JPS646326B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coolant temperature control device for an internal combustion engine, and particularly to one in which the control device is provided within a coolant passage.

Various coolant temperature control devices that control valve opening temperature according to the load of an internal combustion engine have been proposed in the past. FIG. 1 shows this type of control device disclosed in Japanese Utility Model Application Publication No. 54-142722, in which a wax-type thermostat 3 is installed between a water outlet 1 provided in the engine body and a water outlet housing 2. is being held. This thermostat 3 has a container-shaped temperature sensing part 4 and a piston 5 that slides up and down inside the temperature sensing part 4. The temperature sensing part 4 is filled with solid wax and elastic rubber. The head of the piston 5 is configured such that upward biasing force is suppressed by the operation of a control piece 6, which will be described later. Therefore, when the temperature of the engine coolant rises and the wax melts and expands, the resulting pressure causes the temperature sensing portion 4 to move as long as the head of the piston 5 is restrained by the control piece 6. is pushed downward. Reference numeral 7 denotes a valve member provided on the outside of the temperature sensing part 4. When the thermostat 3 is not activated, the valve member 7 is biased toward the fixed valve seat 9 by the spring force of the spring 8, thereby cooling the thermostat. Liquid passage 1
0 is closed.

The control piece 6 is a diaphragm device 11 for actuating the control piece.
The diaphragm device 11 is attached to the water outlet housing 2 via a seal member 13. The upper chamber of the diaphragm device divided into upper and lower parts by the diaphragm 12 is a negative pressure chamber 14,
The lower chamber is an atmospheric chamber 15 that communicates with the atmosphere. The negative pressure chamber 14 is connected to a negative pressure source such as an intake manifold (not shown) via a negative pressure delay valve 16, and the intake negative pressure is guided to the negative pressure chamber 14 according to engine load fluctuations. .

Reference numeral 17 denotes a stopper provided at the upper part of the negative pressure chamber 14, which restricts the upward movement of the control end 6A when it slides up and down along the inner surface of the guide member 18 of the thermostat 3. . 19 is a spring provided in the negative pressure chamber 14, and when the negative pressure introduced into the negative pressure chamber becomes small and approaches atmospheric pressure, the spring force causes the diaphragm 12 and the control piece 6 to move as shown in the figure. Return to position.

To explain the operation of the coolant temperature control device configured in this way, first, when the load is high, the suction negative pressure in the intake manifold is relatively small and the diaphragm 12 is biased downward as shown in the figure. The piece 6 remains approximately in the position shown in the figure. Therefore, when the coolant temperature rises and the wax in the temperature sensing part 4 melts and expands, the free end of the head of the piston 5 immediately comes into contact with the end 6A of the control piece 6, causing the attachment to try to extend upward. The force is restrained by the spring force of spring 19. Therefore, the temperature sensing part 4 of the thermostat 3 is connected to the spring 8.
The valve member 7 provided around the temperature sensing part 4 is pulled away from the valve seat 9 and opened. That is, when the engine is under high load, the valve is opened by the thermostat 3 at a relatively early stage when the coolant temperature rises, so the temperature of the coolant is relatively low at the time when the valve starts opening. The temperature is maintained at, for example, around 70°C.

Next, when the engine is under low load, a relatively large suction negative pressure is introduced into the negative pressure chamber 14, so that the control piece 6 is pulled upward together with the diaphragm 12 against the spring force of the spring 19. Therefore, when the wax in the temperature sensing part 4 expands due to a rise in coolant temperature, the piston 5 first begins to extend upward, but since the end 6A of the control piece 6 is pulled upward, the piston 5 Piston 5 continues to extend until its free end abuts end 6A. After the piston 5 comes into contact with the control piece 6, the valve is opened by the thermostat 3 in the same manner as described above. In other words, the temperature is kept relatively high compared to when the load is high.

However, in such a conventional internal combustion engine coolant temperature control device, the diaphragm device 11 is disposed outside the water outlet housing 2 and is connected to the thermostat 3 provided in the coolant passage 10 and the control device. They are connected via piece 6. Furthermore, a seal member 13 provided around the control piece 6 that slides up and down prevents the coolant in the coolant passage 10 from leaking to the outside.

