JP2008189106A - Power steering device for automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power steering device for an automobile improved in safety and reliability as the whole of the device by preventing excessive rises of hydraulic pressure and oil temperature within a hydraulic pump. <P>SOLUTION: This power steering device is provided with a bypass circuit Lb detouring around a gear box 2 to communicate a high pressure circuit L1 with a lower pressure circuit L2 and interposed with a switching valve 4 and a pressure regulating valve 5 in a flow passage, an oil temperature detection means 6 interposed in the high pressure circuit L1 including the hydraulic pump 1, and a control means 10. When a value detected by the oil temperature detection means 6 becomes a prescribed value or more, the control means 10 is constituted to switch a flow of the high pressure circuit L1 to the bypass circuit Lb. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydraulic pump that is a source of hydraulic pressure and has a relief circuit, a steering gear box that converts hydraulic pressure into steering assist force, a high-pressure circuit that communicates from the hydraulic pump to the gear box, and a hydraulic pump from the gear box to the hydraulic pump. The present invention relates to a power steering apparatus for an automobile having a low-pressure circuit in communication.

FIG. 4 shows a configuration of a conventional power steering apparatus for an automobile.
In FIG. 4, the automobile power steering apparatus includes a hydraulic pump 1, a steering gear box (hereinafter abbreviated as a gear box) 2, and a hydraulic tank 3.

The discharge port 1o of the hydraulic pump 1 and the suction port 2i of the gear box 2 are connected by a high-pressure circuit L1.
The discharge port 2o of the gear box 2 and the return port 3i of the oil tank 3 are connected by a low pressure circuit L2.
The discharge port 3o of the oil tank 3 and the suction port 1i of the hydraulic pump 1 are connected by an oil supply circuit L3.
The hydraulic pump 1 is provided with a relief circuit Lr (for example, a relief circuit of a type incorporated in the pump 1) to prevent the hydraulic pressure of the high-pressure circuit L1 from rising above a predetermined value (relief pressure). .

However, for example, when pressure oil continues to circulate through the relief circuit Lr of the hydraulic pump 1 as in the case where steering is continued while the steering wheel is pressed against the curb of the road, the oil temperature inside the hydraulic pump 1 is increased. It will rise excessively.
An excessive rise in the oil temperature inside the pump 1 causes poor lubrication of the sliding portion of the hydraulic pump 1 and causes “burn-in” or “galling” of the sliding portion.
When the “burn-in” or “galling” of the sliding part continues for a long time, there is a risk of causing a malfunction of the entire apparatus and causing a serious accident.

On the other hand, a variable displacement pump capable of obtaining a discharge amount corresponding to the vehicle speed and the steering angle is disclosed (see, for example, Patent Document 1 and Patent Document 2).
However, Patent Document 1 aims to feed the minimum amount of oil when the steering assist force is unnecessary, and to suppress the power consumption at the time of driving the pump to the minimum necessary. It is not something to eliminate.

Patent Document 2 is intended to obtain a required steering assist force by the power steering device by performing drive control according to traveling conditions such as a vehicle speed, a steering state, and an operating state on the power steering device side, The above-mentioned problems cannot be solved.
JP 2001-159395 A JP 2001-294166 A

  The present invention has been proposed in view of the above-mentioned problems of the prior art, and prevents the excessive increase in the hydraulic pressure and oil temperature in the hydraulic pump, thereby improving the safety and reliability of the entire apparatus. The purpose is to provide a steering device.

  A power steering apparatus (100) for an automobile according to the present invention includes a hydraulic pump (1) having a relief circuit (Lr) (which is a source of hydraulic pressure) and a steering gear box (2) for converting hydraulic pressure into steering assist force. And a high pressure circuit (L1) communicating from the hydraulic pump (1) to the gear box (2) and a low pressure circuit (L2) communicating from the gear box (2) to the hydraulic pump (1). In FIG. 2, a bypass circuit (Lb) that bypasses the gear box (2) and connects the high-pressure circuit (L1) and the low-pressure circuit (L2) is provided, and the bypass circuit (Lb) includes an on-off valve (4) and a flow control device. (For example, a pressure regulating valve 5 or an orifice) is provided, and an oil temperature detecting means (6) and a control means (10) disposed on the high pressure circuit side are provided, and the control means (10) When the value detected by the oil temperature detecting means (6) exceeds a predetermined value, the flow of the high-pressure circuit (L1) is controlled to be switched to the bypass circuit (Lb). (Claim 1).

