JPS6344931B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine cooling system, and particularly to a spark ignition engine, from the viewpoint of engine output performance, fuel efficiency, exhaust gas countermeasures, etc. The present invention relates to a cooling device configured to individually control the temperature of the cylinder block and the temperature of the cooling water flowing through the water jacket of the cylinder block.

It has long been known that in spark ignition engines, if the cylinder head is strongly cooled, the mechanical octane number will improve, the occurrence of knocking will be suppressed, and the output performance and fuel efficiency of the engine will be improved accordingly. It is being

However, in conventional water-cooled engines, the cooling water flowing through the water jacket provided in the cylinder head and the cooling water flowing through the water jacket provided in the cylinder block pass through a radiator in the middle. The temperature of the cooling water flowing through the cylinder head water jacket and the cylinder block water jacket cannot be individually controlled. For this reason, in a water-cooled engine such as the one described above, if you try to cool the cylinder head strongly by lowering the temperature of the cooling water flowing through the water jacket of the cylinder head, the temperature of the cooling water flowing through the water jacket of the cylinder block will decrease. The temperature also decreases, and the temperature of the engine lubricating oil, which is strongly affected by the temperature of the cooling water flowing through the cylinder block water jacket, also decreases, increasing friction loss in the engine, and the temperature of the peripheral wall of the combustion chamber decreases. This causes a problem in that the concentration of hydrocarbons in the exhaust gas increases.

In view of the above-mentioned problems, a first water jacket provided on the cylinder head, a second water jacket provided on the cylinder block, and a cooling water flow passing through the first and second water jackets. a radiator; a first reflux passage connecting the outlets of the first and second water jackets to their inlets and including the radiator in the middle; a second reflux passage that connects the outlets of the first and second water jackets to their inlets and does not include the radiator; and and a switching valve for switching the connection of the first and second recirculation passages to the second water jacket, and the switching valve has a switching valve that switches the temperature of the cooling water flowing through the second water jacket to a second water jacket. When the water temperature is lower than the first temperature, the second reflux passage is connected to the first and second water jackets, the first reflux passage is disconnected from the first and second water jackets, and the water temperature is lower than the first water jacket. When the temperature is higher than one temperature and lower than a second temperature higher than the first temperature, the first reflux passage is connected to the first water jacket, and the second reflux passage is connected to the second water jacket. A cooling device configured to connect the first reflux passage to the first and second water jackets when the water temperature is equal to or higher than the second temperature is disclosed by the same applicant as the present applicant. It has already been proposed.

In the cooling device as described above, when the temperature of the cooling water flowing through the second water jacket is higher than the first temperature, in other words, after warm-up is completed, the cooling water flowing through the first water jacket is cooled. Only water always returns to the first water jacket via the first return passage containing the radiator, and the cooling water that flows through the second water jacket only occurs when the water temperature of this water jacket exceeds the second temperature. The cylinder head is strongly cooled because the water is returned to the second water jacket via the first return passage, and at other times it is returned to the second water jacket via the second return passage that does not include a radiator. However, the cylinder block is not strongly cooled, and the cylinder block is kept at an appropriate temperature in the warmed-up state, making it possible to improve the engine's mechanical octane number without increasing engine friction loss or increasing the hydrocarbon concentration in the exhaust gas. , This makes it possible to improve the output performance and fuel efficiency of the engine. Furthermore, in this cooling device, during warm-up, the respective cooling waters that have flowed through the first and second water jackets are joined together through the second return passage and returned to the water jacket. Therefore, during warm-up, the cooling water that has flowed through the first water jacket and the cooling water that has flowed through the second water jacket do not merge with each other but flow back into each water jacket individually. The cylinder block warms up quickly, and the cylinder block warm-up time is comparable to the warm-up time of a conventional water-cooled engine as described above. After the cylinder block has been warmed up, the cooling water that has flowed through the first water jacket is cooled without being temperature controlled by the radiator, so the temperature of this cooling water drops to almost the outside temperature, and this Therefore, especially in the winter when the outside temperature is low, the temperature of the cooling water flowing back into the first water jacket may become very low.

