JPH0324878Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a power steering engine stall prevention mechanism provided in an oil pump device that is driven by a vehicle engine and serves as a power source for the steering force of a power steering device.

[Conventional technology]

Conventionally, when a vehicle engine is idling, when a power steering wheel is operated, this load increases the load on an oil pump, which may eventually cause the engine to stall. In order to prevent this engine stall from occurring, increasing the engine speed during idling increases vehicle fuel consumption and becomes uneconomical.
Further, automatic vehicles have a problem in that a creeping phenomenon occurs strongly in the D or R range, which is the transmission range of the torque converter.

[Problem that the invention attempts to solve]

As mentioned above, this invention solves the problem of engine stalling that occurs when vehicle engines are idling.When the power steering is operated, if the engine speed drops below the set value due to this load, the system automatically The object of the present invention is to provide an engine stall prevention mechanism for an oil pump device for power steering, which reduces the load on power steering.

[Specific measures to solve the problem]

As a result of intensive research into specific means to solve the above-mentioned problem, the inventor of the present invention has determined that the following means are possible.
The present invention was completed after discovering that when the engine is idling, the load on the oil pump is reduced when the power steering is operated. That is, the present invention provides an oil pump device for power steering equipped with a flow control valve that sequentially passes oil discharged from an oil pump through a spool chamber, an orifice, and a discharge chamber to supply the power steering device. a spool chamber consisting of a first and a second spool chamber communicating with the oil pump and having a discharge port for returning discharged oil to the oil pump;
The engine stall prevention spool is biased by a cooperation between a compression spring housed in the spool chamber and the hydraulic pressure in the second spool chamber to open and close the discharge port of the spool chamber.

[Effect]

The engine stall prevention mechanism of the power steering oil pump device of the present invention is such that when the engine is idling and the power steering is operated, the reaction force from the tires becomes excessively large and the engine succumbs to the load of the power steering pump. When the rotation speed decreases, the sum of the spring force of the compression spring housed in the second spool chamber and the oil pressure in the second spool chamber becomes greater than the oil pressure in the first spool chamber, and the engine stall prevention spool is activated. It moves in the direction of opening the discharge port, and part of the discharged oil in the spool chamber is returned to the oil pump from the discharge port. This reduces the load on the oil pump and prevents engine stalling.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

The engine stall prevention mechanism 1 of the oil pump device for power steering according to the present invention includes an oil pump 2
The flow control valve 3 is connected to a flow control valve 3 to which oil discharged from the flow control valve 3 is supplied.

Hydraulic oil is supplied to the oil pump 2 from the outside through a suction port (not shown), the hydraulic oil is kept at high pressure by a vane plate 4, and the discharged oil flows through an oil passage 6 from a discharge port 5. The spool chamber 8 of the flow control valve 3 is supplied thereto.
The supply flow rate is from the spool chamber 8 to the orifice 1.
0 from the discharge chamber 11 to the gearbox (not shown) of an external power steering device, and the flow rate discharged from the discharge port 13 communicating with the bypass passage 12 communicating with the oil pump 2. It has become a branching flow.

The hydraulic pressure PB in the discharge chamber 11 is supplied to the back pressure chamber 16 of the spool 15 via the oil path 14, and the spool 15 is connected to the hydraulic pressure PB in the back pressure chamber 16 and the back pressure chamber 1.
The discharge port 13 is opened and closed by being biased by the cooperation of the spring force F ₁ of the compression spring 18 housed in the discharge port 6 .

The engine stall prevention device 1 includes an engine stall prevention spool 21 that is slidably inserted into a spool chamber 20, and the spool chamber 20 is connected to the first and second spool chambers 2 by the engine stall prevention spool 21.
It is divided into 2 and 23 parts. First spool chamber 2
2 is connected to the spool chamber 8 of the flow control valve 3 through a branch passage 25 branching from the oil passage 6, and the second spool chamber 23 is connected to the spool chamber 8 of the flow control valve 3 through a branch passage 26 branching from the oil passage 14. It communicates with the discharge chamber 11. A discharge port 29 is formed in the spool chamber 20 and communicates with a low pressure side passage 28 branched from the bypass passage 12. Further, the low pressure side passage 28 communicates with the reservoir 30.

