JPH0526211A - Heat generation preventive mechanism for hydraulic circuit - Google Patents

Abstract

PURPOSE:To suppress heat generation of operation oil when failure occurs at a hydraulic circuit such as a hydraulic pump abnormality, in the hydraulic circuit having a hydraulic device operated unrelatedly to the movement of a vehicle. CONSTITUTION:A bypass pipeline 17 is arranged parallelly to a control valve 2 of an engine cooling hydraulic fan 3, while a check valve 5 is arranged on the bypass pipeline 17. When a system line pressure is increased at the time of failure of a variable volume pump 1, the check valve 5 is opened and a rotational number of the hydraulic fan 3 is increased. Thus, a relief flow rate from a relief valve 4 is reduced and heat generation of operation oil is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat generation prevention mechanism for preventing heat generation in a hydraulic circuit for a vehicle due to a failure.

[0002]

2. Description of the Related Art There are hydraulic devices which are not used for controlling the behavior of a vehicle but are operated independently of the behavior of the vehicle. An example of this hydraulic device is an engine cooling hydraulic fan driven by hydraulic pressure.

FIG. 6 shows an example of a hydraulic circuit having the above-described engine cooling hydraulic fan. 1 is a variable displacement pump, 12 is a reservoir tank, 14 is a hydraulic oil supply pipe, 1
Reference numeral 5 is a hydraulic oil return pipe, and 4 is a relief valve. And
Reference numeral 3 is an engine cooling hydraulic fan, and 2 is a control valve for the hydraulic fan 3.

In the hydraulic circuit shown in FIG. 6, the hydraulic fan 3 is subjected to flow rate match control or power match control by the variable displacement pump 1. When such control is performed, the variable displacement pump 1 does not discharge an excessive flow rate.

Therefore, there is no relief flow rate from the relief valve 4, and it is not necessary to install an oil cooler for preventing heat generation in the hydraulic circuit of FIG.

On the other hand, as a hydraulic pump, there is a hydraulic circuit using a fixed displacement pump instead of the variable displacement pump as shown in FIG.

FIG. 7 shows a hydraulic circuit using the fixed displacement pump 8 described above, and the same members as those in the example of FIG. 6 are designated by the same reference numerals.

In FIG. 7, 9 is an oil cooler and 10 is an oil cooler fan driven by a drive motor M. In the example of FIG. 7, since the discharge capacity of the fixed capacity pump 8 cannot be adjusted, the discharge hydraulic oil of the pump 8 is constantly drained from the relief valve 4 so that the pressure of the hydraulic oil can be adjusted. I try to keep it constant. Therefore, since the hydraulic oil generates heat due to the flow resistance of the relief valve 4, the oil cooler 9 radiates heat.

As hydraulic devices that are operated regardless of the behavior of the vehicle, there are hydraulic auxiliary machines for driving an air conditioner in addition to the engine cooling hydraulic fan described above.

[0010]

However, in the conventional hydraulic circuit shown in FIG. 6, in the case where the line pressure becomes high due to an abnormality of the variable displacement pump 1, the relief valve 4 is provided.
Therefore, the working oil is returned to the working oil return pipe 15 on the low pressure side. In this case, there is a problem that the relief valve 4 heats the hydraulic oil to raise the oil temperature and adversely affect the hydraulic circuit.

On the other hand, in the hydraulic circuit using the fixed displacement pump 8 shown in FIG. 7, since the pump flow rate is fixed, the relief amount does not increase under the influence of the pump 8. However, since the hydraulic oil discharged from the pump 8 is constantly drained from the relief valve 4, when the oil cooler fan 10 fails, the hydraulic oil is heated by the relief valve 4, the oil temperature rises, and the hydraulic pressure increases. There is a problem that it adversely affects the circuit.

[0012]

SUMMARY OF THE INVENTION In order to solve the above problems, the invention according to claim 1 is directed to a hydraulic device which is operated independently of the behavior of a vehicle, and a hydraulic pump which supplies hydraulic oil to the hydraulic device. And a relief valve which is arranged between the hydraulic pump and the hydraulic device and which opens when the pressure of the hydraulic oil is equal to or higher than a first predetermined value. When the pressure of the hydraulic oil is equal to or higher than the second predetermined value,
It is characterized in that a supply amount increasing means for decreasing the relief flow rate from the relief valve by increasing the supply amount of hydraulic oil from the hydraulic pump to the hydraulic device is provided.