  The place where the oil temperature detecting means (6) is interposed is inside the hydraulic pump (1).

  The place where the oil temperature detecting means (6) is interposed is in the vicinity of the hydraulic pump (1) in the high pressure circuit (L1).

  The flow regulating device is a pressure regulating valve (5), and the valve opening pressure (P2) of the pressure regulating valve (5) is set lower than the relief pressure (P1) of the hydraulic pump (1). ).

  A warning means (buzzer 7 and / or warning light 8) is provided, and the control means (10) provides warning means (buzzer 7 and / or buzzer 7) when the value detected by the oil temperature detection means (6) exceeds a predetermined value. Alternatively, control for operating the warning light 8) is performed (claim 5).

  Here, it is preferable to interpose a heat exchanger for cooling (9) in the bypass circuit (Lb).

  According to the present invention having the above-described configuration, the control means (10) bypasses the flow of the high-pressure circuit (L1) when the value detected by the oil temperature detection means (6) exceeds a predetermined value. Since it is configured to switch to Lb), an abnormal increase in the oil temperature in the hydraulic pump (1) and the high-pressure circuit (L1) can be avoided.

  In the present invention, warning means (buzzer 7 and / or warning light 8) is provided, and warning means (buzzer 7 and / or warning) are provided when the value detected by the oil temperature detection means (6) exceeds a predetermined value. If the lamp 8) is configured to operate (Claim 5), even if the oil temperature rises higher than usual, the warning means (buzzer 7 and / or warning lamp 8) will operate, and the driver will promptly Such a situation can be noticed and dealt with early (for example, the end cutting operation can be stopped).

  If the cooling heat exchanger (9) is interposed in the bypass circuit (Lb), a temperature lowering effect can be further obtained, and durability and reliability can be improved.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
1 and 2 show a first embodiment of the present invention.
In FIG. 1, a power steering apparatus for an automobile, indicated as a whole by reference numeral 100, has a hydraulic pump 1, a steering gear box (gear box) 2, and an oil tank 3.

The discharge port 1o of the hydraulic pump 1 and the suction port 2i of the gear box 2 are connected by a high-pressure circuit L1.
The discharge port 2o of the gear box 2 and the return port 3i of the oil tank 3 are connected by a low pressure circuit L2.
The discharge port 3o of the oil tank 3 and the suction port 1i of the hydraulic pump 1 are connected by an oil supply circuit L3.

The hydraulic pump 1 includes a relief circuit Lr. A clear illustration of how the relief circuit Lr is built in the hydraulic pump 1 is omitted.
When the hydraulic pressure in the hydraulic pump 1 exceeds the relief pressure (P1), the hydraulic pressure generated in the hydraulic pump 1 is not discharged to the high-pressure circuit L1, but circulates through the relief circuit Lr in the hydraulic pump 1. It is configured.

  A branch point B is formed in the high voltage circuit L1, and a junction point G is formed in the low voltage circuit L2. The branch point B of the high voltage circuit L1 and the junction point G of the low voltage circuit L2 are communicated with each other by a bypass circuit Lb.

On the side close to the branch point B of the bypass circuit Lb, an on-off valve 4 is interposed.
On the side of the bypass circuit Lb near the junction G, a pressure regulating valve 5 is interposed as a flow rate adjusting device. In place of the pressure regulating valve 5, an orifice (not shown) may be interposed.
The opening / closing pressure P <b> 2 of the pressure regulating valve 5 is set lower than the relief pressure P <b> 1 of the hydraulic pump 1. Note that the difference between the opening / closing pressure P2 of the pressure regulating valve and the relief pressure P1 is set on a case-by-case basis in consideration of the vehicle type, engine model, and usage conditions.

