JP5724596B2 - Engine cooling system - Google Patents

Description

  The present invention relates to an engine cooling apparatus.

  In an engine (internal combustion engine) mounted on a vehicle or the like, a water jacket is formed as a cooling water passage in each of the cylinder head and the cylinder block, and the cooling water is circulated through the water jacket by a water pump. I'm trying to cool it down. 2. Description of the Related Art As an engine cooling device, one that is configured to be able to supply cooling water discharged by a water pump to each of a water jacket of a cylinder head and a water jacket of a cylinder block is known. In this type of cooling device, the cooling state on the cylinder head side of the engine and the cooling state on the cylinder block side can be independently controlled.

  In the engine cooling apparatus as described above, when the temperature of the cooling water is relatively low, the cooling water supply to the cylinder jacket water jacket is stopped (or the flow rate is limited), and the water jacket of the cylinder head is stopped. Only cooling water is supplied. As a result, while suppressing an excessive increase in the temperature of the cylinder head, the temperature of the cylinder block is quickly increased to reduce friction loss in various parts of the engine within a short period of time after the engine is started. It is trying to improve.

  By the way, if all the cooling water from the water pump is supplied to the water jacket of the cylinder head while the supply of the cooling water to the water jacket of the cylinder block is stopped, the water jacket of the cylinder head is cooled more than necessary. Water may be supplied. Then, due to this, there is a concern that the cylinder head is excessively cooled, and the fuel consumption is deteriorated.

  Conventionally, while the engine is warming up, the supply of cooling water to the water jacket of the cylinder block is stopped by the block-side shut-off valve, and the opening area of the flow control valve is reduced to be supplied to the water jacket of the cylinder head. It has been proposed to limit the flow rate of cooling water (see, for example, Patent Document 1). However, the cooling device described in Patent Document 1 has a problem that the cost increases because both the above-described block-side shut-off valve and flow control valve use electronic control valves.

JP 2010-163920 A

  The present invention has been made in view of such problems, and suppresses overcooling of the cylinder head when the supply of cooling water to the water jacket of the cylinder block is stopped or the flow rate is restricted while reducing the cost. It is an object of the present invention to provide a cooling device for an engine that can be used.

  In the present invention, means for solving the above-described problems are configured as follows. That is, the present invention is an engine cooling apparatus configured to be able to supply cooling water discharged by a water pump to each of a water jacket of a cylinder head and a water jacket of a cylinder block, and A thermostat having a first valve for controlling the flow rate of the coolant supplied and a second valve for controlling the flow rate of the coolant supplied to the water jacket of the cylinder block is provided. The first valve includes the second valve. In the closed state, a flow rate limiting unit is provided that limits the flow rate of the cooling water supplied to the water jacket of the cylinder head.

  According to the engine cooling apparatus having the above-described configuration, when the second valve is closed, the supply of the cooling water to the water jacket of the cylinder block is stopped or the flow rate is limited. On the other hand, the cooling water is supplied to the water jacket of the cylinder head in a state where the flow rate is restricted by the flow restriction unit. Thereby, it is possible to avoid supplying cooling water in excess of the required flow rate to the water jacket of the cylinder head when the cooling water to the water jacket of the cylinder block is stopped or when the flow rate is restricted, and overcooling of the cylinder head can be suppressed. And a cylinder head can be warmed up effectively and it can contribute to the improvement of a fuel consumption. Moreover, since only one thermostat is used, the cost can be reduced as compared with the case where an electronically controlled flow control valve is used.

  In the engine cooling apparatus having the above-described configuration, it is preferable that supply of cooling water to the water jacket of the cylinder block is stopped when the second valve is closed.

  According to the engine cooling device having the above-described configuration, it is possible to promote the warm-up of the cylinder block with the second valve closed.

  In the engine cooling apparatus having the above-described configuration, it is preferable that the flow rate restriction portion is a through hole through which cooling water can flow.

  According to the engine cooling device having the above-described configuration, it is possible to limit the flow rate of the cooling water supplied to the water jacket of the cylinder head in the closed state of the second valve by restricting the flow rate of the cooling water through the through hole. .

  In the engine cooling apparatus configured as described above, the first valve and the second valve are operated in conjunction with each other according to the temperature of the cooling water, and when the second valve is open, the first valve is also opened. It is preferable to be in a valve state.