According to the second aspect of the present invention, there is provided a hydraulic device that is operated regardless of the behavior of the vehicle, a hydraulic pump that supplies hydraulic oil to the hydraulic device, and a hydraulic pump and the hydraulic device. A heat generation preventing mechanism for a hydraulic circuit having a relief valve that is arranged between the hydraulic oil and the relief valve, which opens when the pressure of the hydraulic oil is equal to or higher than a predetermined value. The present invention is characterized by including a supply amount increasing means for decreasing the relief flow rate from the relief valve by increasing the supply amount of hydraulic oil from the hydraulic pump to the hydraulic device.

Further, in the invention according to claim 3, the hydraulic device which is operated regardless of the behavior of the vehicle, the hydraulic pump which supplies hydraulic oil to the hydraulic device, and the hydraulic pump and the hydraulic device. A heat generation prevention mechanism for a hydraulic circuit having a relief valve that is arranged between the relief valve and is opened when the pressure of the hydraulic oil is equal to or higher than a predetermined value, and an oil cooler fan that cools the hydraulic oil from the relief valve. When the oil cooler fan is out of order, the supply amount increasing means for decreasing the relief flow rate from the relief valve by increasing the operation oil supply amount from the hydraulic pump to the hydraulic device is provided.

[0015]

In the invention according to claim 1, when the system line pressure becomes equal to or higher than the second predetermined value due to the failure of the hydraulic pump, the supply amount increasing means increases the amount of hydraulic oil supplied from the hydraulic pump to the hydraulic device. To be done. As a result, the relief flow rate from the relief valve is reduced, and heat generation of the hydraulic oil is prevented.

Further, in the invention according to claim 2,
When the temperature of the hydraulic oil becomes equal to or higher than a predetermined temperature due to the failure of the hydraulic pump, the supply amount increasing means increases the hydraulic oil supply amount from the hydraulic pump to the hydraulic device. As a result, the relief flow rate from the relief valve is reduced, and heat generation of the hydraulic oil is prevented.

Further, in the invention according to claim 3, when the oil cooler fan fails, the supply amount increasing means increases the supply amount of hydraulic oil from the hydraulic pump to the hydraulic device. As a result, the relief flow rate from the relief valve is reduced, and heat generation of the hydraulic oil is prevented.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a hydraulic circuit of an embodiment of the invention according to claim 1, and the same members as those in the example of FIG. 6 are designated by the same reference numerals. The example of FIG. 1 is a composite hydraulic circuit in which an engine cooling hydraulic fan system and a hydraulic suspension system 13 are combined. This composite hydraulic circuit is a hydraulic circuit that shares a hydraulic pressure source of a plurality of hydraulic systems, and is advantageous for energy saving and vehicle weight reduction.

In FIG. 1, 5 is a check valve (supply amount increasing means), and this check valve 5 is provided in a bypass pipe 17 arranged in parallel with the control valve 2. The cracking pressure of the check valve 5 is set to an intermediate value between the system maximum control pressure and the relief pressure of the relief valve 4.

When the line pressure rises due to the abnormality of the variable displacement pump 1, the check valve 5 is opened and the hydraulic fan 3 is rotated regardless of the opening degree of the control valve 2. As a result, the relief flow rate from the relief valve 4 is reduced, so that the relief valve 4 is prevented from generating heat and the adverse effect on the hydraulic circuit is avoided.

FIG. 2 shows a hydraulic circuit of another embodiment of the invention according to claim 1, and the members equivalent to those of the example of FIG. 1 are designated by the same reference numerals.

In FIG. 2, 6 is a pressure switch for detecting the system line pressure, and 16 is a controller of the control valve 2. The pressure switch 6, the controller 16 and the control valve 2 constitute a supply amount increasing means.

