JP3203360B2 - Automotive engine cooling system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling system for an automobile engine.

[0002]

2. Description of the Related Art The operating range of a thermostat used in an engine cooling system has a valve lift-up speed of up to 87.degree. C., which is a state change state where all wax is solidified and liquefied, and a valve lift-up speed. Above 87 ° C in the body expansion area of the small wax liquid,
The upper limit of the water temperature is as high as 123 ° C.

[0003]

The operating temperature range of the thermostat is concentrated within a large state change region of 87 ° C. where the lift-up speed of the valve at which the wax liquefies is liquefied, and the valve is lifted up in that region. In addition to taking measures to expand and increase the temperature, the upper limit of the water temperature is suppressed to 81 ° C. or lower by interlocking the cooling fan switch.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a valve lift valve.
The means for expanding and increasing the length of the rod is achieved by first reducing the thickness of the side wall of the center hole of the elastic seal spool, which engages with the rod, within a range of 25% to 5% of the diameter of the rod. In order to reduce the sliding friction of the spool by reducing the lubricating oil pressure and the outer wax pressure to zero, and to reduce the wax pressure to squeeze the spool, and secondly, at least one small hole is formed in the flange of the thermostat. The purpose is to make the water pressure applied to the front and back of the main valve the same, reduce the spring constant of the return spring, and promote the liquefaction of the wax. By combining the first and second synergistic effects and the cooling fan switch, the upper limit of the water temperature is suppressed to 81 ° C. or less, and the flow rate of the cooling water is doubled at 50% of its own capacity.

[0005] For example, the cooling fan switch is set to be turned on at a water temperature of 81 ° C. Since the flow rate of the cooling water passing through the main valve of the present invention is twice that of the conventional one, the water temperature drops extremely sensitively when the cooling fan switch is ON, so that the water temperature does not exceed 81 ° C. Therefore, the starting temperature of the cooling fan switch precedes. The upper limit of the water temperature is not always 81 ° C. Since it is better to lower the temperature even at 1 ° C, the starting temperature of the cooling fan switch should be lowered by 1 ° C and checked. This is the easiest, safest and quickest time.

【Example】

FIG. 2 shows a conventional wax type thermostat Y.
5 is a diagram of a cooling water temperature versus a main valve lift, respectively, for the wax type thermostat X of the present invention.

In any of the thermostats, the main valve starts to open at 72 ° C., but at X, the set temperature is 81 ° C., and the lift is 6 mm, but the margin is sufficient. 12 mm. That is, the set temperature of 81 ° C. is 50% of the self-capacity and achieves twice the result of the conventional one, and still saves a margin of 50% (lift 6 mm).
This is because turning on at 1 ° C. stops the rise in water temperature. If there is no cooling fan switch, X is greatly lifted and dangerous. The thermostat of the present invention cannot exist alone without the interlocking of the cooling fan switch of the present invention.

On the other hand, Y has a water temperature of 123 ° C. when the lift reaches 12 mm due to the continuous shortage of the lift under a wax liquid having a water temperature of 86 ° C. or more, but there is no room at all.

[0009] The X and Y curves and the Z-
The hatched portion between the line Z 'and the line X' is the difference between the flow rates of X and Y flowing through the main valve. At this time, the lift of X is 6 mm and the lift of Y is 3 mm. Therefore, the flow rate of X is about twice that of Y. By turning on the cooling fan switch, the first and second synergistic effects can exert such power. Therefore, the cooling fan, the cooling fan switch, and the fan motor including the radiator should be installed independently as one set so as not to be affected by others (within the dashed line in FIG. 12). . A radiator for an air conditioner, a fan, and the like are separately provided small.

FIGS. 3 and 4 are cross-sectional views of a wax-type thermostat for controlling the temperature of cooling water in an automobile engine cooling system according to the present invention, wherein the former shows the main valve closed and the latter shows its fully opened state.

In FIG. 3, a thermo-actuator 2 mounted on a wax type thermostat 1 is airtightly engaged with a rod 3 and a guide member 4 slidably engaged with the rod 3 and a lower end surface of the guide member 4. A required amount of lubricating oil 6 is sealed in a space formed between the inner bottom surface of the elastic seal spool 5 and the lower end surface of the rod, which also slidably engages with the rod 3. Are inserted into a heat-sensitive cylinder 8 filled with a wax 7 and hermetically pressed.

Generally, as shown in FIG. 4, a wax type thermostat comprises a frame 11 fixed to a housing 10 forming a valve seat 9, a main valve 12 engaged with the valve seat 9, and a thermoactuator press-fitting and fixing the same. 2 and main valve 1
A return spring 13 interposed between the frame 2 and the frame 11.