By the way, from the perspective of the overall performance of the engine, it is not necessarily the case that the cylinder head can always be strongly cooled without limit; in winter when the outside air temperature is low, the cylinder bed may not be cooled even if it is not strongly cooled. Although the mechanical octane number of the engine improves as the intake air temperature decreases, if the cylinder head is cooled too much, the concentration of hydrocarbons in the exhaust gas may increase, and fuel efficiency may worsen. .

Furthermore, when engine cooling water is used as a heat source for the heater core for heating the inside of the car, in the above-described cooling system, the heater for heating the inside of the car uses the cooling water flowing through the second recirculation passage.
In this case, during warm-up, as mentioned above, the cooling water that has flowed through the first and second water jackets joins and circulates through the second recirculation passage, so the amount of heat received by the cylinder head and cylinder block depends on the amount of heat received by the cooling water. The amount of heat radiated by the heater for heating the car interior is covered, and a sufficient amount of heat is supplied to the heater, but after warm-up is completed, the heat of the cooling water that has flowed through the first water jacket is radiated by the radiator, and the second water jacket is heated. Since only the cooling water that has flowed through the second water jacket circulates through the second recirculation passage, the amount of heat radiated by the heater is covered only by the amount of heat received by the cylinder block. The amount of heat received by the cooling water of the cylinder block is generally less than half of the sum of the amount of heat received by the cylinder head and the cylinder block.
When the heater is operated at a low load, the cooling water flowing through the second water jacket alone does not supply enough heat to the heater. In such a state, the cooling water flowing through the second water jacket is deprived of heat by the heater and its temperature decreases to below the first temperature. Then, as during warm-up, the cooling water that has flowed through the first and second water jackets joins each other and begins to circulate through the second recirculation passage, but the cooling water that has flowed through the first water jacket Up until now, the cooling water has been cooled by a radiator and has reached almost the outside temperature.
When this mixes with the cooling water that has flowed through the second water jacket, the temperature of the mixed cooling water decreases, and the water temperature at the inlet of the heater further decreases. Since the amount of heat received by the cooling water of the cylinder head and cylinder block is larger than the amount of heat radiated by the heater, the temperature of the cooling water gradually rises and returns to normal. A problem occurs in which the power decreases.

The present invention not only controls the temperature of the cooling water flowing through the second water jacket after warm-up is completed, but also controls the temperature of the cooling water flowing through the first water jacket in accordance with the outside air temperature. However, it is possible to improve the engine's mechanical octane number without overcooling the cylinder head, thereby improving the engine's output performance and fuel efficiency without increasing the hydrocarbon concentration in the exhaust gas or causing insufficient heat dissipation from the heater. The aim is to provide an improved cooling system that can

According to the present invention, in the cooling device as described above, a bypass passage bypassing the radiator and connecting the middle of the first recirculation passage to the inlet of the first water jacket; a temperature sensor for detecting outside air temperature; and a temperature of the cooling water flowing through the first water jacket to a temperature set such that the lower the outside air temperature, the higher the temperature of the cooling water detected by the temperature sensor. This is achieved by an engine cooling system having a flow control valve for controlling the flow rate of cooling water passing through the bypass passage.

The invention will now be described in detail by way of example embodiments with reference to the accompanying drawings.

FIG. 1 is a diagram showing one embodiment of an engine cooling device according to the present invention. In Figure 1, 1
1 shows an engine, and this engine 1 mainly has a cylinder head 2 that defines the head of the combustion chamber of each cylinder, and a cylinder block 3 that defines the peripheral wall of the combustion chamber. The cylinder head 2 and cylinder block 3 each have a water jacket 4,
5 are provided separately from each other, so that cooling water flows through these water jackets individually.

