JPH0444814Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a rotational speed control device for a cooling fan of an internal combustion engine used in vehicles such as automobiles, and particularly relates to a rotational speed control device for a hydraulically driven cooling fan. .

Conventional technology In internal combustion engines used in vehicles such as automobiles,
The cooling fan is driven by a hydraulic motor such as a hydraulic motor, and the flow rate of working fluid supplied to the hydraulic motor is controlled according to the temperature of the cooling water of the internal combustion engine, so that the rotational speed of the cooling fan is controlled by the cooling water. Control according to temperature has been proposed in the past, for example, in Japanese Utility Model Publication No. 49-40183 and Japanese Unexamined Patent Application Publication No. 49-40183
58-13119.

Problems to be solved by the invention In the hydraulically driven cooling fan as described above,
When the temperature of the working fluid supplied to the hydraulic motor changes, the volumetric efficiency of the pump and the hydraulic motor changes, and therefore the flow rate of the working fluid supplied to the hydraulic motor is controlled according to the cooling water temperature. However, the fan rotation speed is not stable, especially when the liquid temperature is low, the fan rotation speed becomes higher than the required rotation speed, and the cooling fan rotates at an unnecessarily high speed, resulting in a disadvantage in terms of fan noise. If the liquid is supplied to the hydraulic motor at the same flow rate as when the liquid temperature is high, the load on the pump increases due to the large pressure loss in the working liquid conduit.

The object of the present invention is to provide an improved rotational speed control in a hydraulically driven cooling fan that solves the above-mentioned problems.

Means for Solving the Problems According to the present invention, the above object is to provide a water temperature sensor for detecting the temperature of cooling water of an internal combustion engine, which is a rotational speed control device for a cooling fan rotationally driven by a hydraulic motor. a liquid temperature sensor that detects the temperature of the working liquid of the hydraulic motor; and an increase in the cooling water temperature in response to the cooling water temperature detected by the water temperature sensor and the working liquid temperature detected by the liquid temperature sensor. The flow rate of the working fluid supplied to the hydraulic motor is increased in accordance with the flow rate, and when the working fluid temperature is below a predetermined value, the flow rate of the working fluid supplied to the hydraulic motor is increased compared to when the working fluid temperature is above a predetermined value. This is achieved by a cooling fan rotation speed control device having a flow rate control device that reduces the flow rate of the working liquid relative to the cooling water temperature.

Effects and Effects of the Invention According to the above-described configuration, the flow rate of the working fluid supplied to the hydraulic motor changes depending on the temperature of the working fluid, and when the temperature of the working fluid is low, the flow rate of the working fluid to the hydraulic motor is lower than when the temperature is high. The flow rate of the supplied working liquid is reduced, and as a result, when the liquid temperature is low, the fan rotation speed is set lower than when the liquid temperature is high, and the blower fan is prevented from rotating more than necessary when the liquid temperature is low. At the same time, the pump load is reduced and an increase in auxiliary loss is avoided. When the temperature of the working liquid is below a predetermined value, the outside air temperature is generally low and the heat exchange efficiency of the radiator is high, so even if the cooling fan rotation speed is set lower than when the liquid temperature is high, cooling will continue. Water is sufficiently cooled.

Embodiments Hereinafter, the present invention will be described in detail with reference to embodiments with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a hydraulically driven cooling fan with a speed control device according to the present invention. In FIG. 1, reference numeral 10 indicates a cooling fan that supplies cooling air to a radiator 52 of an internal combustion engine 50, and the cooling fan 10 is rotationally driven by a hydraulic motor 12.

Hydraulic motor 12 has its working fluid inlet connected to conduit 14.
The pump 16 is connected to a pump 16 by a conduit 18, and the working liquid is fed under pressure from the pump 16. The pump 16 is connected to a reserve tank 20 by a conduit 18, from which the working liquid is sucked. ing. The pump 16 has a built-in relief valve, and the pressure of the working fluid discharged by the pump 16 is controlled to be below a predetermined constant value.

The hydraulic motor 12 has a working fluid outlet connected to the reserve tank 20 by a conduit 22 to discharge the working fluid into the reserve tank 20 .

Conduits 14 and 18 are connected by a bypass conduit 24 having a flow control valve 26 in the middle.
The flow rate control valve 26 is an electromagnetically actuated flow rate control valve that operates based on a control signal from the control device 30 to control the flow rate of the working liquid flowing through the bypass conduit 24 and supplied to the hydraulic motor 12. It is adapted to control the flow rate of the working fluid.

In this embodiment, the flow control valve 26 reduces the flow rate of the working fluid flowing through the bypass conduit 24 in response to an increase in the duty ratio of the pulse signal applied thereto, thereby reducing the flow rate of the working fluid supplied to the hydraulic motor 12. The flow rate is increasing.