  According to the engine cooling apparatus having the above-described configuration, the thermostat can have a simple configuration by operating the first valve and the second valve in conjunction with each other.

  In the engine cooling apparatus having the above configuration, the valve opening direction of the first valve and the valve closing direction of the second valve are opposite to each other, and the pressure of the cooling water of the first valve is applied. The area is preferably larger than the area of the portion where the cooling water pressure of the second valve acts.

  According to the engine cooling apparatus having the above configuration, the area of the portion where the pressure of the cooling water of the first valve acts is larger than the area of the portion of the second valve where the pressure of the cooling water acts. When the discharge pressure of the water pump increases due to the increase in the pressure, the difference between the force in the valve opening direction of the first valve and the force in the valve closing direction of the second valve increases, and as a result, the second valve is opened. As a result, even if the engine speed rapidly increases, the second valve can be quickly opened, and the cooling water can be quickly supplied to the water jacket of the cylinder block. The situation where the cooling water boils can be avoided.

  In the engine cooling apparatus having the above-described configuration, a restriction relaxation unit that relaxes a restriction on a flow rate of the cooling water supplied to the water jacket of the cylinder head by the flow rate restriction unit when the second valve is opened is provided. preferable.

  According to the engine cooling apparatus configured as described above, when the first and second valves are opened, the cooling water is supplied to the water jacket of the cylinder block, and the flow rate of the first valve is supplied to the water jacket of the cylinder head. Not only the cooling water that has passed through the restriction part (through hole) but also the cooling water that has passed through the restriction relaxation part is supplied. This makes it possible to reliably supply the required flow rate of cooling water to the water jacket of the cylinder head, and to avoid a situation where the cooling water boils.

  In the engine cooling apparatus having the above-described configuration, it is preferable that the restriction relaxation portion is a diameter-expanded portion provided in the cooling water flow path.

  According to the engine cooling apparatus having the above-described configuration, the flow rate of the cooling water supplied to the water jacket of the cylinder head can be secured with the second valve opened by a simple configuration in which the diameter-enlarged portion is provided in the cooling water flow path. Is possible.

  According to the engine cooling device of the present invention, when the second valve is closed, the supply of the cooling water to the water jacket of the cylinder block is stopped or the flow rate is limited. On the other hand, the cooling water is supplied to the water jacket of the cylinder head in a state where the flow rate is restricted by the flow restriction unit. As a result, it is possible to avoid supplying cooling water exceeding the required flow rate to the water jacket of the cylinder head when the supply of cooling water to the water jacket of the cylinder block is stopped or when the flow rate is restricted, and overcooling of the cylinder head can be suppressed. . And a cylinder head can be warmed up effectively and it can contribute to the improvement of a fuel consumption. Moreover, since only one thermostat is used, the cost can be reduced as compared with the case where an electronically controlled flow control valve is used.

It is a figure showing typically the schematic structure of the cooling device of the engine concerning the embodiment of the present invention. It is sectional drawing which shows the cooling water flow path of the block thermostat and its peripheral part, Comprising: It is a figure which shows the valve closing state of the 1st valve and 2nd valve of a block thermostat. It is X1-X1 sectional drawing of FIG. It is a figure which shows the valve opening state of the 1st valve and 2nd valve of a block thermostat. It is X2-X2 sectional drawing of FIG.

  Embodiments of the present invention will be described with reference to the accompanying drawings.

  Below, the example which applied this invention to the cooling device of the engine which cools the engine mounted in vehicles, such as a motor vehicle, by circulation of cooling water is demonstrated.

  The engine cooling device illustrated in FIG. 1 includes an engine 10, a water pump 20, a radiator 30, a heater core 40, a radiator thermostat (first thermostat) 50, a block thermostat (second thermostat) 70, and these devices. A cooling water circuit 100 for circulating water (for example, LLC: Long Life Coolant) is provided.

  The engine 10 generates power in the vehicle by burning an air-fuel mixture of fuel and air. A cooling water passage is formed inside the engine 10, and the entire engine 10 is cooled by circulating the cooling water through the cooling water passage. Specifically, the engine 10 includes a cylinder head 11 and a cylinder block 12. Water jackets 11a and 12a are formed in the cylinder head 11 and the cylinder block 12 as cooling water passages, respectively. The water jacket 12 a of the cylinder block 12 is provided so as to surround the plurality of cylinders 13 formed in the cylinder block 12.

