JP2006242073A - Cooling device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve warming up performance of an engine by limiting flow rate of cooling water circulating a water jacket during cold state and preventing circulation of cooling water to a cabin heater passage. <P>SOLUTION: This device is provided with a radiator passage 81, a radiator bypass passage 84, a cabin heater passage 82, a water jacket bypass passage 85, a thermostat valve 43c closing the radiator passage 81 when cooling water temperature is less than predetermined first temperature, a temperature control valve 7 closing the cabin heater passage 82 and opening the water jacket bypass passage 85 when cooling water temperature is less than predetermined second temperature and opening the cabin heater passage 82 and closing the water jacket bypass passage 85 when cooling water temperature is not less than predetermined second temperature, a pressure relief valve 43g provided in the radiator bypass passage 84. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an engine cooling apparatus.

  Generally, an engine is designed to operate with desired performance within a predetermined temperature range. Therefore, when the engine is warm, the engine is cooled with cooling water so that the engine temperature is within the predetermined temperature range. Yes. This cooling water circulates in the water jacket formed in the cylinder head and cylinder block, receives heat from the cylinder head and cylinder block by heat exchange, and exchanges heat with a radiator and a cabin heater for warming the passenger compartment. The amount of cooling water is released.

  Further, as described above, the engine needs to be cooled when warm, while the engine needs to be warmed up early when cold. That is, when the engine is in a low temperature state below the predetermined temperature range, the fuel is difficult to vaporize, difficult to ignite, or the combustion speed is slow. Further, for example, since the clearance between the cylinder and the piston is too large, the air-fuel mixture and the combustion gas are easily blown from between the cylinder and the piston. Therefore, conventionally, a device for warming up the engine early using engine coolant that circulates through the cylinder head, the cylinder block, and the like has been devised.

  For example, the engine cooling device disclosed in Patent Document 1 includes a radiator passage, a radiator bypass passage, a cabin heater passage, and the like as passages when cooling water that has flowed out of the water jacket returns to the water pump. The warm-up performance is improved by changing the distribution passage accordingly. The radiator passage is a passage through which the cooling water flows when the cooling water temperature is equal to or higher than a predetermined temperature, and a radiator is interposed in the middle, and the engine is cooled by cooling the cooling water by the radiator. Is the passage. The radiator bypass passage is a passage through which the cooling water flows when the cooling water is below a predetermined temperature. By bypassing the radiator, the cooling water itself is not cooled so that the engine body can be warmed up early. It is a passage for performing. The cabin heater passage is provided with a cabin heater unit that warms the passenger compartment along the way, and is used to warm the passenger compartment by the amount of heat of the cooling water. As long as the cooling water is in circulation. The cabin heater passage has a cabin heater return passage for connecting the cabin heater unit and the water pump, and a downstream portion thereof is formed inside the cylinder block, thereby reducing the size of the engine and the cooling water passage. Is shortened. As described above, the engine cooling apparatus according to Patent Document 1 cools the engine by circulating the radiator through the cooling water when the cooling water temperature is equal to or higher than the predetermined temperature, while the cooling water temperature is the predetermined temperature. When the engine is cold, the engine is warmed up early by diverting the radiator to the coolant.

  However, the engine cooling device according to Patent Document 1 has room for further improvement in its warm-up performance. Although the engine cooling device according to Patent Document 1 bypasses the radiator in the cooling water when it is cold, the cooling water is circulated in the radiator bypass passage and the cabin heater passage. The amount of heat is actively transferred from the engine body to the cooling water. Even if the cooling water is not cooled by the radiator, the amount of heat of the cooling water is used to warm the passenger compartment by the cabin heater in the cabin heater passage, or escapes to the outside during circulation through the radiator bypass passage. There is a case.