Therefore, the first spool chamber 22 has a branch pipe 25.
The hydraulic pressure PA is supplied to the second spool chamber 23 via the oil passages 14 and 26, and the hydraulic pressure PB of the discharge chamber 11 is supplied to the second spool chamber 23 via the oil passages 14 and 26. hydraulic pressure PB and the compression spring 3 housed in the second spool chamber 23.
The discharge port 29 is opened and closed by being biased by the cooperative action with the spring force F2 of the discharge port ₂₉ .

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

The rotational speed of the oil pump 2 increases as the engine rotational speed increases, and the discharge flow rate from the oil pump 2 increases accordingly. Then, the pressure difference PD between the hydraulic pressure PA in the spool chamber 8 and the hydraulic pressure PB in the discharge chamber 11 increases, and the hydraulic pressure PA becomes larger than the sum of the hydraulic pressure PB and the spring force F ₁ of the compression spring 18 .
As a result, the spool 15 moves to the right, the discharge port 13 is opened, and a part of the supplied flow flows out into the bypass passage 12 and is returned to the oil pump 2.
Thereby, the discharge flow rate from the discharge chamber 11 is always maintained substantially constant.

Here, when the power steering is operated while the engine is idling (engine speed is 500 to 600 VPm), the engine speed decreases due to the load on the power steering. Along with this, the rotational speed of the oil pump 2 also decreases, and the flow rate supplied from the discharge port 5 to the spool chamber 8 decreases.
Pressure difference PD becomes smaller. At the same time, the pressure difference PD between the first spool chamber 22 and the second spool chamber 23 becomes smaller, and the pressure difference between the second spool chamber 23 hydraulic pressure PB and the compression spring 31 is lower than that of the first spool chamber 22 hydraulic pressure PA.
When the sum of the spring force _F2 becomes larger, the engine stall prevention spool 21 moves to the right and closes the discharge port 2.
9 is opened, the flow rate in the second spool chamber 23 is discharged from the discharge port 29, and is returned to the oil pump 2 through the low pressure side passage 28. As a result, the oil pressure supplied from the discharge chamber 11 to the power steering is reduced, and the load on the oil pump 2 is reduced.
In this way, when the differential pressure PD becomes less than the set value, that is, the engine speed becomes less than the set value, the oil pressure supplied to the power cylinder is reduced, and the load on the oil pump 2 can be reduced, thereby increasing the engine speed. It is possible to prevent a decline in the number of
Engine stall is prevented.

〔effect〕

The engine stall prevention mechanism for power steering of this invention reduces the oil pressure supplied to the power steering when the engine speed drops below a set value due to the load on the power steering when the engine is idling, reducing the load on the oil pump. This makes it possible to prevent engine stalls from occurring.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an engine stall prevention mechanism for a power steering oil pump device according to the present invention. DESCRIPTION OF SYMBOLS 1... Engine stall prevention mechanism, 2... Oil pump, 3... Flow control valve, 8... Spool chamber of flow control valve 3, 10...
...orifice, 11...discharge chamber, 20...spool chamber consisting of first and second spool chambers 22, 23, 29...discharge port, 31...compression spring.

Claims (1)

[Scope of utility model registration request] The oil discharged from the oil pump is sequentially transferred to the spool chamber.
In a power steering oil pump device provided with a flow control valve for supplying oil to a power steering device through an orifice and a discharge chamber, the oil pump device comprises first and second spool chambers communicating with the spool chamber and the discharge chamber, respectively; a spool chamber forming a discharge port for returning oil to the oil pump; a compression spring slidably fitted into the spool chamber and housed in the second spool chamber; and a hydraulic pressure in the second spool chamber. An engine stall prevention mechanism for a power steering oil pump device, comprising: an engine stall prevention spool that is energized in cooperation with the engine stall prevention spool to open and close the discharge port of the spool chamber.