Water pumps 10, 11 are connected to the inlets 6.7 of the water jackets 4, 5, and the water pumps supply cooling water into each water jacket. Entrance 6,7
The cooling water supplied to the water jackets 4 and 5
The cylinder head 2 and the cylinder block 3 are cooled in the meantime, and reach the cooling water outlets 8 and 9.

Outlet 8 via conduit 12 and outlet 9 via conduit 1
3 and is connected to one port of a control valve 14 via a conduit 16 having a control valve 15 in the middle. The control valve 14 is connected at its other port via a conduit 17 to an inlet 19 of a radiator 18 . The outlet 20 of the radiator 18 is connected to the water pump 10 via conduits 21, 22 and to the water pump 11 via conduits 21, 23, respectively.

Further, the outlet 8 is connected to the middle of the conduit 23 via the conduits 12 and 16 and the conduit 24, and the outlet 9 is connected to the middle of the conduit 23 via the conduits 13 and 24.

25 indicates a heater core for heating the inside of the car.
The heater core is connected to the upstream part of the conduit 24 at its inlet via a conduit 26 and to the downstream part of the conduit 24 at its outlet via a conduit 27. conduit 2
An on-off valve 28 is provided in the middle of the valve 6.

The conduit 17 is connected to the conduit 21 via a bypass conduit 29 in the middle thereof. Bypass conduit 29
The conduit is made of tubing with a smaller diameter than other conduits. A control valve 30 is provided in the middle of the conduit 17 downstream from the connection between the conduit 17 and the bypass conduit 29 .

Water temperature sensors 3 are installed in the middle of the conduits 12 and 13, respectively.
1 and 32 are provided, and this water temperature sensor is adapted to detect the temperature of the cooling water at the outlet of each water jacket. Temperature sensor 3
The temperature signals generated by 1 and 32 are sent to the control device 33, respectively.
is input to.

The control device 33 includes a well-known arithmetic control circuit including a comparison circuit, etc., and the water temperature sensor 3
In addition to the temperature signals generated by sensors 1 and 32, a temperature signal generated by a temperature sensor 49 is input. The temperature sensor 49 is provided in the carburetor 45 for supplying the air-fuel mixture to the engine 1, and is adapted to detect an intake air temperature that is substantially equal to the outside air temperature. The control device 33 outputs a valve closing signal to the control valve 14 and a valve opening signal to the control valve 15 when the water temperature of the cooling water detected by the water temperature sensor 32 is below the first temperature, so that the water temperature reaches the first temperature. When the water temperature is above the second temperature and below the second temperature higher than the first temperature, a valve open signal is output to the control valve 14, and a valve close signal is output to the control valve 15, and when the water temperature is above the second temperature, the water temperature is equal to or higher than the second temperature. A valve opening signal is output to each of the control valves 14 and 15. Further, the control device 33 controls the cooling water flowing through the water jacket 4 to increase in accordance with the intake air temperature detected by the temperature sensor 49, as shown in FIG. 2, for example, as the intake air temperature decreases. A set temperature is set, and when the water temperature sensor 32 detects a second temperature or lower and the temperature of the cooling water detected by the water temperature sensor 31 is below the set temperature, a valve opening signal is sent to the control valve 30.
A valve opening signal is output when the water temperature is equal to or higher than the set temperature.

Next, the operation of the cooling device constructed as described above will be explained.