  Cooling water that has passed through the water jacket 11a of the cylinder head 11 flows into the radiator 30, the heater core 40, the radiator thermostat 50, and the like. Further, the cooling water that has passed through the water jacket 12 a of the cylinder block 12 flows into the flow path 11 b that communicates with the inlet side (upstream side) of the water jacket 11 a of the cylinder head 11.

  The water pump 20 is a mechanical water pump that is connected to a crankshaft that is an output shaft of the engine 10 and is driven by the rotation of the crankshaft as a power source. In this embodiment, the cooling water discharged by the water pump 20 can be supplied to each of the water jacket 11 a of the cylinder head 11 of the engine 10 and the water jacket 12 a of the cylinder block 12 after passing through the block thermostat 70. ing. The water pump 20 is disposed on the side of the cylinder block 12 of the engine 10. Although not shown, the water pump pulley provided on the drive shaft of the water pump 20 and the crank pulley provided on the crankshaft of the engine 10 are not shown. A transmission belt is stretched between them.

  The radiator 30 is, for example, a down flow type, and is configured to include a radiator core between an upper tank and a lower tank. The cooling water that has flowed into the upper tank of the radiator 30 exchanges heat with outside air (running wind or air blown by a cooling fan) when flowing down the radiator core toward the lower tank. And cooling water is cooled by radiating heat to the outside air.

  The heater core 40 is for heating the passenger compartment by exchanging heat between the cooling water and the conditioned air, and is disposed facing a blower duct of an air conditioner (not shown). That is, when heating the vehicle interior, the conditioned air flowing in the air duct is passed through the heater core 40 and supplied as warm air to the vehicle interior, while at other times (for example, during cooling), the heater core 40 is bypassed. Air conditioned air is sent into the passenger compartment.

  The radiator thermostat 50 is a wax-type thermostat that operates according to the temperature of the cooling water around the heat-sensitive portion (heat-sensitive cylinder) 54. Specifically, in the radiator thermostat 50, the valve (valve element) 51 is operated by the expansion and contraction of the thermowax filled in the thermal cylinder 54, similarly to the block thermostat 70 (see FIG. 2 and the like) described later. Is configured to do.

  The radiator thermostat 50 is provided between the outlet 32 of the radiator 30 and the suction port 21 of the water pump 20. The radiator thermostat 50 is configured such that the operation of the valve 51 causes the cooling water to circulate through the bypass passage 101 without passing through the radiator 30, and the state in which the cooling water circulates through the radiator 30. Can be switched to.

  The radiator thermostat 50 is provided with a first port 50a, a second port 50b, and a third port 50c. The first port 50 a is in communication with a flow path on the outlet 32 side (downstream side) of the radiator 30.

  The second port 50 b communicates with the bypass flow path 101 that bypasses the radiator 30. The bypass flow path 101 is branched from the flow path on the outlet side (downstream side) of the water jacket 11 a of the cylinder head 11 on the inlet 31 side (upstream side) of the radiator 30. A flow path 102 communicating with the inlet 41 side (upstream side) of the heater core 40 is branched from the flow path on the outlet side of the water jacket 11 a of the cylinder head 11 on the inlet 31 side (upstream side) of the radiator 30. . A flow path 103 communicating with the outlet 42 side (downstream side) of the heater core 40 is connected to the bypass flow path 101.

  The third port 50 c communicates with the flow path on the suction port 21 side (upstream side) of the water pump 20. In the thermostat 50 for the radiator, the second port 50b and the third port 50c are in communication. The first port 50 a and the third port 50 c are communicated or blocked by the operation of the valve 51.

  When the temperature of the cooling water is low, specifically, when the temperature of the cooling water around the thermal cylinder 54 is equal to or lower than a predetermined switching temperature, the thermostat 50 for the radiator Shrink. Along with this, the valve 51 is closed, and the first port 50a and the third port 50c are switched to a shut-off state. In this state, the cooling water is returned to the water pump 20 side via the bypass channel 101. In this way, the engine 10 is warmed up by not allowing the coolant to flow through the radiator 30.