As the control piece 6 slides in close contact with the seal member 13, the outer circumferential surface of the control piece 6 and the seal member 13 may wear out, causing coolant to leak to the outside, or The stick or friction force between the control piece 6 and the sealing member 13 makes the operation of the control piece 6 uncertain, making it difficult to act sensitively to changes in the suction negative pressure. Also,
Since the thermostat 3 cannot sufficiently control the coolant temperature, the fuel consumption rate in the low load region of the internal combustion engine cannot be sufficiently improved.

An object of the present invention is to provide a coolant temperature control device for an internal combustion engine, which eliminates the above-mentioned conventional drawbacks, enables accurate and reliable coolant temperature control, reduces the number of parts, and achieves reduction in size and weight. Our goal is to provide the following.

In order to achieve such an object, the present invention provides a thermostat that opens and closes a valve member by driving a valve member via a temperature sensing part depending on the coolant temperature in a coolant passage, and a thermostat that operates according to the operating state of an internal combustion engine. In the coolant temperature control device for an internal combustion engine, the control unit includes a bellows disposed in the coolant passage and displaces according to the operating state, and a control unit that controls the cooling temperature. Equipped with a control axis that controls the thermostat by transmitting
A control shaft is slidably fitted into a rubber member that isolates a temperature sensing part of a thermostat from a coolant passage, and displacement of the control shaft is limited and allowed between the rubber member and the end of the control shaft. It is characterized by the provision of space.

According to the present invention, the control section is disposed in the coolant passage together with the control shaft, and the tip of the control shaft is slidably fitted into the rubber member that keeps the temperature sensing section liquid-tight. By maintaining a space between the tip of the shaft and the rubber member, the control shaft does not immediately open the valve member even if the coolant temperature rises, especially at low loads. The valve opening temperature can be kept high, fuel consumption rate can be improved, and problems caused by coolant leakage and wear around the control shaft, which are conventional, can be eliminated.

Hereinafter, the present invention will be explained in detail based on the drawings.

2 and 3 show an embodiment of the present invention, with FIG. 2 showing a state under low load and FIG. 3 showing a state under high load. In FIG. 2, 21 is a thermostat held between a water outlet 22 and a water outlet housing 23, and this thermostat 21 is connected to a temperature sensing portion 24.
A control shaft 26 constituting an actuator as a control section 25 slides up and down inside the temperature sensing section 24 . Wax 28 is filled between the rubber member 27 fitted to one end of the control shaft 26 and the temperature sensing section main body 24A.

When the thermostat 21 is not activated, the valve member 2
9 comes into close contact with the valve seat 31 due to the spring force of the spring 30,
The coolant passage 32 is closed. The other end of the control shaft 26 is provided with a flange portion 33 having a surface perpendicular to the control shaft 26, and a stopper 35 connected to the negative pressure introduction pipe 34 and fixed to the water outlet housing 23. A spring 37 is interposed between the bellows 36 and the negative pressure chamber 38.
form. Further, 39 is a guide for guiding the control shaft 26, 39A is an end face of this guide 39, 40 is a space formed between the rubber member 27 and the control shaft 26, and 41 is a seal.

In the internal combustion engine coolant temperature control device configured as described above, when the coolant temperature reaches the wax melting point, the wax 28 melts and expands, causing the control shaft 26 to move upward via the rubber member 27. It tries to push up, but when the load is low, as shown in Figure 2,
The flange portion 33 is in contact with the stopper 35,
Furthermore, as shown in FIG. 3, even under high load when the flange portion 33 and the stopper 35 are spaced apart, the spring force of the spring 37 is set to a predetermined magnitude, so that the control shaft 26 is While being held in the position shown in FIG. 2 or 3, the thermostat 24 is pushed down in the direction shown in the figure, and the valve member 29 and the valve seat 31 are separated, and the thermostat 21 is activated. Open the valve.