First, a description will be given of when the water temperature detected by the temperature sensor 32 is below the first temperature, for example below 80°C, that is, during engine warm-up. At this time, the control valve 14 is closed and the control valve 15 is opened in response to a command signal generated by the control device 33.
Therefore, at this time, the cooling water that has flowed through the water jacket 4 of the cylinder head 2 and has reached its outlet 8 flows through the conduits 12, 16 and the control valve 15 to the conduit 24, and also flows through the water jacket 5 to its outlet 8. The cooling water that has come to the outlet 9 flows through the conduit 13 to the conduit 24, and these two types of cooling water join each other in the conduit 24 and reach the conduit 23, and a part of it is pumped into the water jacket from the inlet 7 by the water pump 11. It was returned to 5,
The rest is connected to the water pump 10 via conduits 21 and 22.
The water is returned to the water jacket 4 through the inlet 6. In this manner, while the engine is warming up, all of the cooling water flowing through the water jackets 4 and 5 does not flow to the radiator 18, but instead joins and circulates, so that the cylinder head 2 and the cylinder block 3 are warmed up at the same time and in the same way. You will be forced to do so. To explain the case where the heater is used in such a state, when the on-off valve 28 opens, a portion of the cooling water flowing through the conduit 24 flows through the conduit 26 to the heater core 25, and is cooled by a blower (not shown). Heat is exchanged with the blown air to radiate heat, and then the conduit 27
and then returns to conduit 24. Heater core 25 at this time
Since the amount of heat radiated is covered by the amount of heat received by the cooling water in the cylinder head 2 and cylinder block 3, a sufficient amount of heat is supplied to the heater core 25, and there is no shortage of heat radiated from the heater core 25.

Next, the water temperature sensor 32 detects a temperature equal to or higher than the first temperature, e.g.
The following describes what happens when a temperature of 80°C or higher is detected, that is, after the engine has warmed up. At this time, the control device 33
The control valve 14 is opened by the control signal generated by
Control valve 15 is open. At this time, the control device 33 outputs a valve opening signal to the control valve 30 if the temperature detected by the water temperature sensor 31 is higher than the set temperature set according to the intake air temperature, and if the detected temperature is lower than the set temperature, the control device 33 controls the control valve 30. A valve closing signal is output to the valve 30.

At this time, the cooling water that has flowed through the water jacket 4 of the cylinder head 2 is transferred from the outlet 8 to the conduit 1.
2, flow through control valve 14 and conduit 17 to control valve 30. If the control valve 30 is open at this time, most of this cooling water flows to the radiator 18, is cooled as it passes through the radiator, and is cooled through the conduits 21, 22.
The remaining cooling water is returned to the water jacket 4 from the inlet 6 by the water pump 10 through the bypass conduit 29 and the conduit 22, and the remaining cooling water is returned from the inlet 6 by the water pump 10 together with the cooling water that has passed through the radiator 18 as described above. jacket 4
will be returned to. As a result, the cooling water flowing through the water jacket 4 becomes lower in temperature due to the cooling effect of the radiator 18. The temperature of the cooling water is detected by a water temperature sensor 31, and the water temperature sensor detects that the temperature of the cooling water has fallen below a set temperature that is set according to the intake air temperature as shown in FIG. Then, the computer 33 outputs a valve closing signal to the control valve 30. This causes the control valve 30 to close. When the control valve 30 is closed, the entire amount of cooling water flowing through the conduit 17 is returned to the water jacket 4 from the inlet 6 by the water pump 10 without passing through the bypass conduit 29 and the conduit 22 and the radiator 18. When the temperature of the cooling water flowing through the water jacket 4 falls below the set temperature, the cooling water flows through the radiator 1.
Since the cooling water circulates without flowing through the cooling water 8, the temperature of this cooling water rises again. When the water temperature rises above the set temperature, the control valve 30 is activated again by the control device 33.
A control signal causes the valve to open, allowing the cooling water flowing through the conduit 17 to pass through the radiator 18.
Thereafter, by repeatedly opening and opening the control valve 30, the temperature of the cooling water flowing through the water jacket 4 is maintained approximately at the set temperature. Since the set temperature increases as the intake air temperature decreases, the temperature of the cooling water flowing through the water jacket 4 becomes relatively high in the winter when the intake air temperature is low, and becomes relatively low in the summer when the intake air temperature is high. It is maintained.

