JP4151881B2 - Engine cooling system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine cooling apparatus in which cooling water is supplied from a radiator to a cylinder head and supplied from a cooling water passage in the cylinder head to a cooling water passage in a cylinder block.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, for example, a cooling device used for an automobile engine is configured as shown in FIG.
FIG. 4 is a diagram showing the configuration of a conventional engine cooling device. In the figure, reference numeral 1 denotes an engine, 2 denotes a cylinder block of the engine 1, 3 denotes a cylinder head, 4 denotes a cooling device, 5, 6, Reference numeral 7 denotes a radiator, a cooling water pump, and a thermostat constituting the cooling device 4.
[0003]
Cooling water passages 8 and 9 are formed in the cylinder block 2 and the cylinder head 3 , respectively. These cooling water passages 8 and 9 communicate with each other within the engine 1.
The cooling device 4 supplies cooling water to the cooling water passage 8 in the cylinder block 2 by the cooling water pump 6, cools the cooling water led out from the cylinder head 3 by the radiator 5, and then cools the cooling water in the cylinder block 2. It is configured to return to the passage 8. The cooling water inlet 5 a and the cooling water outlet 5 b of the radiator 5 are connected by a bypass passage 10 via a thermostat 7. In this cooling device 4, when the temperature of the cooling water is lower than the set temperature of the thermostat 7, the cooling water is caused to flow through the bypass passage 10, and when the temperature of the cooling water is higher than the set temperature, the cooling water is supplied to the radiator 5. Will be washed away.
[0004]
The cooling water that has passed through the radiator 5 or the bypass passage 10 in this way is supplied to the cooling water passage 8 in the cylinder block 2 by the cooling water pump 6. The cooling water enters the cooling water passage 9 in the cylinder head 3 in the engine 1, exits from the cooling water outlet 3 a of the cylinder head 3, and enters the thermostat 7.
[0005]
[Problems to be solved by the invention]
However, in the conventional cooling device 4 configured as described above, the cylinder head 3 is cooled by the cooling water after the cylinder block 2 is cooled. Therefore, the cylinder head 3 cannot be cooled efficiently. There was a problem. Since the cylinder head 3 constitutes the ceiling wall of the combustion chamber, it is desirable that the cylinder head 3 be cooled by cooling water having a lowest possible temperature.
[0006]
Such a problem can be solved to some extent by adopting a configuration in which the cooling water is first supplied to the cooling water passage in the cylinder head as disclosed in, for example, Japanese Patent Application Laid-Open No. 58-162716. it can. The cooling device disclosed in this publication is provided with a circulation passage in which the cooling water returns from the cooling water passage of the cylinder head to the cooling water passage through the radiator and the cooling water pump on the downstream side of the radiator. The cooling water is supplied from the cooling water passage to the cooling water passage of the cylinder block in the engine.
[0007]
The cooling water passage in the cylinder head is connected to the cooling water outlet of the cooling water pump via a cooling water inlet formed in one side of the cylinder head, and the cooling formed in the other side of the cylinder head. It is connected to a cooling water discharge passage through a water outlet, and is connected to a cooling water passage in the cylinder block through a communication passage formed for each cylinder.
The cooling water discharge passage is provided with a first thermostat of a radiator bypass passage at a downstream end portion, and is connected to a cooling water inlet of the radiator and the radiator bypass passage through the first thermostat. .
[0008]
The cooling water passage in the cylinder block is connected to the cooling water discharge passage through a cooling water outlet on one side of the cylinder block. A second thermostat is provided at the cooling water outlet of the cylinder block. When the temperature of the cooling water becomes higher than the set temperature and the second thermostat opens, the cooling water flows out to the cooling water discharge passage.
By supplying the cooling water directly to the cylinder head in this way, the cooling water having the lowest temperature is supplied to the cylinder head, and the cylinder head can be efficiently cooled.