That is, as shown in FIG. 2, when the engine is operating at a low load, the suction negative pressure in the negative pressure chamber increases, so the flange portion 33 of the control shaft 26
is displaced upward against the spring force of the spring 37, and a space 40 is created between the control shaft 26 and the rubber member 27 fitted to the control shaft 26.
Since this space 40 remains, even if the coolant temperature rises, the expansion of the wax 28 is absorbed into the space 40 via the rubber member 27, and no compressive force is transmitted to the control shaft 26. Therefore, the temperature of the coolant until the wax 28 expands and fills the space 40 is irrelevant to the control operation. That is, since the control shaft 26 is operated only when the wax 28 expands after the wax 28 has disappeared from the space 40, the valve opening temperature of the thermostat 21 can be set high.

Next, as shown in FIG. 3, when the engine is operating under high load, the suction negative pressure in the negative pressure chamber 38 decreases and approaches atmospheric pressure, so the flange portion 38
The end surface 39 of the guide 39 due to the spring force of the spring 37
It is displaced downward until it comes into contact with A. In this state, since the space 40 does not exist, when the coolant temperature rises and the wax 28 of the temperature sensing section 24 expands, this expansion force immediately acts as a force pushing up the control shaft 26. That is, when the load is high, the thermostat 21 opens in response to a rise in coolant temperature, so the opening temperature of the thermostat 21 can be lowered.

In the coolant temperature control device configured in this way, the control shaft 26 that controls the thermostat 21
Since the negative pressure chamber 38 and the negative pressure chamber 38 are provided in the coolant passage 32, there is no need for the seal member 13 provided to prevent coolant leakage as in the conventional example, and the connection between the seal member 13 and the control shaft 26 is eliminated. Since no friction or wear occurs between the two, the control shaft 26 can now operate reliably in response to the coolant temperature.

As explained above, according to the present invention, since the thermostat and the control section for controlling the valve opening temperature are provided in the coolant passage of the internal combustion engine,
The seal to prevent coolant leakage can be removed.
Uncertainty caused by coolant leakage and frictional force between the control shaft and the seal is eliminated, allowing accurate and reliable control of coolant temperature, effectively improving fuel consumption, especially in low load areas. be able to. Further, according to the present invention, since the coolant temperature control device is provided in the coolant passage, the number of components is reduced, which makes it possible to make the device smaller and lighter, which of course makes it less expensive. be.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a conventional coolant temperature control device, FIG. 2 is a block diagram showing an example of the coolant temperature control device of the present invention in a low load state, and FIG.
The figure is a configuration diagram showing the state under high load. DESCRIPTION OF SYMBOLS 1... Water outlet, 2... Water outlet housing, 3... Thermostat, 4... Temperature sensing part, 5... Piston, 6... Control piece, 6A... End, 7... Valve member , 8...spring,
9...Valve seat, 10...Cooling liquid passage, 11...Diaphragm device, 12...Diaphragm, 13...
Seal member, 14... Negative pressure chamber, 15... Atmospheric chamber,
16... Negative pressure delay valve, 17... Stopper, 18...
...Guide member, 19...Spring, 21...Thermostat, 22...Water outlet, 23...
... Water outlet housing, 24 ... Temperature sensing section, 24A ... Temperature sensing section main body, 25 ... Control section,
26...Control shaft, 27...Rubber member, 28...Wax, 29...Valve member, 30...Spring, 31...
... Valve seat, 32 ... Coolant passage, 33 ... Flange section, 34 ... Negative pressure introduction pipe, 35 ... Stopper, 3
6... Bellows, 37... Spring, 38... Negative pressure chamber, 39... Guide, 39A... End face, 40...
Space, 41...Seal.

Claims (1)

[Scope of Claims] 1. A thermostat that opens and closes a valve member by driving a valve member via a temperature sensing part according to the temperature of the coolant in the coolant passage, and controlling the thermostat according to the operating state of the internal combustion engine; A coolant temperature control device for an internal combustion engine, comprising: a control section that controls the cooling temperature; a control shaft that controls the thermostat by transmitting displacement; the control shaft is slidably fitted into a rubber member that isolates a temperature sensing portion of the thermostat from the coolant passage; and the rubber member A coolant temperature control device for an internal combustion engine, characterized in that a space for limiting and allowing displacement of the control shaft is provided between the control shaft and the end of the control shaft.