This prevents the cylinder head from being overcooled in the winter, and avoids deterioration in engine performance due to overcooling of the cylinder head. When the intake air temperature is low, the temperature of the cooling water flowing through the water jacket of the cylinder head is kept at a relatively high temperature, but this temperature is lower than the temperature at which the cooling water on the cylinder block side completes warming up, and Sometimes, due to the low intake air temperature, the engine's mechanical octane number hardly decreases and remains almost constant regardless of changes in the intake air temperature.

On the other hand, the cooling water flowing through the water jacket 4 of the cylinder block 3 flows from the outlet 9 to the conduit 1.
3, 24, and 23, and is returned to the water jacket 5 from the inlet 7 by the water pump 11. In this way, the cooling water flowing through the water jacket 5 circulates through the same route as during warm-up, so the temperature of the water further increases gradually. When the temperature of the cooling water reaches a second temperature or higher, for example, 95° C. or higher, and this is detected by the water temperature sensor 32, the controller 33
The control valves 15 and 30 are opened by this signal. At this time, part of the cooling water that has flowed through the water jacket 5 flows through the conduit 13, the control valve 15, the conduit 16,
It flows through the control valve 14, the conduit 17, and the control valve 30 to the radiator 18, where it is cooled as it passes through the radiator 18, and then passes through the conduits 21 and 23 and is pumped from the inlet 7 to the water jacket 5 by the water pump 11.
will be returned to. Also, at this time, the remaining cooling water is
3, 24, 23 and the radiator 18 as described above.
It is returned to the water jacket 5 from the inlet 7 by the water pump 11 along with the cooling water that has passed through the water jacket.
As the cooling water that has passed through the radiator 18 flows through the water jacket 5, the temperature of the cooling water decreases. When the temperature of the cooling water falls below the second temperature again, the control valve 15 closes and the water jacket 5 is connected to the radiator 18.
The cooling water that has passed through will no longer be supplied. Thereafter, the temperature of the cooling water flowing through the water jacket 5 is maintained at the second temperature (approximately 95° C.) by repeatedly closing and opening the control valve 15.

Next, a case will be described in which the heater is used after the above-mentioned warm-up is completed. When the heater is used, the on-off valve 28 is opened and a portion of the cooling water flowing through the conduit 24 flows through the heater core 25, as in the above-mentioned warm-up. However, at this time, the amount of heat dissipated by the heater core 25 is covered only by the amount of heat received by the cooling water flowing through the water jacket 5, so especially when the engine is operated at low rotation and low load, the heat dissipated from the heater core 25 is The amount of heat received by this cooling water is insufficient compared to the capacity, resulting in a decrease in the temperature of the cooling water flowing through the water jacket 5. When the temperature of the cooling water flowing through the water jacket 5 decreases to below the first temperature and this is detected by the water temperature sensor 32, the control device 33 causes the control valve 14 to close. A valve signal and a valve opening signal are output to the control valve 15, whereby the control valve 14 is closed and the control valve 15 is opened. That is, at this time, the cooling water starts to flow in the same way as during warm-up, and the heater core 25
The amount of heat radiated is covered by the amount of heat received by the cooling water of the cylinder head 2 and cylinder block 3, respectively. After warming up, remove the water jacket 4.
Since the temperature of the cooling water flowing through the conduit 24 is maintained at the set temperature, the temperature of the cooling water flowing through the conduit 24 further decreases when the switching valves 14 and 15 switch to create a water flow system similar to that during warm-up. Sometimes. The temperature of this cooling water gradually rises and returns to normal because the amount of heat received by each of the cylinder head 2 and cylinder block 3 is greater than the amount of heat radiated by the heater core 25.