The radiator 52 is equipped with a water temperature sensor 32 that detects the temperature of the cooling water of the internal combustion engine 50, and the reserve tank 22 is equipped with a liquid temperature switch 34 that detects whether the temperature of the working fluid is below a predetermined value, for example, 20°C. The water temperature sensor 32 provides information regarding the cooling water temperature, and the liquid temperature switch 34 provides information regarding whether the operating fluid temperature is below a predetermined value to the control device 30.

The control device 30 is an electric type including a microcomputer with a general structure, and includes a water temperature sensor 3.
Cooling water temperature detected by 2 and liquid temperature switch 3
A duty ratio is calculated depending on whether or not the working fluid temperature detected by 4 is below a predetermined value, and a pulse signal of this duty ratio is output to the flow rate control valve 26. This duty ratio is determined so that it increases as the cooling water temperature rises, and decreases when the working fluid temperature is below a predetermined value compared to when it is above a predetermined value.

In the embodiment shown in FIG. 2, the water temperature sensor 32 is composed of a thermistor whose electrical resistance value decreases as the sensed temperature rises, and the water temperature sensor 32 and one electrical resistance element 36 are mutually connected. A liquid temperature switch 34 is connected in series and in parallel with the electric resistance element 36, and the liquid temperature switch 34 is opened when the working liquid temperature is below a predetermined value, and closed when the working liquid temperature is above the predetermined value. It is starting to become a reality.

Therefore, the electrical resistance value R of the electrical circuit as described above
The liquid temperature switch 3 is activated when the operating liquid temperature is below a predetermined value.
4 is open, the combined value of the electrical resistance value Rw of the water temperature sensor 32 and the electrical resistance value _R1 of the electrical resistance element 36 is Rw + R _1. On the other hand, when the temperature of the operating fluid exceeds a predetermined value, the temperature-sensitive switch 34 closes. When it is, the value is equal to the electrical resistance value Rw of the water temperature sensor 32. The control device 30 is configured to output a pulse signal with a duty ratio that increases as the electrical resistance value R decreases, so that the duty ratio increases as the cooling water temperature increases and when the working fluid is below a predetermined value. At some times, it becomes smaller by a value corresponding to the electrical resistance value R ₁ of the electrical resistance element 36 compared to when it is above a predetermined value.

By controlling the duty ratio as described above, the flow rate of the working fluid supplied to the hydraulic motor 12 increases as the cooling water temperature rises, and when the working fluid temperature is below a predetermined value, the flow rate of the working fluid supplied to the hydraulic motor 12 increases to the predetermined value. By controlling the flow rate of the working fluid supplied to the hydraulic motor 12 in this way, the rotational speed of the cooling fan 10 decreases as shown in FIG. 3. It increases as the cooling water temperature rises, and when the liquid temperature switch 34 is open, that is, when the working liquid temperature is below a predetermined value, and when the working liquid temperature is above a certain value, that is, the liquid temperature switch 34 is open. Reduced compared to when closed.

In the above, the present invention has been described in detail with respect to a specific embodiment, but the present invention is not limited to this, and various other embodiments are possible within the scope of the present invention. This will be clear to those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of a hydraulically driven cooling fan equipped with a rotation speed control device according to the present invention, and FIG. 2 is an embodiment of the temperature detection portion of the rotation speed control device according to the present invention. An electric circuit diagram showing an example, and FIG. 3 is a graph showing control characteristics of fan rotation speed. 10... Cooling fan, 12... Hydraulic motor, 1
4... Conduit, 16... Pump, 18... Conduit, 2
0... Reserve tank, 22... Conduit, 24...
Bypass conduit, 26...flow control valve, 30...control device, 32...water temperature sensor, 34...liquid temperature switch, 36...electric resistance element, 50...internal combustion engine, 52...radiator.

Claims (1)

[Scope of utility model registration request] A rotation speed control device for a cooling fan rotatably driven by a hydraulic motor, comprising: a water temperature sensor for detecting the temperature of cooling water of an internal combustion engine; a liquid temperature sensor for detecting the temperature of a working fluid of the hydraulic motor; In response to the cooling water temperature detected by the water temperature sensor and the working liquid temperature detected by the liquid temperature sensor, the flow rate of the working liquid supplied to the hydraulic motor is increased in accordance with the increase in the cooling water temperature, and the working liquid is increased. a flow rate control device that reduces the flow rate of the working liquid with respect to the temperature of the cooling water supplied to the hydraulic motor when the temperature is below a predetermined value, compared to when the temperature of the working liquid is above a predetermined value; Rotation speed control device.