As an improvement measure, there is an engine cooling device disclosed in Patent Document 2. The engine cooling device disclosed in Patent Document 2 further includes a water jacket bypass passage in addition to the engine cooling device passage disclosed in Patent Document 1 as a passage for circulating cooling water. This water jacket bypass passage is a passage that causes the water jacket to be shortcutted to the coolant discharged from the water pump and returns it to the water pump, and an electromagnetic valve for opening and closing the water jacket bypass passage is provided in the passage. Yes. The cooling device according to Patent Document 2 opens the electromagnetic valve so that the cooling water flows through the water jacket bypass passage when the cooling water temperature is lower than a predetermined temperature that is lower than the predetermined temperature that opens the radiator bypass passage. On the other hand, when the cooling water temperature is equal to or higher than a predetermined temperature, the solenoid valve is closed so that the cooling water flows through the cabin heater passage and the radiator bypass passage or the radiator passage. That is, when the engine is cold, the water jacket of the engine body is bypassed to the cooling water so that heat exchange is not actively performed between the cylinder head and the cylinder block and the cooling water. As a result, the engine is warmed up early.
JP 2001-115836 A JP 2004-301032 A

  However, the engine cooling device disclosed in Patent Document 2 is configured such that no cooling water flows through the radiator bypass passage or the cabin heater passage when the cooling water flows through the water jacket bypass passage. Do not mean. That is, the cooling device according to Patent Document 2 only opens the electromagnetic valve in the water jacket bypass passage when it is cold, and does not close the radiator bypass passage and the cabin heater passage. And since the flow resistance of a water jacket bypass passage is smaller than the flow resistance of a radiator bypass passage or a cabin heater passage, it is constituted so that most cooling water may circulate through a water jacket bypass passage. That is, when the protrusion pressure of the cooling water from the water pump increases, the cooling water may flow not only to the water jacket bypass passage but also to the radiator bypass passage and the cabin heater passage. As described above, in order to warm up the engine at an early stage, it is preferable that the coolant passage is not allowed to flow through the radiator passage and the radiator bypass passage and the cabin heater passage. In particular, if the cooling water flows through the cabin heater passage when the cabin heater is on, the amount of heat used for the cooling water is used to increase the temperature in the passenger compartment, which prevents early engine warm-up. In addition, even when cooling water flows through the cabin heater when the water temperature is low, the passenger feels uncomfortable just by blowing cool air from the cabin heater, so rather the circulation of the cooling water to the cabin heater is stopped and the engine It is more preferable as a heating function that the warm air can be quickly blown from the cabin heater by warming up the engine early.

  The present invention has been made in view of such a point, and an object of the present invention is to suppress the flow rate of the cooling water flowing through the water jacket when cold and prevent the cooling water from flowing through the cabin heater passage. The purpose is to improve the warm-up performance of the engine.

  The present invention provides a water jacket bypass passage for causing the water jacket to shortcut the cooling water, and allows the cooling water to flow through the water jacket bypass passage and the cooling water to flow through the cabin heater passage when cold. The warm-up performance is improved by preventing the above. Further, when the water pressure of the cooling water rises at this time, the cooling water flows through the radiator bypass passage to prevent an excessive increase in the water pressure of the cooling water.

  A first invention includes a water jacket formed in a cylinder block and a cylinder head, and a radiator passage in which a radiator is interposed, and the water pump is connected to the water jacket via the water jacket and the radiator passage. A cooling water circulation passage that returns to the pump, a radiator bypass passage that is provided in the middle of the cooling water circulation passage, bypasses the radiator, and a cabin heater passage that is provided in parallel with the radiator passage and in which a cabin heater unit is interposed. And a thermostat valve that closes the radiator passage when the cooling water temperature is lower than a predetermined first temperature.

  The upstream end is connected to the upstream side of the water jacket, while the downstream end is joined and connected to the cabin heater return passage that forms the downstream side of the cabin heater unit in the cabin heater passage. Provided at the junction of the water jacket bypass passage, the cabin heater return passage, and the water jacket bypass passage, and the cabin when the cooling water temperature is lower than a predetermined second temperature lower than the predetermined first temperature. A temperature control valve that closes the heater passage and opens the water jacket bypass passage, and opens the cabin heater passage and closes the water jacket bypass passage when the coolant temperature is equal to or higher than the predetermined second temperature; and the radiator bypass Cooling water provided in the passage Shall water pressure is further provided with a pressure relief valve that opens the radiator bypass passage when it becomes equal to or higher than a predetermined water pressure.

