypass passage 30 is attached to the bypass passage 30, the flow passage will still be constricted, and the same effect as described above will be achieved.

Further, in the embodiment shown in FIG. 6, a rod 40 having a tapered portion 40a is attached to the spool 15 constituting the flow control valve 12, and a small diameter portion 41 in the valve hole 13 formed around the rod 40 is attached.
and form an orifice 17. Then, by moving the spool 15, the tapered portion 40a is made to correspond to the small diameter portion 41, and the main passage 10 is
The structure is such that a drooping effect is exerted by narrowing down the area.

Further, in the embodiment shown in FIG. 7, the main passage 1
0 is formed along the axial direction of the spool 15 of the flow control valve 12, and the orifice 17 is formed in the valve hole 1.
The rod 50 has a tapered portion 50a projecting in the axial direction of the rod 50 and a small diameter portion 51 on the spool 15 side. Of course, it will be easily understood that such a configuration also produces the same effects as described above.

In addition, in each of the above-mentioned embodiments, a case was explained in which two pumps 1 and 2 were used as the pressure oil supply source, but the present invention is not limited to this, and a plurality of pumps are used, and one of them It goes without saying that it may be configured such that one pump is used as a main pump, and the remaining pumps are connected as sub-pumps to the main passage so as to join together.

As explained above, according to the pressure fluid supply device according to the present invention, drooping is performed using a flow control valve that selectively switches the flow path of pressure fluid from a plurality of pumps and controls the supply amount. By forming a variable orifice that performs the action, although it has a simple configuration, the supply amount can be controlled more rationally than before, eliminating wasted horsepower consumption of the pump, and further improving the energy-saving effect. Furthermore, it is possible to guarantee the supply amount according to the operating characteristics of the fluid equipment side, and to significantly improve the performance of the fluid equipment. In particular, the device of the present invention has the advantage that when used in a power steering device, it not only can make the running stability of an automobile even safer, but also can greatly contribute to improving fuel efficiency.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment in which the pressure fluid supply device according to the present invention is applied to a power steering device;
The figure is a characteristic diagram showing the flow control characteristics, and FIGS. 3 to 7 are system diagrams showing other embodiments of the present invention. DESCRIPTION OF SYMBOLS 1...1st pump, 2...2nd pump, 3...tank, 4...flow control part, 5...power steering device, 10
...Main passage, 11...Sub passage, 12...Flow rate control valve, 15...Spool, 17...Flow rate detection orifice, 24...Check valve, 25...Drain passage, 27...Small diameter section, 30...Bypass passage, 31...Small diameter Part, 32
...Annular groove, 40...Rod, 40a...Tapered part, 4
1...small diameter part, 50...rod, 50a...tapered part,
51...Small diameter part.

Claims (1)

[Claims] 1. A first and second pump that separately discharges pressure fluid, a main passage that supplies the pressure fluid from the first pump to the fluid equipment, and a main passage that is connected in the middle of the main passage and that supplies the pressure fluid from the second pump. a sub-passage that joins the pressure fluids of the main passage through a check valve; A flow control valve having a spool inside which returns a part of the pressure fluid to the tank, and having a flow path switching function that connects the sub passage to the tank side when the spool is operated, and the flow rate control valve. 1. A pressure fluid supply device comprising a variable orifice that throttles the main passage or its bypass passage to restrict the flow rate of pressure fluid by operating a spool of a valve to perform a drooping action.