When the water temperature rises above the specified temperature, the lubricating oil 6 in the elastic seal spool 5 equivalent to the wax pressure due to the melt expansion of the wax 7 sealingly filling the thermosensitive cylinder 8 of the thermoactuator 2 The rod 3 is squeezed upward against the return spring 13. However, since the rod 3 is engaged and supported by the vertex 14 of the housing 10, the main valve 12 relatively opens downward (FIG. 4).

When the water temperature falls, the molten wax 7 in the heat-sensitive cylinder 8 gradually solidifies and contracts, so that the main valve 12 is fully closed by the return spring 13 (FIG. 3). In this way, the guide member 4 of the thermoactuator 2 slides up and down with respect to the rod 3 engaged and supported on the vertex 14 of the housing 10, and the main valve 12 fixed to this.
And the bypass valve 15 integrated with the main valve opens and closes accordingly.

The synergistic effect of reducing the thickness of the elastic seal spool and providing a small hole in the flange surface to reduce the spring constant of the return spring to す る will be described below.

FIG. 1 shows a simple bench test apparatus of the hydraulic pressure of the elastic seal spool and the main valve lift using the hydraulic pressure instead of the wax pressure. 35. Hydraulic supply port 36. 37. Cut and mount the thermal cylinder so that the elastic seal spool inside the thermo actuator can be observed. Window for observing inside from outside 38. Transparent acrylic pipe 39. Elastic seal spool 40. Rod 41. Lubricating oil 42. Return spring 43. Dial indicator (not shown)

Table 1 shows the actual measured values of the hydraulic pressure and the valve lift measured by the test apparatus shown in FIG. In Table 1, (A) shows a conventional rod 3 having a diameter of 3.8 mm, a seal spool having a wall thickness of 1.7 mm, 45% of the diameter, and a spring constant of 15.1 kg. (C) is a rod 3 having a diameter of 4.5 mm and a thickness of 1.25 mm of 25% of that diameter, and (C) having a diameter of 0.225 mm of 5% of that diameter. The spring constant of the combined return spring 9 is 0.55 kg / mm.

When the thickness of the elastic seal spool 5 is extremely thin as shown in FIG. 3C, the pressure of the lubricating oil 6 inside the spool becomes equivalent to the wax pressure. Since the elastic seal spool 5 is supported by an equivalent pressure from the inside and outside thereof and floats, the frictional resistance between the rods 3 becomes zero, and the lift up of the rod 3 is performed by the lubricating oil 6 applied to the lower end surface of the rod 3. Induced by pressure. And since the frictional resistance is zero, the main valve opens rapidly at low wax pressure.

(A) has a wall thickness of 1.7 mm, the starting pressure is 80 kg / cm ² , the lift is 0.6 mm, it resists a spring load of 15.1 kg, and 140 kg / cm is required to squeeze the rod 3 by 10 mm. It requires a pressure of cm ² and is out of the question.

The pressure for starting the rod 3 is (B), (C)
Both were 50 kg / cm ² , and the lift at that time was also 0.1 kg.
Although it is 4 mm, after that, the rod is squeezed up by 10 mm against the spring load of 15.1 kg, but (C) reaches 90 kg / cm ² because the ultra-thin wall is 0.225 mm,
(B) is delayed and reaches 100 kg / cm ² .

Therefore, considering these, the elastic seal
If the thickness of the spool 5 is increased to (B) or more, the starting pressure exceeds 50 kg / cm ^2.
25% of the diameter. The thickness of the elastic seal spool 5 is sufficient to be 5% as shown in FIG.
Since the manufacture becomes difficult and the cost increases, the upper limit of the wall thickness is set to 5% of the diameter of the rod 3.

Further, the spring constant of the return spring 9 of Table 1 (C) 0.55 kg / mm is changed to 0.27 kg / m.
Table 2 shows the experimental value (D) of the hydraulic pressure-main valve lift measured by the test apparatus of FIG.

[0023] (D) the start pressure 30kg / cm ² in the valve lift 0.3 mm, pressure 60 kg / cm ² in the valve lift 1
It becomes 3.5 mm. Ultra-thin elastic seal spool 5
In addition, the conventional spring constant is 0.55 kg / mm and 0.2
The synergistic effect of engaging the return spring 9 halved to about 7 kg / mm to promote the liquefaction of the wax 7 and rapidly increasing the amount of liquefaction to increase the valve lift is outstanding as shown in FIG. It is.