  In the case of the above configuration, the cooling water temperature will be described. When the cooling water temperature is lower than the predetermined second temperature, the radiator passage is closed by the thermostat valve and the cabin heater is closed by the temperature control valve. By closing the passage and opening the water jacket bypass passage, the cooling water does not flow into the radiator passage and the cabin heater passage, but flows through the water jacket bypass passage. Further, since the pressure relief valve is closed when the cooling water pressure is lower than the predetermined water pressure, the cooling water does not flow into the radiator bypass passage. As a result, when the cooling water temperature is lower than the predetermined second temperature and the water pressure of the cooling water is lower than the predetermined water pressure, the amount of heat of the cooling water is radiated by the radiator, and the amount of heat of the cooling water is generated by the cabin heater. It is possible to prevent the amount of heat of the cooling water from leaking to the outside during use of the vehicle interior and circulation of the radiator bypass passage. Further, the cooling water flows through the water jacket bypass passage, so that the flow rate of the cooling water flowing through the water jacket can be reduced and the engine can be warmed up early.

  Here, if the radiator passage, the cabin heater passage, and the radiator bypass passage are completely closed, there is a risk that hoses constituting each passage may come off when the coolant pressure increases. Therefore, in the present invention, when the water pressure of the cooling water rises and becomes equal to or higher than the predetermined water pressure, the pressure relief valve that has closed the radiator bypass passage is opened, and the cooling water is also circulated through the radiator bypass passage. As a result, it is possible to prevent the water pressure of the cooling water from becoming too high, and to prevent the hoses constituting the respective passages from coming off due to the increase in the water pressure of the cooling water. Since this pressure relief valve is provided in the radiator bypass passage, the passage through which the cooling water flows is the radiator bypass passage even if the pressure relief valve is opened to reduce the cooling water pressure. The amount of heat is not dissipated by the radiator and is not used to warm the passenger compartment by the cabin heater, and the temperature drop of the cooling water can be suppressed as much as possible.

  Next, when the cooling water temperature is equal to or higher than the predetermined second temperature and lower than the predetermined first temperature, the radiator passage is closed by the thermostat valve, the cabin heater passage is opened by the temperature control valve, and the By closing the water jacket bypass passage, the cooling water does not flow through the radiator passage and the water jacket bypass passage, but flows through the cabin heater passage. As a result, when the cooling water temperature is equal to or higher than the predetermined second temperature and lower than the predetermined first temperature, the amount of heat of the cooling water is not radiated by the radiator, and the temperature rise in the cabin by the cabin heater, the cylinder head and the cylinder By using for warming up a block or the like, warming of the passenger compartment and warming up of the engine can be performed at an early stage.

  Subsequently, when the cooling water temperature is equal to or higher than the predetermined first temperature, the radiator passage is opened by the thermostat valve, the cabin heater passage is opened by the temperature control valve, and the water jacket bypass passage is closed. The cooling water does not flow through the water jacket bypass passage but flows through the radiator passage and the cabin heater passage. As a result, when the cooling water temperature is equal to or higher than the predetermined first temperature, the amount of heat of the cooling water is used for warming the passenger compartment by the cabin heater, and is radiated by the radiator through the cooling water. Warming and engine cooling can be performed.

  That is, the predetermined second temperature is a temperature at which the engine warm-up should be prioritized over the warming of the passenger compartment, and the predetermined first temperature does not require the engine to be warmed up. It is better to set the temperature to be better.

  Therefore, by providing the temperature control valve at the junction of the cabin heater return passage and the water jacket bypass passage, the thermostat valve in the radiator passage, and the pressure relief valve in the radiator bypass passage, When the temperature is lower than the predetermined second temperature, the engine can be warmed up at an early stage by preventing the cooling water from flowing through the cabin heater passage while making the cooling water shortcut. At this time, if the water pressure of the cooling water becomes equal to or higher than the predetermined water pressure, the pressure relief valve opens and the cooling water flows to the radiator bypass passage, so that the water pressure of the cooling water can be prevented from rising excessively. As a result, it is possible to prevent the hoses constituting each passage from coming off. Further, the present invention does not realize early warm-up of the engine by controlling the discharge amount of the cooling water from the water pump, but changes the flow path of the cooling water according to the cooling water temperature. Since warming-up is realized, a mechanically driven water pump can be employed, and the cost of the cooling device can be reduced.