If the control valve 30 and the conduit 29 are not provided, when the outside air temperature is low after warm-up is completed, the temperature of the cooling water flowing through the water jacket 4 will drop to a temperature close to that temperature, and therefore the above-mentioned problem will occur. Although it takes a long time for the temperature of the cooling water flowing through the conduit 24 to recover when the control valve is switched, according to the cooling device of the present invention, when the outside air temperature (intake air temperature) is low, the heater is not used. Since the temperature of the cooling water flowing through the water jacket 4 is maintained at a relatively high temperature as described above,
The time required for the temperature of the cooling water to return is shortened, and the period during which the amount of heat dissipated from the heater core 25 is insufficient can be shortened.

Also, as the temperature of the cooling water on the cylinder head side is lower than that on the cylinder block side, heat flows from the cylinder block to the cylinder head due to heat conduction and other factors, reducing the amount of heat received by the cooling water on the cylinder block side. Since the ability of the cooling water on the cylinder block to supply heat to the heater core is reduced, the number of times that the temperature of the cooling water on the cylinder block side drops below the warm-up temperature increases due to the use of the heater, as described above.

In this regard, in the present invention, when the outside air temperature becomes low, the cooling water temperature of the cylinder head increases, so the reduction in the amount of heat received by the cooling water on the cylinder block side is suppressed, and as the heater is used, the cooling water on the cylinder block side increases. The number of times the temperature drops to the temperature before completion of warm-up is reduced.

As described above, according to the present invention, it is possible to solve the problem of insufficient heat dissipation of the heater when the heater is needed, such as in the winter, and to make full use of the radiator's capacity during the summer, when the heater is not required and the cooling capacity of the radiator is reduced. It will be appreciated that cooling of the cylinder head can be effected effectively.

Although the present invention has been described above with reference to specific embodiments, it is clear to those skilled in the art that the present invention is not limited thereto and that various embodiments can be made within the scope of the present invention. Will.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of an engine equipped with a cooling device according to the present invention, and FIG. 2 is a graph showing the relationship between the intake air temperature and the set temperature of the cooling water flowing through the water jacket of the cylinder head. . 1...Engine, 2...Cylinder head, 3...
...Cylinder block, 4,5...Water jacket, 6,7...Inlet, 8,9...Outlet, 10,
11... Water pump, 12, 13... Conduit,
14, 15... Control valve, 16, 17... Conduit, 1
8...Radiator, 19...Inlet, 21-24...
... Conduit, 25 ... Heater core, 26, 27 ... Conduit, 28 ... On-off valve, 29 ... Bypass conduit, 3
0... Control valve, 31, 32... Temperature sensor, 33
...control device, 45 ... vaporizer, 49 ... temperature sensor.

Claims (1)

[Claims] 1 a first water jacket provided on the cylinder head, a second water jacket provided on the cylinder block, and a first water jacket for urging cooling water flow through the first and second water jackets, respectively. and a second water pump, a radiator, a first reflux passage connecting the outlets of the first and second water jackets to their inlets and including the radiator in the middle; a second return passage that connects the outlet of the water jacket to the inlet thereof and does not include the radiator in the middle; a connection of the first and second return passages to the first water jacket; a switching valve that switches connection of the first and second return passages to the water jacket, and the switching valve is configured to operate when the temperature of the cooling water flowing through the second water jacket is lower than or equal to a first temperature. The second reflux passage is connected to the first and second water jackets, the first reflux passage is disconnected from the first and second water jackets, and the water temperature is equal to or higher than the first temperature. When the water temperature is lower than or equal to a second temperature higher than the first temperature, the first reflux passage is connected to the first water jacket, the second reflux passage is connected to the second water jacket, and the water temperature is lowered. When the temperature is higher than the second temperature, the first reflux passage is connected to the first and second water jackets, and the first reflux passage is connected to the first reflux passage midway through the first reflux passage, bypassing the radiator. a bypass passage connected to the inlet of the first water jacket; a temperature sensor for detecting outside air temperature; An engine cooling device comprising: a flow control valve that controls a flow rate of cooling water passing through the bypass passage to control the temperature to a temperature set such that the lower the outside air temperature is, the higher the temperature is.