  On the other hand, when the temperature of the cooling water around the thermal cylinder 54 rises and becomes higher than the switching temperature, the thermo wax in the thermal cylinder 54 expands. Accordingly, the valve 51 is opened, and the first port 50a and the third port 50c are switched to a communication state. In this state, the cooling water is returned to the water pump 20 side via the radiator 30. In this way, the cooling water is circulated through the radiator 30 so that the heat recovered by the cooling water is released from the radiator 30 to the atmosphere.

  The block thermostat 70 is a wax-type thermostat that operates according to the temperature of the cooling water around the heat-sensitive portion (heat-sensitive cylinder) 74. Specifically, the block thermostat 70 is configured such that the first valve 71 and the second valve 72 are operated by the expansion and contraction of the thermowax 75 filled in the thermal cylinder 74. The details of the block thermostat 70 will be described below with reference to FIGS.

  As shown in FIG. 2, the block thermostat 70 controls the first valve 71 that controls the flow rate of cooling water supplied to the water jacket 11 a of the cylinder head 11 and the flow rate of cooling water supplied to the water jacket 12 a of the cylinder block 12. And a second valve 72. The first and second valves 71 and 72 are provided to operate in conjunction with a common thermoactuator 73 that is driven according to the temperature of the cooling water. The first valve 71 is provided on one end side (left end side in FIG. 2) of the thermoactuator 73, and the second valve 72 is provided on the other end side (right end side in FIG. 2) of the thermoactuator 73. .

  Specifically, the thermoactuator 73 is a driving unit for detecting the temperature change of the cooling water to drive the first and second valves 71 and 72, and has a bottomed cylinder filled with a thermowax 75 inside. A heat-sensitive cylinder 74 having a shape is provided. The first valve 71 is attached to the bottom side of the thermal cylinder 74, and the second valve 72 is attached to the opening side of the thermal cylinder 74. A cylindrical cover member 76 is attached to the opening of the thermal cylinder 74. One end side of the push rod 77 is inserted into the thermal cylinder 74, and the other end side of the push rod 77 protrudes from the center hole of the guide member 76 to the outside of the thermal cylinder 74. The thermo wax 75 is filled in a space between the elastic seal spool 78 attached to the inner side surface of the guide member 76 and the inner wall surface of the thermal cylinder 74. The thermowax 75 changes into a state that solidifies and contracts or a state that melts and expands depending on the temperature, and generally known ones (for example, paraffin wax) can be used.

  The thermoactuator 73 is attached to the first and second frames 81 and 82 that are coupled to each other. The first and second frames 81 and 82 have a shape that does not hinder the flow of cooling water. A protruding end (right end in FIG. 2) of the push rod 77 is fixed at the center of the second frame 82, and the thermal cylinder 74 is supported so as to be relatively displaceable with respect to the first frame 81.

  A return spring 83 is interposed between the second valve 72 and the first frame 81 in a compressed state. The elastic force of the return spring 83 acts in a direction in which the second valve 72 is pressed against the annular flange portion 82a of the second frame 82 to close the inner hole of the annular flange portion 82a. The return spring 83 urges the first and second valves 71 and 72 in a direction to close the valve.

  In the block thermostat 70, the flow path on the discharge port 22 side (downstream side) of the water pump 20 has an inlet side (upstream side) of the water jacket 11a of the cylinder head 11 and an inlet side of the water jacket 12a of the cylinder block 12 ( (Upstream side) In this embodiment, the block thermostat 70 is disposed inside the cylinder block 12 at a portion communicating with the inlet side of the water jacket 12a.

  The block thermostat 70 is provided with a first port 70a, a second port 70b, and a third port 70c. The first port 70 a communicates with the flow path on the discharge port 22 side (downstream side) of the water pump 20.

  The second port 70 b communicates with the cooling water passage 11 b on the inlet side of the water jacket 11 a of the cylinder head 11. A first valve 71 is disposed in the second port 70b. The first valve 71 is formed in a substantially disc shape, and a rubber 71 a is attached to the outer periphery of the first valve 71. The rubber 71a enhances the adhesion between the first valve 71 and the inner wall surface of the second port 70b (cooling water channel 71b). The area of the portion of the first valve 71 where the cooling water pressure acts is larger than the area of the portion of the second valve 72 where the cooling water pressure acts.