[0009]
However, while this cooling device can cool the cylinder head efficiently, there is a problem that the cylinder block is hardly cooled. This is because a part of the cooling water in the cylinder head is supplied to the cooling water passage in the cylinder block, passes through this cooling water passage and exits from the cooling water outlet of the cylinder block, and then from the cooling water outlet of the cylinder head. It is thought that the cause is that it merges with the other cooling water that has come out in the cooling water discharge passage. That is, the resistance when the cooling water passes through the cooling water passage in the cylinder block becomes larger than when the cooling water passes only through the cylinder head, and it becomes difficult for the cooling water to flow into the cooling water passage in the cylinder block from the cylinder head side. is there.
[0010]
The present invention has been made to solve such problems, and provides an engine cooling device that can efficiently cool the cylinder head and increase the amount of cooling water supplied to the cylinder block. The purpose is to do.
[0011]
[Means for Solving the Problems]
In order to achieve this object, an engine cooling apparatus according to the present invention has a circulation passage in which cooling water returns from the cooling water passage of the cylinder head to the cooling water passage through a radiator and a cooling water pump downstream of the radiator. In the cooling device for an engine in which the cooling water is supplied from the cooling water passage of the cylinder head to the cooling water passage of the cylinder block, the cooling water passage of the cylinder block is an independent cooling water passage through an on-off valve. A radiator bypass path is provided to connect to the cooling water passage between the radiator and the cooling water pump, and to connect the cooling water inlet of the radiator and the cooling water inlet of the cooling water pump, and the cooling water outlet of the radiator and the cooling water pump The radiator bypass passage thermostat is provided between the cooling water inlet of the radiator and the thermostat. The cooling water outlet of the radiator is selectively connected to the cooling water pump, and the portion of the thermostat housing that communicates with the cooling water inlet of the cooling water pump on the downstream side of the valve body is connected to the cooling water system of the cylinder block. The provided on-off valve is connected .
[0012]
According to the present invention, when the on-off valve provided in the cooling water system of the cylinder block is closed, the entire amount of cooling water passes through the cooling water passage in the cylinder head and flows through the circulation passage. When the on-off valve is open, a part of the cooling water in the cylinder head enters the cooling water passage in the cylinder block and sucks into the cooling water inlet side of the cooling water pump through the passage independent of the on-off valve. Is done. That is, in a state where the on-off valve is opened, a part of the cooling water supplied into the cylinder head is sucked into the cooling water pump through the cooling water passage and the on-off valve of the cylinder block, and the remaining portion passes through the circulation passage. It begins to flow.
[0013]
Therefore, since the cooling water that has passed through the on-off valve from the cooling water passage in the cylinder block is sucked into the cooling water pump without passing through the radiator, the cooling water passes through the cooling water system having the cooling water passage in the cylinder block. The resistance can be reduced.
[0015]
Further , according to the present invention , the temperature of the cooling water passing through the cooling water system of the cylinder block affects the opening and closing of the thermostat. For this reason, for example, even if the temperature of the cooling water is lower than the set temperature of the thermostat and the cooling water flows through the bypass passage, if the temperature of the cooling water in the cylinder block is higher than the set temperature, When the relatively high temperature cooling water enters the thermostat from the cooling water system of the cylinder block, the temperature of the thermostat rises, and the thermostat is switched between open and closed so that the cooling water passes through the radiator.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of an engine cooling apparatus according to the present invention will be described in detail with reference to FIGS.
1 and 2 are diagrams showing the configuration of the engine cooling device according to the present invention. FIG. 1 shows a state in which the first and second thermostats are closed, and FIG. 2 shows the first and second thermostats. Indicates open state. FIG. 3 is an enlarged cross-sectional view of the first thermostat.
[0017]
In these drawings, reference numeral 21 denotes an engine according to this embodiment. This engine 21 is a water-cooled four-cycle engine for automobiles, and cooling water is supplied to a cooling water passage 24 inside the cylinder head 23 and a cooling water passage 26 inside the cylinder block 25 by the cooling device 22 according to the present invention. Is done.