When the line pressure rises due to an abnormality of the variable displacement pump 1, the pressure switch 6 is turned on, and the turned-on signal is supplied to the controller 16. Then, the controller 16 supplies a signal to the control valve 2 so that the opening degree of the control valve 2 becomes the maximum, and the hydraulic fan 3 becomes the maximum rotation. As a result, as in the example of FIG. 1, the relief flow rate from the relief valve 4 becomes small, so that heat generation of the hydraulic oil is prevented and adverse effects on the hydraulic circuit are avoided.

FIG. 3 shows a hydraulic circuit according to an embodiment of the invention as claimed in claim 2, and the same members as those in the example of FIG. 2 are designated by the same reference numerals.

In FIG. 3, numeral 7 is a temperature sensor which is arranged near the relief valve 4 and detects the temperature of the hydraulic oil. The temperature sensor 7, the control valve 2, and the controller 16 constitute a supply amount increasing means.

When the line pressure rises due to an abnormality of the variable displacement pump 1 and the temperature of the hydraulic oil exceeds a predetermined value, the temperature sensor 7
A signal indicating an oil temperature abnormality is supplied from the controller 16 to the controller 16. Then, the controller 16 supplies a signal to the control valve 2 so that the opening degree of the control valve 2 becomes the maximum, and the hydraulic fan 3 becomes the maximum rotation. As a result, as in the example of FIG. 2, heat generation of the hydraulic oil is prevented, and adverse effects on the hydraulic circuit are avoided.

FIG. 4 shows a hydraulic circuit of another embodiment of the invention according to claim 2, and the same members as those of the example of FIG. 3 are designated by the same reference numerals. The example of FIG. 4 is an example when applied to a complex hydraulic circuit using a fixed displacement pump 8, an oil cooler 9, and an oil cooler fan 10 driven by a drive motor M.

In the example of FIG. 4, the oil cooler fan 1
When 0 has failed and the hydraulic oil has exceeded a predetermined value, the control valve 2 reaches the maximum opening and the hydraulic fan 3 reaches the maximum rotation. As a result, as in the example of FIG. 3, heat generation of the hydraulic oil is prevented,
The adverse effect on the hydraulic circuit is avoided.

FIG. 5 shows a hydraulic circuit of an embodiment of the invention according to claim 3, and the same members as those in the example of FIG. 4 are designated by the same reference numerals. In the case of the example of FIG. 5, the drive motor M
A rotation sensor 11 for detecting the number of rotations of
A rotation speed detection signal is supplied from the rotation sensor 11 to the controller 16. The rotation sensor 11, the control valve 2, and the controller 16 constitute a supply amount increasing means.

In the example of FIG. 5, the oil cooler fan 1
When 0 fails and the rotation speed of the motor M becomes equal to or lower than a predetermined rotation speed, the controller 16 sets the control valve 2 to the maximum opening degree and the hydraulic fan 3 is set to the maximum rotation speed. This allows
As in the example of FIG. 4, heat generation of the hydraulic oil is prevented, and adverse effects on the hydraulic circuit are avoided.

In addition to the effects described above, each of the above-described embodiments has the following effects.

That is, when the variable displacement pump 1 fails or the oil cooler fan 10 fails, the rotational speed of the engine cooling hydraulic fan 3 is increased, so that the cooling capacity of the hydraulic pipes and the like around the engine is also improved. There is an effect.

Although the above-described embodiments are examples in which the present invention is applied to the composite hydraulic circuit, the hydraulic device is not a composite hydraulic circuit but a hydraulic device alone operated independently of the behavior of the vehicle. It can also be applied to a pressure circuit.

Further, in the case of the composite hydraulic circuit, the other hydraulic device combined with the hydraulic device which is operated regardless of the behavior of the vehicle is not the above-mentioned hydraulic suspension device but for four-wheel steering. It may be a hydraulic actuator device, a four-wheel drive hydraulic actuator device, or the like.