  The first valve 71 is provided with a plurality of through holes 71c, 71c,. Therefore, even when the first valve 71 is closed (the state shown in FIGS. 2 and 3), the first port 70a and the second port 70b communicate with each other through the through holes 71c, 71c,. As shown by a two-dot chain line A1 in FIG. 2, the cooling water is supplied to the water jacket 11a of the cylinder head 11 through the through holes 71c, 71c,. The flow passage cross-sectional areas of the through holes 71c, 71c,... Are set to values that can effectively warm up the cylinder head 11 when the second valve 72 is closed (the state shown in FIG. 2). It is possible.

  Further, the first valve 71 is provided with an enlarged diameter portion (large diameter portion) 71d in the cooling water flow path 71b. The enlarged diameter portion 71d is a recess in which the inner wall surface of the cooling water channel 71b is recessed toward the outer diameter side from the front and rear portions. Therefore, when the first valve 71 is in the open state (the state shown in FIGS. 4 and 5), the first port 70a and the second port 70b are connected to the through holes 71c, 71c,. As shown by two-dot chain lines A1, A2 in FIG. 4, cooling water is supplied to the water jacket 11a of the cylinder head 11 through the through holes 71c, 71c,. Is to be supplied. The enlarged diameter portion 71 d may be formed on the inner wall surface of the cooling water flow path inside the cylinder block 12, or may be formed on the inner wall surface of the pipe attached to the cylinder block 12. The channel cross-sectional area of the enlarged diameter portion 71d can be set to a value that can effectively cool the cylinder head 11 when the second valve 72 is opened (the state shown in FIG. 4).

  The third port 70 c communicates with the inlet side of the water jacket 12 a of the cylinder block 12. A second valve 72, a second frame 82, and the like are arranged in the third port 70c. A rubber 72 a is attached to the outer peripheral portion of the second valve 72, and adhesion between the second valve 72 and the annular flange portion 82 a of the second frame 82 is enhanced by the rubber 72 a.

  When the second valve 72 is in the closed state (the state shown in FIG. 2), the second valve 72 and the annular flange portion 82a of the second frame 82 are in close contact with each other, and the first port 70a and the third port The port 70c is blocked. For this reason, the cooling water is not supplied to the water jacket 12 a of the cylinder block 12.

  On the other hand, in the valve open state of the second valve 72 (the state shown in FIG. 4), the second valve 72 and the annular flange portion 82a of the second frame 82 are separated from each other, and the first port 70a and the third port The port 70c communicates with the port 70c. Therefore, as shown by a one-dot chain line B2 in FIG. 4, the cooling water is supplied to the water jacket 12a of the cylinder block 12 through the gap between the second valve 72 and the annular flange portion 82a of the second frame 82. It has become.

  In this embodiment, the first and second valves 71 and 72 of the block thermostat 70 are provided so as to be integrally operated by a thermoactuator 73. The operation of the block thermostat 70 will be described with reference to FIGS.

  First, as shown in FIG. 2, when the protrusion amount L1 of the push rod 77 from the thermosensitive cylinder 74 (guide member 76) is minimum, the first valve 71 is the inner wall surface of the second port 70b (cooling water flow path 71b). The first valve 71 is in a closed state. In the closed state of the first valve 71, as shown by a two-dot chain line A1 in FIG. 2, the cooling water is supplied to the water jacket 11a of the cylinder head 11 through the through holes 71c, 71c,. The second valve 72 is in close contact with the annular flange portion 82a of the second frame 82, and the second valve 72 is in a closed state. In the closed state of the second valve 72, the supply of cooling water to the water jacket 12a of the cylinder block 12 is stopped (in-block water stop).

  Next, from the state shown in FIG. 2, the protrusion L1 of the push rod 77 from the thermal cylinder 74 (guide member 76) increases, so that the second valve 72 resists the elastic force of the return spring 83 and the annular flange. Move away from the part 82a. As shown in FIG. 4, when the protrusion amount L1 of the push rod 77 becomes maximum, the second valve 72 is completely separated from the annular flange portion 82a, and the second valve 72 is opened. . Moreover, when the 1st valve 71 moves toward the diameter expansion part 71d side of the cooling water flow path 71b and the protrusion amount L1 of the push rod 77 becomes the maximum as shown in FIG. 4, the 1st valve 71 is cooled. It will be in the state located in the enlarged diameter part 71d completely away from the inner wall face of the water flow path 71b, and the 1st valve 71 will be in a valve opening state.