A cooling water passage 24 in the cylinder head 23 is connected to a circulation passage 27 described later, and is connected to a cooling water passage 26 in the cylinder block 25 by a communication passage 28 in the engine 21 .
[0018]
The circulation passage 27 includes a radiator 33 in which a cooling water inlet 32 is connected to a cooling water outlet 23 a of the cylinder head 23 via a first cooling water pipe 31, and a second cooling water pipe to the cooling water outlet 34 of the radiator 33. A first thermostat 36 having one end connected via 35, and a third bypass passage forming interposition between the other end of the first thermostat 36 and the first cooling water pipe 31. A cooling water pipe 37, a cooling water pump 40 having a cooling water inlet 39 connected to the first thermostat 36 via a fourth cooling water pipe 38, a cooling water outlet 41 of the cooling water pump 40, and the cylinder head 23. The fifth cooling water pipe 42 is connected to the cooling water inlet 23b. Since the radiator 33 and the cooling water pump 40 are the same as those used in the conventional cooling device, detailed description thereof will be omitted. The first thermostat 36 constitutes a thermostat according to the invention described in claim 2.
[0019]
As shown in FIG. 3, the first thermostat 36 is provided with a thermostat main body 44 inside a housing 43. As is well known, wax (not shown) built in the thermostat main body 44 is used. It has a structure that opens when it expands due to an increase in temperature. When the first thermostat 36 is opened, the cooling water is sucked into the cooling water pump 40 from the radiator 33 through the first thermostat 36, and the first thermostat 36 is closed, so that the cooling water is third cooled. The water pipe 37 (bypass passage) passes through the first thermostat 36 and is sucked into the cooling water pump 40. That is, the first thermostat 36 is configured to selectively connect the third cooling water pipe 37 (bypass passage) and the cooling water outlet 34 of the radiator 33 to the cooling water pump 49.
[0020]
The housing 43 of the first thermostat 36 is provided with a connection pipe 45 for connecting the second cooling water pipe 35 to one end portion in the axial direction (left-right direction in FIG. 3). A connecting pipe 46 for connecting the third cooling water pipe 37 is provided at the other end portion of the. In addition, a connecting pipe 47 for connecting the fourth cooling water pipe 38 is integrally formed in the central portion of the housing 43 in the axial direction, and a sixth pipe extending from the cylinder block 25 as will be described later. A connecting pipe 49 for connecting the cooling water pipe 48 (see FIGS. 1 and 2) is provided.
[0021]
The thermostat main body 44 provided in the housing 43 moves in the axial direction as the cylinder 52 supported by the housing 43 via the frame 51 and the volume of wax provided in the cylinder 52 change. The first valve body 53 and the second valve body 54, and the compression coil spring 55 that urges the valve bodies 53 and 54 in the closing direction (rightward in FIG. 3). In this thermostat main body 44, the volume of the wax increases as the temperature rises, so that the first valve body 53 and the second valve body 54 have the elastic force of the compression coil spring 55 from the fully closed position shown in FIG. 3 moves to the left in FIG.
[0022]
The first valve body 53 is formed at the center of the housing 43 connected to the connection pipe 45 provided at one end of the housing 43 and connected to the connection pipe 47. The communication port 58 communicating with the second water chamber 57 is opened and closed. The second valve body 54 opens and closes a communication port 60 that communicates the third water chamber 59 communicating with the connection pipe 46 provided at the other end of the housing 43 and the second water chamber 57. It is formed as follows.
[0023]
That is, when the temperature of the wax is low, the first thermostat 36 closes the cooling water passage leading to the cooling water outlet 34 of the radiator 33 by closing the first valve body 53 and the second valve body. 54 is opened, and passes through the cooling water passage including the third cooling water pipe 37 (bypass passage), the third water chamber 59, the second water chamber 57, the connecting pipe 47, the fourth cooling water pipe 38, and the like. Then, the cooling water pump 40 sucks the cooling water.