Conventionally, the flange 16 of the thermostat 1 of the automobile engine has always been provided with a known jiggle valve mechanism 17 for the purpose of accelerating the temperature rise of the cooling water of the engine.
(Fig. 5) is attached. During operation of the engine, the valve is closed by water pressure, and when the engine is stopped, the jiggle valve 18 is released and opened, so that cooling water can be supplied in the direction of the arrow.

However, this jiggle valve mechanism is actually the source of various evils as described later. This will be described below.

FIG. 6 shows an example of a conventional automobile engine cooling system having an old wax type thermostat configuration with a jiggle valve mechanism (not shown). Outlet 21 of engine water jacket 20 and Inlet 2 of radiator 22
A first water passage 24 between the first water passage 20 and a radiator outlet 25, a thermostat cap 26, a thermostat housing 27, and a water pump 28 to an inlet 29 of the water jacket 20; A bypass channel 31 communicating between the second channel 30 and the second channel 30;
And a bypass type thermostat 1 having a bypass valve 15 for opening and closing the opening 32 of the bypass channel 31 and a main valve 12 for opening and closing the second channel, the thermostat cap 26
Thereby, it is hermetically fixed in the thermostat housing 27.

In the figures, A 'is inside the thermostat housing 27 and B' is the thermostat cap 26
A measurement point of the water temperature of a portion near the inside, C is a measurement point of the flow rate, and 33 is a cooling fan.

When the engine is cold, the main valve 12 of the bypass thermostat 1 is closed and a jiggle valve 18 (not shown) is provided.
Is also closed by water pressure, so water jacket 20
The high-temperature cooling water from the outlet 21 cannot return to the inside of the radiator 22, and the bypass water passage 31 → the thermostat housing 27 → the water
The pump 28 is short-circuited and recirculated to the inlet 29 of the water jacket 20 as shown by the arrow. Therefore, the water temperature in the thermostat housing 27 rises quickly.

However, the radiator 22 and the thermostat
Since the cooling water between the caps 26 stays without flowing, the rise rate of the water temperature is low. As is clear from FIG. 7 of the self-recording record of FIG. 6, even if the water temperature A at the measurement point A ′ in the thermostat housing 27 becomes 87 ° C. of the valve opening temperature of the main valve 12 of the bypass type thermostat 1, the second water passage The water temperature B at the illustrated measurement point B ′ of 30 is only 45 ° C., and the difference is 42 ° C. At the moment when the main valve 12 of the thermostat 1 is opened, the low temperature cooling water flows from the lower part of the radiator 22, so that the water temperature of B further decreases by 13 ° C., and the difference from the water temperature in the thermostat housing 27 is 55 ° C. To expand. The area shown by the diagonal lines between A and B is the heat energy loss between them. Note that the diameter or time is zero when the water temperature of A is 60 ° C.

The thermal response of the thermostat 1 is considerably delayed from the thermal response of the cooling water. Therefore, the main valve 12 opens the valve after the water temperature becomes considerably higher than the specified valve opening temperature. Similarly,
Close the valve after the water temperature has dropped significantly below the specified valve closing temperature. A large thermal overshoot occurs in the initial stage of opening and closing of the main valve 12, and a surge pressure peak occurs upstream of the main valve when the main valve is closed.

The overshoot and the surge pressure may cause cracks in the cylinder block and cylinder head, and the thermostat 1 and the radiator 2
2. Shorten the life of the water pump 28 and the like.

Therefore, in the present invention, at least one small hole 19 is opened in the flange 16 of the thermostat by eliminating the conventional jiggle valve mechanism (FIG. 8). Even with this hole, the engine will start immediately with no warm-up time due to the cold start injectors injected into the throttle body under computer control.

By providing the small holes 19, the flange 16
The inner and outer water pressures become equal, and the return spring 13
, The valve opening speed of the main valve 12 can be increased. That is, if there is no hole, the water pressure in the cap 26 is considerably high in FIG. 6, and the spring constant of the spring 12 becomes high to keep the main valve closed, and the valve opening speed becomes low. The thermostat of the present invention preserves 50% of its capacity, so that all operations are performed quietly and quickly, so that engine vibration is reduced and engine life is increased.

Table 3 shows the results of the durability test of four thermostats of the present invention, and Table 4 shows the results of four conventional thermostats. The change value of the lift, which is the most important factor for the durability of the thermostat, is smaller than the conventional one by more than one order of magnitude, and the change from the initial stage is almost equal to zero.