  On the other hand, from the state shown in FIG. 4, the protrusion amount L1 of the push rod 77 from the thermosensitive cylinder 74 (guide member 76) decreases, whereby the second valve 72 approaches the annular flange portion 82a by the elastic force of the return spring 83. Move in the direction. Then, as shown in FIG. 2, when the protrusion amount L1 of the push rod 77 is minimized, the second valve 72 is in close contact with the annular flange portion 82a, and the second valve 72 is closed. . Further, the first valve 71 moves toward the upstream side (right side in FIG. 2) of the enlarged diameter portion 71d of the cooling water passage 71b, and as shown in FIG. 2, the protrusion amount L1 of the push rod 77 is minimized. When it becomes, the 1st valve 71 will be in the state closely_contact | adhered to the inner wall face of the cooling water flow path 71b, and the 1st valve 71 will be in a valve closing state.

  Here, as a factor for changing the protrusion amount L1 of the push rod 77, in other words, a factor for switching between the open state and the closed state of the first and second valves 71 and 72, the rotational speed of the engine 10 and the load And the temperature of the cooling water fluctuates, and the rotation speed of the engine 10 fluctuates and the discharge pressure of the water pump 20 fluctuates. When the temperature of the cooling water rises with an increase in the rotational speed and load of the engine 10, the thermowax 75 expands and as a result, the protrusion amount L1 of the push rod 77 is increased. On the contrary, when the temperature of the cooling water decreases with a decrease in the rotational speed or load of the engine 10, the thermowax 75 contracts, so that the protrusion amount L1 of the push rod 77 is decreased.

  Further, as described above, since the area of the portion of the first valve 71 where the cooling water pressure acts is larger than the area of the portion of the second valve 72 where the cooling water pressure acts, the first and second valves The force acting in the valve opening direction (left direction in FIG. 4) of the first valve 71 is the force acting in the valve closing direction (right direction in FIG. 4) of the first valve 71 by the area difference between 71 and 72. Also grows. Since the valve opening direction of the first valve 71 and the valve closing direction of the second valve 72 are opposite to each other, if the discharge pressure of the water pump 20 increases due to an increase in the rotational speed of the engine 10, the opening of the first valve 71 As a result of an increase in the difference between the force in the valve direction and the force in the valve closing direction of the second valve, the protrusion amount L1 of the push rod 77 is increased. On the contrary, if the discharge pressure of the water pump 20 is reduced due to the decrease in the rotational speed of the engine 10, the difference between the force in the valve opening direction of the first valve 71 and the force in the valve closing direction of the second valve becomes smaller. The protrusion amount L1 of the rod 77 is reduced.

  In this embodiment, when the second valve 72 is closed, the through holes 71c, 71c,... As flow restricting portions that restrict (squeeze) the cooling water flow supplied to the water jacket 11a of the cylinder head 11 are provided. The first valve 71 is provided. Thereby, the following effects are obtained.

  In the closed state of the second valve 72, the supply of the cooling water to the water jacket 12a of the cylinder block 12 is stopped (water in the block is stopped). On the other hand, only the cooling water that has passed through the through holes 71c, 71c,... Of the first valve 71 is supplied to the water jacket 11a of the cylinder head 11 as indicated by a two-dot chain line A1 in FIG. That is, the cooling water is supplied to the water jacket 11a of the cylinder head 11 in a state where the flow rate is limited by the through holes 71c, 71c,. As a result, it is possible to avoid supplying cooling water of a required flow rate or higher to the water jacket 11a of the cylinder head 11 when the water in the block is stopped, and to suppress overcooling of the cylinder head 11. And the cylinder head 11 can be warmed up effectively, and it can contribute to the improvement of fuel consumption. Moreover, since only one block thermostat 70 is used, the cost can be reduced as compared with the case where an electronically controlled flow control valve is used.