[0024]
On the other hand, when the temperature of the cooling water rises and the wax expands, the second valve body 54 is closed to close the cooling water passage leading to the third cooling water pipe 37, and the first valve body 53. Is opened, and a cooling water passage comprising the second cooling water pipe 35, the connecting pipe 45, the first water chamber 56, the second water chamber 57, the connecting pipe 47, the fourth cooling water pipe 38, etc. The cooling water is sucked into the cooling water pump 40 through it. The temperature of the cooling water when the first thermostat 36 is opened is generally set to 85 ° C. in this embodiment.
[0025]
As shown in FIGS. 1 and 2, the cooling water passage 26 in the cylinder block 25 has a cooling water outlet 61 formed on one side portion of the cylinder block 25, and the second cooling water outlet 61 is interposed in the cooling water outlet 61. The thermostat 62 and a sixth cooling water pipe 48 extending from the cooling water outlet 61 are connected to the first thermostat 36. Similar to the first thermostat 36, the second thermostat 62 has a structure that opens and closes by changing the volume of the wax. When the temperature of the cooling water is lower than the set temperature, the cooling water outlet 61 is closed and the cooling water temperature is reduced. Is configured to open the cooling water outlet 61 when the temperature becomes higher than the set temperature. The temperature at which the second thermostat 62 opens is set to approximately 105 ° C. in this embodiment. The second thermostat 62 constitutes an on-off valve according to the first aspect of the invention.
[0026]
As shown in FIG. 3, the downstream end of the sixth cooling water pipe 48 is connected to the connection pipe 49 of the first thermostat 36, and the first and second housings 43 of the first thermostat 36 The second water body 57 is connected to the cooling water inlet 39 of the cooling water pump 40 on the downstream side of the second valve bodies 53 and 54. The sixth cooling water pipe 48 is provided with an orifice 63 in the middle, and is preset so that the flow rate of the cooling water when the second thermostat 62 is opened becomes a predetermined flow rate. In this cooling device 22, the ratio between the flow rate of the cooling water passing through the cooling water passage 24 in the cylinder head 23 and the flow rate of the cooling water passing through the cooling water passage 26 in the cylinder block 25 is optimized. The opening degree of the orifice 63 is set.
[0027]
In the cooling device 22 configured in this way, when the temperature of the cooling water is relatively low, such as during warm-up operation, the first and second thermostats 36 and 62 are closed as shown in FIG. Become. In this state, the entire amount of cooling water circulates through the circulation passage 27 connected to the cooling water passage 24 in the cylinder head 23 as indicated by an arrow in FIG. That is, at this time, the cooling water enters the first thermostat 36 from the cooling water outlet 23 a of the cylinder head 23 through the first cooling water pipe 31 and the third cooling water pipe 37, and from the first thermostat 36. The water is sucked into the cooling water pump 40 through the fourth cooling water pipe 38. Then, the coolant is supplied from the coolant pump 40 through the fifth coolant pipe 42 to the coolant inlet 23 b of the cylinder head 23, and enters the coolant passage 24 in the cylinder head 23 from here.
[0028]
As the cooling water circulates in this way, the cooling water does not pass through the cooling water passage 26 in the cylinder block 25, so that the temperature of the cylinder block 25 easily rises. For this reason, this cooling device 22 can shorten the time required for the warm-up operation.
[0029]
By continuing the operation state, the temperature of the cooling water rises from the above-described state, and the first thermostat 36 is opened as shown in FIG. By opening the first thermostat 36, the downstream end of the third cooling water pipe 37 is closed, and the cooling water passes through the radiator 33 and the second cooling water pipe 35 from the first cooling water pipe 31 to the first cooling water pipe 37. 1 thermostat 36 is entered. For this reason, the cooling water cooled by the radiator 33 and having a relatively low temperature is supplied from the cooling water pump 40 through the fifth cooling water pipe 42 to the cooling water passage 24 in the cylinder head 23, and the cylinder head 23 is To be cooled.