The thermostat of the present invention described above has the same rod diameter, cylinder internal volume, and cylinder thickness as the conventional thermostat. Even so, such an unprecedented result was obtained, but by taking the following measures, the upper limit of the cooling water temperature, 81 ° C., can be further reduced.

That is, for example, in FIG. 2, another wax whose melting temperature is 3 ° C. faster than the line X is used, and
The temperature can be lowered to 78 ° C. In any case, lower the temperature of the cooling fan switch ON in steps of 1 ° C and check.

FIG. 9 shows that the cooling fan is electrically
FIG. 4 is an enlarged cross-sectional view of the contact fan switch 44 which performs N, OFF control, and its actual size is shown at the lower right. In FIG. 9, a small thermo-actuator 45 mounted on a fan switch is hermetically engaged with a rod 46 and a lower end surface of a guide member 47 slidably engaged with the rod, and is also slidable on the rod 46. A required amount of lubricating oil 49 is sealed in a space formed between the bottom inner surface of the elastic seal spool 48 and the lower end surface of the rod, and the four members are integrally filled with wax 50. It is configured to be inserted into the cylinder 51 and air-tightly pressed.

A thermo-actuator 45 is press-fitted and fixed to the lower end of the housing 52, and a stop ring 5 is inserted into the rod 46.
A push rod 55 for loading a return spring 54 onto the switch 3 protrudes through a center hole of the housing 52 and is slidable.
It faces the back of the movable contact 58 in the case 57.

The open free end of the thin phosphor bronze plate 60 for fixing the fixed contact 59 is fixed to the inside of the switch case 57 by the fastener 6.
It is raised at the front jaw, fixed to the lower end of the positive terminal 62, and integrally formed with an electric insulating mold 63. The fixed contact 59 is located in the switch case 57 and
8. A thin phosphor bronze disk 64 for fixing the movable contact 58 is curved so as to snap to the fixed contact 59, and the outer periphery thereof is a stop plate 65 and a spring 66.
Support with. These contact mechanisms are built in the switch case 57, and the upper peripheral surface of the case 57 is pressurized as shown in the figure to form a cooling fan switch.

When the temperature of the engine cooling water rises, the wax in the thermo-actuator 45 expands and increases in volume, and the rod 46 rises and the stop ring 5 fixed to the rod is raised.
3 push rod 55 is advanced against return spring 54. And for example, the water temperature is 81 ° C
, The push rod 55 moves forward and the movable contact 58
Is turned on and the switch is turned on. When the water temperature falls, the wax shrinks, and the push rod 55 retreats this time by the return spring 54, and the movable contact reversely turns off and the switch is turned off.

The optimum starting temperature of the cooling fan switch is determined by lowering the temperature in steps of 1 ° C. in advance, and the optimum part of the engine cooling system is selected and screwed in so that the heat-sensitive cylinder is mounted in the cooling water. is there. FIG. 10 shows a self-recording of the water temperature versus the elapsed time when the contact cooling fan switch is set to 75 ° C. Until the temperature reaches 75 ° C., the temperature of A ′ (FIG. 12) is 1 ° C. higher than the temperature B of B ′ (FIG. 12), but reaches 75.5 ° C. With the upper limit of 0.5 ° C., they are almost the same, and never exceed 75.5 ° C.

FIG. 11 is an enlarged sectional view of a contactless cooling fan switch 67 having a built-in semiconductor temperature sensor, and its actual size is shown at the lower right. A case 69 is provided on the upper part of
Is fixed, and an insulator 71 for integrally molding the + terminal 70 with an electric insulating mold is accommodated in the case 69.

A semiconductor temperature sensor 72 is provided inside the main body 68.
+ Terminal 73 is connected to terminal 70, and ground terminal 74 is connected to case 69, respectively. Then, the inside is hardened by, for example, an epoxy mold. 75 is the inlet. After the injection, the injection port is closed with a mold. The embodiment in which the ON of the non-contact type cooling fan switch is set to 75 ° C. is exactly the same as FIG.

FIG. 12 shows an example of an automobile engine cooling system according to the present invention. The same parts as those of the engine cooling system of FIG. 6 are denoted by the same reference numerals. The contactless cooling fan switch 67 is attached by deforming the thermostat cap 26. In the thermostat 1, the thickness of the elastic seal spool is made extremely thin, the spring constant of the return spring is halved, and a small hole is formed by removing the conventional jiggle valve mechanism from the flange surface (FIG. 8). 76 is a fan drive motor. In the figure, A 'is a measuring point of the water temperature in the thermostat housing 27, and B' is a measuring point of the water temperature in the thermostat cap 26.