In the illustrated embodiment, an oil temperature sensor 6, a control unit 10 that is a control unit, a buzzer 7 that is a warning generation unit, and a warning lamp 8 are provided.
The control unit 10 is connected to the temperature sensor 6 through an input signal line Si. The control unit 10 is connected to the buzzer 7, the warning lamp 8, and the on-off valve 4 through the control signal line So.
The oil temperature sensor 6 is provided in the hydraulic pump 1 in the illustrated embodiment. However, the temperature sensor 6 can also be arranged in a region near the hydraulic pump 1 in the high-pressure circuit L1.

  The control unit 10 is configured to open the on-off valve 4 interposed in the bypass circuit Lb and operate the buzzer 7 and the warning lamp 8 when the value detected by the oil temperature sensor 6 exceeds a predetermined value. ing.

As described above, the bypass circuit Lb includes the pressure regulating valve 5 whose valve opening pressure is set to the pressure P2. Therefore, when the on-off valve 4 is opened, if the pressure in the bypass circuit Lb is P2 or more, the pressure regulating valve 5 is opened, and the pressure oil flows through the bypass circuit Lb.
When the pressure in the bypass circuit Lb is less than P2, the pressure regulating valve 5 remains closed, and the pressure oil does not flow through the bypass circuit Lb. However, when the value detected by the oil temperature sensor 6 is equal to or greater than a predetermined value, the pressure of the oil discharged from the hydraulic pump 1 usually rises above the pressure P2, so that the on-off valve 4 is opened. If it is, the pressure regulating valve 5 is also opened. Alternatively, the valve opening pressure P2 of the pressure regulating valve 5 is set to a numerical value such that the pressure of the oil discharged from the hydraulic pump 1 reaches when the value detected by the oil temperature sensor 6 is a predetermined value or more. .

  Here, since the valve opening pressure P2 of the pressure regulating valve 5 is equal to or less than the relief pressure P1, when the steering wheel is continuously steered while being pressed against the curb of the road, before the pressure oil circulates through the relief circuit Lr. In the stage, the pressure oil discharged from the hydraulic pump 1 flows through the bypass circuit Lb. That is, the pressure oil discharged from the hydraulic pump 1 circulates so as to flow through the high pressure circuit L1, the bypass circuit Lb, the low pressure circuit L2, and the oil tank 3 and return to the pressure oil pump 1. And while flowing through the circulation path, the pressure oil falls. Therefore, the temperature rise does not occur as in the case where only the relief circuit Lr is circulated.

Further, since the valve opening pressure P2 of the pressure regulating valve 5 is equal to or lower than the relief pressure P1, when the value detected by the oil temperature sensor 6 exceeds a predetermined value, the pressure oil discharged from the hydraulic pump 1 is relieved. It flows through the circulation path including the bypass circuit Lb without flowing through the circuit Lr.
However, if an abnormality of a type different from that described above occurs and the hydraulic pressure in the hydraulic pump 1 rises without increasing the oil temperature, the hydraulic pump 1 can be activated if the hydraulic pressure exceeds the relief pressure P1. The discharged pressure oil flows through the relief circuit Lr and stops flowing into the high-pressure circuit L1.

Based on the flowchart of FIG. 2, the control in 1st Embodiment of FIG. 1 is demonstrated.
In FIG. 2, first, the oil temperature in the hydraulic pump 1 is detected by the oil temperature sensor 6 (step S1).
In the next step S2, the control unit 10 determines whether or not the temperature detected by the oil temperature sensor 6 (oil temperature in the hydraulic pump 1) has reached or exceeded a predetermined value (threshold value).

If the oil temperature in the hydraulic pump 1 is equal to or higher than the predetermined value (YES in step S2), the process proceeds to step S3.
If the oil temperature in the hydraulic pump 1 is less than the predetermined value (step S2 is NO), the process proceeds to step S6.

In step S3, the on-off valve 4 interposed in the bypass circuit Lb is opened, and the buzzer 7 and the warning lamp 8 are operated (step S4). And the state as it is is maintained for a predetermined time (step S5 is NO loop).
If the predetermined time has elapsed (YES in step S5), the process returns to step S1, and step S1 and subsequent steps are repeated again.