  Moreover, in this embodiment, as the restriction relaxation part which eases restriction | limiting of the flow volume of the cooling water supplied to the water jacket 11a of the cylinder head 11 by the through-holes 71c, 71c, ... with the 2nd valve 72 opened. An enlarged diameter portion 71 d is provided in the first valve 71. Here, if the enlarged diameter portion 71d is not provided, even if the first and second valves 71 and 72 are opened at the time of high rotation of the engine 10 with severe heat load, the water jacket of the cylinder head 11 is used. Only the cooling water that has passed through the through holes 71c, 71c,... Of the first valve 71 is supplied to 11a. For this reason, there is a possibility that the cooling water of the required flow rate cannot be supplied to the water jacket 11a of the cylinder head 11 and the cooling water boils.

  However, in this embodiment, when the first and second valves 71 and 72 are opened, cooling water is supplied to the water jacket 12a of the cylinder block 12, and the water jacket 11a of the cylinder head 11 In addition to the cooling water that has passed through the through holes 71c, 71c,... Of the one valve 71, the cooling water that has passed through the enlarged diameter portion 71d is also supplied as indicated by a two-dot chain line A2 in FIG. That is, the flow rate of the cooling water to the water jacket 11a of the cylinder head 11 by the through holes 71c, 71c,... Is limited by the increase in the flow rate of the cooling water to the water jacket 11a of the cylinder head 11 passing through the enlarged diameter portion 71d. Is alleviated. As a result, for example, when the engine 10 is rotating at a high speed or when the engine is rotating at a low speed and a high load, the required amount of cooling water can be reliably supplied to the water jacket 11a of the cylinder head 11, and the cooling water will boil. You can avoid the situation.

  In this embodiment, the valve opening direction of the first valve 71 and the valve closing direction of the second valve 72 are opposite to each other, and the area of the portion of the first valve 71 on which the pressure of the cooling water acts is the same. The area of the portion where the pressure of the cooling water of the second valve 72 acts is larger. Here, if the area of the portion where the pressure of the cooling water acts on the first valve 71 is equal to or smaller than the area of the portion where the pressure of the cooling water acts on the second valve 72, even if the engine speed increases. If the temperature of the cooling water around the thermal cylinder 74 rises and the thermowax 75 does not expand, the second valve 72 does not open. For this reason, when the rotational speed of the engine 10 suddenly increases immediately before the second valve 72 is opened, the thermowax 75 expands until the second valve 72 is opened. There is a possibility that the temperature will rise rapidly and the cooling water will boil.

  However, in this embodiment, the area of the portion where the pressure of the cooling water acts on the first valve 71 is larger than the area of the portion where the pressure of the cooling water acts on the second valve 72. When the discharge pressure of the water pump 20 increases due to the rise, the difference between the force in the valve opening direction of the first valve 71 and the force in the valve closing direction of the second valve increases. As a result, the protrusion amount L1 of the push rod 77 is increased, the second valve 72 is opened, and the annular flange portion 82a of the second valve 72 and the second frame 82 as shown by a one-dot chain line B2 in FIG. The cooling water that has passed through the gap is supplied to the water jacket 12 a of the cylinder block 12. Thereby, even if the rotation speed of the engine 10 suddenly increases, the second valve 72 can be quickly opened, and the cooling water can be quickly supplied to the water jacket 12a of the cylinder block 12. The situation where the cooling water boils can be avoided.

-Other embodiments-
The present invention is not limited only to the above-described embodiments, and all modifications and applications within the scope of the claims and within the scope equivalent to the scope are possible.

  The cooling water circuit 100 described above is an example, and any configuration is possible as long as the cooling water discharged by the water pump 20 can be supplied to each of the water jacket 11a of the cylinder head 11 and the water jacket 12a of the cylinder block 12. There may be. For example, in the above embodiment, the cooling water that has passed through the water jacket 12 a of the cylinder block 12 is caused to flow into the water jacket 11 a of the cylinder head 11, but the cooling water that has passed through the water jacket 12 a of the cylinder block 12 It is good also as a structure made to flow into the radiator 30 grade | etc., Without making it flow in into the water jacket 11a.

  In the above embodiment, the block thermostat 70 is arranged inside the cylinder block 12, but the block thermostat 70 may be arranged outside the cylinder block 12.