[0030]
On the other hand, since the cooling water passage 26 in the cylinder block 25 does not enter the cooling water from the cylinder head 23 side when the second thermostat 62 is closed, the temperature of the cooling water in the cooling water passage 26 is The cylinder block 25 rises so as to follow the temperature rise. When the temperature of the cooling water in the cylinder block 25 rises and the second thermostat 62 opens, the cooling water in the cooling water passage 26 enters the first thermostat 36 through the sixth cooling water pipe 48. At the same time, cooling water is newly supplied from the cooling water passage 24 in the cylinder head 23 to the cooling water passage 26 in the cylinder block 25.
That is, the cooling water that has passed through the cooling water passage 26 in the cylinder block 25 enters the first thermostat 36 through a different path from the cooling water exited from the cooling water outlet 23a of the cylinder head 23, and the circulation. It is mixed with the cooling water flowing through the passage 27, sucked into the cooling water pump 40, and supplied to the cooling water passage 24 in the cylinder head 23.
[0031]
Since the second thermostat 62 opens and closes based on the temperature of the cooling water in the cylinder block 25, the first thermostat 36 is closed during the warm-up operation (the state in which the cooling water flows through the third cooling water pipe 37). ) May open. When the second thermostat 62 is opened while the first thermostat 36 is closed, cooling water having a relatively high temperature in the cylinder block 25 enters the first thermostat 36, and the first thermostat 36 has a temperature. Open by rising. As a result, although the temperature of the cooling water in the circulation passage 27 is relatively low, the first thermostat 36 is opened and the cooling water is cooled through the radiator 33.
[0032]
Therefore, according to the engine cooling device 22 according to this embodiment, when the second thermostat 62 is opened, a part of the cooling water supplied into the cylinder head 23 is part of the cooling water passage 26 of the cylinder block 25. To the cooling water pump 40 through the second thermostat 62, the sixth cooling water pipe 48, the first thermostat 36 and the fourth cooling water pipe 38, and the remainder from the cooling water outlet 23a of the cylinder head 23. It flows out to the first cooling water pipe 31.
[0033]
For this reason, the cooling water that has flowed out of the cooling water passage 26 in the cylinder block 25 through the second thermostat 62 is sucked into the cooling water pump 40 without passing through the radiator 33. The flow path resistance when the cooling water passes through the cooling water system having the passage 26 can be reduced. As a result, the flow rate of the cooling water flowing through the cylinder block 25 is increased, and the cooling efficiency of the cylinder block 25 can be improved.
[0034]
As shown in this embodiment, by setting the first thermostat 36 to open at about 85 ° C. and the second thermostat 62 to open at about 105 ° C., the coolant temperature during medium load operation can be changed to the cylinder. The optimum temperature around 110 ° C. is maintained at the cooling water outlet 23 a of the head 23. For this reason, by using this cooling device 22, combustion was improved in a practical operation range, fuel consumption was improved, and HC emissions were reduced.
[0035]
Further, since the sixth cooling water pipe 48 extending from the cylinder block 25 is connected to the first thermostat 36, the temperature of the cooling water passing through the cooling water system of the cylinder block 25 affects the opening and closing of the first thermostat 36. It becomes like this. For this reason, even if the cooling water flows through the third cooling water pipe 37 (bypass passage), the temperature of the cooling water in the cylinder block 25 rises and the second thermostat 62 opens, so that the relative The first thermostat 36 is opened and closed so that the cooling water having a high temperature enters the first thermostat 36 from the sixth cooling water pipe 48 and the temperature of the first thermostat 36 rises, and the cooling water passes through the radiator 33. Is switched. That is, the first thermostat 36 is opened with high accuracy so as to match the state of the engine.