[0035]

As described above, according to the invention of claim 1, a hydraulic device which is operated independently of the behavior of the vehicle,
A hydraulic pump that supplies hydraulic fluid to the hydraulic device and a relief valve that is arranged between the hydraulic pump and the hydraulic device and that opens when the pressure of the hydraulic fluid is equal to or higher than a first predetermined value. A mechanism for preventing heat generation of a hydraulic circuit that has, wherein when the pressure of the hydraulic oil is equal to or higher than a second predetermined value, the amount of hydraulic oil supplied from the hydraulic pump to the hydraulic device is increased so that Since the supply amount increasing means for reducing the relief flow rate is provided, heat generation of the hydraulic oil by the relief valve is prevented when the hydraulic circuit is abnormal, and the adverse effect on the hydraulic circuit is avoided.

According to the second aspect of the invention, when the temperature of the hydraulic oil is equal to or higher than the predetermined temperature, the amount of hydraulic oil supplied to the hydraulic device is increased to reduce the relief flow rate from the relief valve. Since the supply amount increasing means is provided, the same effect as the invention according to claim 1 can be obtained.

Further, according to the invention of claim 3,
The invention according to claim 1, further comprising a supply amount increasing means for decreasing the relief flow rate from the relief valve by increasing the operation oil supply amount from the hydraulic pump to the hydraulic device when the oil cooler fan fails. The same effect as can be obtained.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of an embodiment of the invention according to claim 1;

FIG. 2 is a hydraulic circuit diagram of another embodiment of the invention according to claim 1;

FIG. 3 is a hydraulic circuit diagram of an embodiment of the invention according to claim 2;

FIG. 4 is a hydraulic circuit diagram of another embodiment of the invention according to claim 2;

FIG. 5 is a hydraulic circuit diagram of an embodiment of the invention according to claim 3;

FIG. 6 is a diagram showing an example of a conventional hydraulic circuit.

FIG. 7 is a diagram showing another example of a conventional hydraulic circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Variable capacity pump, 2 ... Control valve, 3 ... Engine cooling hydraulic pump, 4 ... Relief valve, 5 ... Check valve, 6 ... Pressure switch, 7 ... Temperature sensor, 8 ... Fixed capacity pump, 9
... oil cooler, 10 ... oil cooler fan, 11 ... rotation sensor, 12 ... reservoir tank, 14 ... hydraulic oil supply pipe, 15 ... hydraulic oil return pipe, 16 ... controller, 17
… Bypass piping.

Claims (3)

[Claims] 1. A hydraulic device that operates regardless of vehicle behavior, and a hydraulic pump that supplies hydraulic oil to the hydraulic device.
A heat generation preventing mechanism for a hydraulic circuit, which is arranged between the hydraulic pump and the hydraulic device, and has a relief valve that opens when the pressure of the hydraulic oil is equal to or higher than a first predetermined value. A supply amount increasing means for decreasing the relief flow rate from the relief valve by increasing the supply amount of hydraulic oil from the hydraulic pump to the hydraulic device when the oil pressure is equal to or higher than a second predetermined value. A mechanism to prevent heat generation in the hydraulic circuit. 2. A hydraulic device that operates regardless of the behavior of the vehicle, and a hydraulic pump that supplies hydraulic oil to the hydraulic device.
A heat generation preventing mechanism for a hydraulic circuit having a relief valve which is arranged between the hydraulic pump and the hydraulic device and which opens when the pressure of the hydraulic oil exceeds a predetermined value. Is above a predetermined temperature, the hydraulic pressure is provided with a supply amount increasing means for decreasing the relief flow rate from the relief valve by increasing the hydraulic oil supply amount from the hydraulic pump to the hydraulic device. Circuit heat generation prevention mechanism. 3. A hydraulic device that operates regardless of the behavior of the vehicle, and a hydraulic pump that supplies hydraulic oil to the hydraulic device.
A relief valve which is arranged between the hydraulic pump and the hydraulic device, and which opens when the pressure of the hydraulic oil is a predetermined value or more,
A heat generation prevention mechanism for a hydraulic circuit having an oil cooler fan for cooling the hydraulic oil from the relief valve, which increases the amount of hydraulic oil supplied from the hydraulic pump to the hydraulic device when the oil cooler fan fails. A heat generation preventing mechanism for a hydraulic circuit, characterized by comprising a supply amount increasing means for decreasing the relief flow rate from the relief valve.