  In the above embodiment, the supply of the cooling water to the water jacket 12a of the cylinder block 12 is stopped when the second valve 72 of the block thermostat 70 is closed. However, the cooling water is stopped when the second valve 72 is closed. It is also possible to supply the cooling water to the water jacket 12a of the cylinder block 12 by restricting the flow rate. In addition, it becomes possible to aim at warming-up promotion of the cylinder block 12 by stopping water in a block like the said embodiment.

  The above-described through hole 71c provided in the first valve 71 is an example of a flow rate restricting unit, and may have any configuration as long as the flow rate of cooling water supplied to the water jacket 11a of the cylinder head 11 can be limited. . For example, the flow restricting portion can be configured by forming the first valve 71 with a small diameter or by forming a notch or the like on the outer peripheral portion of the first valve 71. As in the above embodiment, if the flow restricting portion is the through hole 71c, the flow rate of the cooling water is reduced by the through hole 71c, so that the second valve 72 is closed and the water jacket 11a of the cylinder head 11 is closed. It becomes possible to limit the flow rate of the cooling water to be supplied.

  The diameter-expanded portion 71d is an example of a restriction relaxing portion, and may have any configuration as long as the restriction on the flow rate of cooling water supplied to the water jacket 11a of the cylinder head 11 by the flow restriction portion can be relaxed. . As in the above embodiment, if the restriction relaxing portion is configured by the enlarged diameter portion 71d, the cylinder head can be opened with the second valve 72 opened by a simple configuration in which the enlarged diameter portion 71d is provided in the cooling water flow path. Thus, it is possible to secure the flow rate of the cooling water supplied to the 11 water jackets 11a.

  In the above embodiment, the first and second valves 71 and 72 of the block thermostat 70 are operated in conjunction with each other. However, the first and second valves 71 and 72 may be operated separately. If the first and second valves 71 and 72 are operated in conjunction with the thermoactuator 73 as in the above embodiment, the block thermostat 70 can have a simple configuration.

  INDUSTRIAL APPLICABILITY The present invention can be used for an engine cooling device configured to be able to supply cooling water discharged by a water pump to each of a water jacket of a cylinder head and a water jacket of a cylinder block.

DESCRIPTION OF SYMBOLS 10 Engine 11 Cylinder head 11a Water jacket 12 Cylinder block 12a Water jacket 20 Water pump 70 Thermostat 71 for block 71 1st valve 71c Through-hole (flow restriction part)
71d Diameter expansion part (restriction alleviation part)
72 Second valve 73 Thermoactuator 74 Thermosensitive cylinder 75 Thermowax

Claims (7)

An engine cooling device configured to be able to supply cooling water discharged by a water pump to each of a water jacket of a cylinder head and a water jacket of a cylinder block,
A thermostat having a first valve for controlling a flow rate of cooling water supplied to the water jacket of the cylinder head and a second valve for controlling a flow rate of cooling water supplied to the water jacket of the cylinder block;
The engine cooling device according to claim 1, wherein the first valve is provided with a flow rate limiting unit that limits a flow rate of cooling water supplied to the water jacket of the cylinder head when the second valve is closed. The engine cooling device according to claim 1,
The engine cooling apparatus according to claim 1, wherein when the second valve is closed, the supply of cooling water to the water jacket of the cylinder block is stopped. The engine cooling device according to claim 1 or 2,
The engine cooling device according to claim 1, wherein the flow restriction unit is a through hole through which cooling water can flow. The engine cooling device according to any one of claims 1 to 3,
The first valve and the second valve are operated in accordance with the temperature of the cooling water, and when the second valve is open, the first valve is also opened. Engine cooling system. The engine cooling device according to claim 4,
The valve opening direction of the first valve and the valve closing direction of the second valve are opposite to each other,
The engine cooling device according to claim 1, wherein an area of the portion of the first valve where the pressure of the cooling water acts is larger than an area of the portion of the second valve where the pressure of the cooling water acts. In the engine cooling device according to any one of claims 1 to 5,
An engine cooling apparatus, comprising: a restriction relaxation unit that relaxes a restriction on a flow rate of cooling water supplied to the water jacket of the cylinder head by the flow rate restriction unit when the second valve is opened. The engine cooling device according to claim 6,
The engine cooling apparatus according to claim 1, wherein the restriction relaxation portion is a diameter-expanded portion provided in the cooling water flow path.

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