[0036]
In the above-described embodiment, an example in which the first thermostat 36 and the second thermostat 62 are configured by wax thermostats has been described. However, these thermostats may be electrically operated. In particular, the second thermostat 62 has the same effect even if formed by any valve as long as it opens and closes the passage in response to a temperature change. Further, the second thermostat 62 may have a structure in which the temperature of the wall surface of the cylinder block 25 is detected by a sensor in addition to the coolant temperature.
[0037]
【The invention's effect】
As described above, according to the present invention, the cooling water that has passed through the on-off valve from the cooling water passage in the cylinder block is sucked into the cooling water pump without passing through the radiator. It is possible to reduce the flow path resistance when the cooling water passes through the cooling water system having. For this reason, the cooling water easily flows through the cooling water passage in the cylinder block while adopting a configuration in which the cooling water having a relatively low temperature flows into the cooling water passage in the cylinder head.
[0038]
Therefore, the cylinder head can be efficiently cooled, and the flow rate of the cooling water flowing through the cylinder block can be increased. Therefore, an engine cooling device capable of reliably cooling the cylinder head and the cylinder block is provided. can do.
[0039]
According to the second aspect of the present invention, the temperature of the cooling water passing through the cooling water system of the cylinder block affects the opening and closing of the thermostat. For this reason, for example, even if the temperature of the cooling water is lower than the set temperature of the thermostat and the cooling water flows through the bypass passage, if the temperature of the cooling water in the cylinder block is higher than the set temperature, When the relatively high temperature cooling water enters the thermostat from the cooling water system of the cylinder block, the temperature of the thermostat rises, and the thermostat is switched between open and closed so that the cooling water passes through the radiator.
Therefore, since the thermostat can be opened with high accuracy, a highly reliable engine cooling device can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an engine cooling device according to the present invention.
FIG. 2 is a diagram showing a configuration of an engine cooling device according to the present invention.
FIG. 3 is an enlarged cross-sectional view of a thermostat.
FIG. 4 is a diagram showing a configuration of a conventional engine cooling device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 21 ... Engine, 22 ... Cooling device, 23 ... Cylinder head, 24, 26 ... Cooling water passage, 25 ... Cylinder block, 27 ... Circulation passage, 31 ... First cooling water pipe, 33 ... Radiator, 35 ... Second cooling Water pipe 36 ... first thermostat 37 ... third cooling water pipe 38 ... fourth cooling water pipe 40 ... cooling water pump 42 ... fifth cooling water pipe 43 ... housing 44 ... thermostat main body 48 ... Sixth cooling water pipe, 53 ... first valve element, 54 ... second valve element, 56 ... first water chamber, 57 ... second water chamber, 59 ... third water chamber, 62 ... second Thermostat.

Claims (1)

The cooling water has a circulation passage that returns from the cooling water passage of the cylinder head to the cooling water passage through the radiator and the cooling water pump downstream of the radiator, and from the cooling water passage of the cylinder head to the cooling water passage of the cylinder block. In the cooling system for an engine to which cooling water is supplied, the cooling water passage of the cylinder block is connected to a cooling water passage between the radiator and the cooling water pump through an on-off valve and an independent cooling water passage ,
A radiator bypass passage is provided for connecting the cooling water inlet of the radiator and the cooling water inlet of the cooling water pump, and the thermostat of the radiator bypass passage is provided between the cooling water outlet of the radiator and the cooling water inlet of the cooling water pump. The thermostat is configured to selectively connect the bypass passage and the cooling water outlet of the radiator to a cooling water pump, and is connected to the cooling water inlet of the cooling water pump on the downstream side of the valve body in the housing of the thermostat. An engine cooling device comprising an open / close valve provided in a cooling water system of a cylinder block connected to a communicating portion .

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