[0045]

As is apparent from the above, according to the present invention, the thickness of the seal spool is thin, the pressures inside and outside the seal spool are equal, the frictional resistance of the seal spool against the rod becomes zero, and the main valve is closed. The valve can be opened rapidly at low wax pressure, ie at low cooling water temperature. In addition, since a small hole is formed in the flange through the valve seat where the main valve closes, the pressure inside and outside the flange becomes equal, thereby reducing the spring constant of the return spring, and in this regard, the operating speed of the main valve is further increased. It can be raised and opened at low temperatures. Thus, the saving fuel consumption, increase the life of the engine, _NO X,
It can reduce CO ₂ and contribute to prevention of global warming.

[Brief description of the drawings]

FIG. 1 shows an oil pressure-valve lift test apparatus for an elastic seal spool using hydraulic pressure instead of wax pressure.

[Fig. 2] Conventional new type wax type thermostat Y
5 is a diagram of a cooling water temperature versus a valve lift of the wax type thermostat X of the present invention.

FIG. 3 is a cross-sectional view of the wax type thermostat for an automobile engine according to the present invention, showing a main valve in a fully closed state.

FIG. 4 is a cross-sectional view of the wax type thermostat for an automobile engine according to the present invention when the main valve is fully opened.

FIG. 5 shows a jiggle valve mechanism.

FIG. 6 is a cooling system for an automobile engine constituted by a conventional thermostat with a jiggle valve mechanism.

FIG. 7 shows a self-recording of the flow rate, temperature, and elapsed time of the cooling water in FIG.

FIG. 8 is a sectional view showing small holes in the flange surface of the wax type thermostat for an automobile engine of the present invention.

FIG. 9 is a sectional view of a contact cooling fan switch.

FIG. 10 shows a self-recording of cooling water temperature versus elapsed time of a contact cooling fan switch.

FIG. 11 is a sectional view of a contactless cooling fan switch having a built-in semiconductor temperature sensor.

FIG. 12 is an automotive engine cooling system comprising a non-contact cooling fan switch also incorporating a semiconductor temperature sensor of the invention in conjunction with a wax type thermostat of the automotive engine of the invention having high cooling efficiency.

DESCRIPTION OF SYMBOLS 1 Thermostat 20 Water jacket 2 Thermoactuator 21 Outlet of water jacket 3 Rod 22 Radiator 4 Guide member 23 Inlet of radiator 5 Elastic seal spool 24 First channel 6 Lubricating oil 25 Radiator Outlet 7 Wax 26 Thermostat cap 8 Thermal cylinder 27 Thermostat housing 9 Valve seat 28 Water pump 10 Housing 29 Water jacket inlet 11 Frame 30 Second water passage 12 Main valve 31 Bypass water passage 13 Return spring 32 Bypass Water channel opening 14 Apex 33 Cooling fan 15 Bypass valve 44 Contact cooling fan 16 Flange surface switch 17 Jiggle valve mechanism 67 Using semiconductor temperature sensor 18 Jiggle valve Contactless cooling fan 19 Small hole switch 76 Fan drive motor

Claims (1)

(57) [Claims] A first water passage communicating the outlet of the water jacket of the engine with the radiator, a second water passage communicating the inlet of the radiator with the water jacket, and a bypass water passage communicating the first second water passage; A housing provided at the intersection of the second water passage and the bypass water passage, a rod fixed to the housing, a guide member slidably engaged with the rod, and a base surrounded by the guide member and surrounding the rod. An elastic seal spool that is hermetically engaged, lubricating oil sealed in the space between the rod and the seal spool, a heat-sensitive cylinder housing the guide member and the seal spool, and a heat-sensitive cylinder sealed in the heat-sensitive cylinder A wax, a main valve fixed to the guide member for opening and closing the second water passage, and a bypass valve for opening and closing the bypass water passage, and a valve seat, and fixed to the housing. A return spool for biasing the main valve toward the valve seat, wherein a water pressure is applied to the inner and outer surfaces of the flange when the main valve is closed. The thickness of the contacting portion is within the range of 25% to 5% of the rod diameter, at least one small hole is formed in the flange, and the operating temperature range of the main valve is within the range where the wax solid changes to a liquid. , The thickness of the seal spool and the spring constant of the return spring are selected, a cooling fan switch that operates the cooling fan of the engine is provided, and the upper limit of the temperature of the cooling water is solid wax. A cooling system for an automobile engine, wherein an operating temperature of a cooling fan switch is determined so as to fall within a range from a liquid to a liquid.