  On the other hand, if the oil temperature is lower than the predetermined value (step S2 is NO), the on-off valve is closed (step S6), and it is confirmed that the buzzer 7 and the warning lamp 8 are OFF (step S7), and step S1. Returning to step S1, the steps after step S1 are repeated.

  According to the first embodiment having the above-described configuration, when the value detected by the oil temperature sensor 6 exceeds a predetermined value, the flow of the high-pressure circuit L1 is switched to the bypass circuit Lb. An abnormal increase in the oil temperature in the pump 1 and the high-pressure circuit L1 can be avoided.

Further, a buzzer 7 and a warning light 8 are provided as warning means, and the buzzer 7 and the warning light 8 are operated when the value detected by the oil temperature sensor 6 by the control unit 10 exceeds a predetermined value. Has been.
Accordingly, when the oil temperature rises, the buzzer 7 and the warning light 8 are activated, so that the driver notices the situation that the oil temperature is rising quickly and takes action early (for example, the end cutting operation is stopped). be able to.
Note that either the buzzer 7 or the warning light 8 or both may be omitted.
Further, the buzzer may be replaced with a sound alarm device.

Next, a second embodiment will be described with reference to FIG.
In FIG. 3, the power steering apparatus denoted by reference numeral 101 as a whole is provided with an oil cooler 9, which is a heat exchanger for cooling pressure oil, in a region between the pressure regulating valve 5 and the junction G in the bypass circuit Lb. is doing.

As a heat exchange system (cooling system) of the oil cooler 9, a refrigerant (for example, engine cooling water) may be introduced, or an air cooling system using a finned tube of a predetermined length may be used.
When the air cooling method is adopted, the length of the bypass circuit Lb may be increased, and the oil cooler 9 may be disposed in a place with good ventilation.

  The effect of the second embodiment is improved in the temperature lowering effect of the pressure oil as compared with the effect of the first embodiment, and the troubles associated with the oil temperature increase can be avoided reliably.

  It should be noted that the illustrated embodiment is merely an example, and is not a description to limit the technical scope of the present invention.

The block diagram of 1st Embodiment of this invention. The flowchart which shows the control of 1st Embodiment. The block diagram of 2nd Embodiment of this invention. The block diagram of the conventional power steering device for motor vehicles.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hydraulic pump 2 ... Steering gear box 3 ... Oil tank 4 ... On-off valve 5 ... Pressure regulating valve 6 ... Oil temperature detection means / oil temperature sensor 7 ... Buzzer 8. ..Warning light 9 ... Cooling heat exchanger / oil cooler 10 ... Control means / control unit L1 ... High pressure circuit L2 ... Low pressure circuit L3 ... Oil supply circuit Lb ... Bypass circuit

Claims (5)

  Power steering for automobiles having a hydraulic pump having a relief circuit, a steering gear box for converting hydraulic pressure into steering assist force, a high-pressure circuit communicating from the hydraulic pump to the gear box, and a low-pressure circuit communicating from the gear box to the hydraulic pump In the device, a bypass circuit that bypasses the gear box and communicates the high-pressure circuit and the low-pressure circuit is provided, and the bypass circuit is provided with an on-off valve and a flow rate adjustment device, and the oil temperature detection disposed on the high-pressure circuit side Means and a control means, and the control means is configured to perform control to switch the flow of the high-pressure circuit to the bypass circuit when the value detected by the oil temperature detection means exceeds a predetermined value. A power steering device for automobiles.   2. The power steering apparatus for an automobile according to claim 1, wherein the oil temperature detecting means is provided inside the hydraulic pump.   2. The power steering apparatus for an automobile according to claim 1, wherein the oil temperature detecting means is provided in the vicinity of the hydraulic pump in the high pressure circuit.   The power steering device for an automobile according to any one of claims 1 to 3, wherein the flow rate adjusting device is a pressure regulating valve, and a valve opening pressure of the pressure regulating valve is set lower than a relief pressure of the hydraulic pump.   Any one of claims 1 to 4, comprising warning means, wherein the control means is configured to perform control to activate the warning means when the value detected by the oil temperature detection means exceeds a predetermined value. Power steering device for cars.

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