  A second aspect of the present invention is the intake system cooling water passage provided in parallel with the radiator passage and the cabin heater passage in the first aspect, wherein the cooling water is circulated through a wall of the intake passage for introducing intake air into the engine. And at least one of a cooling water heating device that raises the temperature of the cooling water when cold and an oil-water heat exchanger that performs heat exchange between the cooling water and the oil are disposed in the intake system cooling water passage. It shall be.

  In the case of the above configuration, the cooling water flows through the intake system cooling water passage regardless of the temperature of the cooling water. Therefore, as long as the water pump operates, the cooling water flows through the cooling water heating device and / or the oil-water heat exchanger provided in the intake system cooling water passage. Therefore, the cooling water can be heated by the cooling water heating device at an early time when the engine is cold, and the engine can be warmed up at an early stage. Sometimes the oil can be cooled by cooling water.

  According to a third invention, in the first or second invention, a water pump housing of the water pump is formed on one side of the front portion of the cylinder block, and the other side wall of the front portion of the cylinder block is formed on the side wall. The temperature control valve mounting seat is formed, and the cabin heater return passage includes an upstream portion of the cabin heater return passage upstream of the temperature control valve and a cabin heater return downstream of the temperature control valve. A downstream portion of the cabin heater, the downstream portion of the cabin heater return passage is configured such that, at the front portion of the cylinder block, an upstream end opens to a lower portion of the mounting seat, and a downstream end communicates with the water pump housing. The water jacket bypass passage is formed in the cylinder block front portion. While the upstream end connected to the upstream side of the water jacket, it is assumed that the downstream end is formed in the cylinder block so as to open the upper part of the attachment seat.

  The temperature control valve is attached to the mounting seat and communicates with the cabin heater return passage, the water jacket bypass passage, and the upstream portion of the cabin heater return passage, and the temperature control valve housing. A state in which the upstream portion of the cabin heater return passage and the downstream portion of the cabin heater return passage communicate with each other, the water jacket bypass passage and the downstream portion of the cabin heater return passage, There is a passage switching valve body that can switch between the state in which the two are connected, and a temperature sensing body that moves the passage switching valve body up and down according to the temperature.

  In the case of the above configuration, the water jacket bypass passage and the downstream portion of the cabin heater return passage are incorporated in the cylinder block, and the downstream end of the water jacket bypass passage and the upstream end of the downstream portion of the cabin heater return passage are respectively attached to the cylinder block. Since the temperature control valve housing that communicates with the cabin heater return passage, the water jacket bypass passage, and the upstream portion of the cabin heater return passage is attached to the mounting seat, A temperature control valve can be disposed at the junction of the cabin heater return passage and the water jacket bypass passage. That is, the temperature control valve can be easily arranged and attached. In addition, by adopting a thermostat system in which the temperature control valve is operated by the temperature sensing element, switching between the cabin heater passage and the water jacket bypass passage according to the cooling water temperature is performed by electrically controlling the solenoid valve or the like. There is no need to do this, and it can be realized at low cost.

  According to a fourth aspect, in the third aspect, a thermostat housing that communicates with the water pump and incorporates the thermostat valve is formed on one side wall of the front portion of the cylinder block where the water pump housing is formed. The downstream end of the radiator passage is pipe-connected to the thermostat housing, and the radiator bypass passage is formed in the side wall on the one side of the cylinder block, and the cylinder block of the thermostat housing It is assumed that the thermostat valve is opened inward, and the thermostat valve is configured integrally with a pressure relief valve that opens and closes the opening of the radiator bypass passage.

  In the case of the above configuration, by forming in the side wall of the cylinder block of the radiator bypass passage, even if the coolant pressure rises and the coolant flows through the radiator bypass passage, the coolant bypass passage from the coolant Since the amount of heat transmitted to the passage wall is conducted not to the outside air but to the cylinder block, it is possible to warm up the engine early by suppressing the amount of heat of the cooling water to be radiated to the outside as much as possible. In addition, by forming the radiator bypass passage in the side wall of the cylinder block, the complexity of piping the radiator bypass passage to the outside with respect to the engine body can be eliminated, and the passage length can be shortened. . Furthermore, since the thermostat valve and the pressure relief valve are integrally formed, and the radiator passage and the radiator bypass passage are connected to the thermostat housing, the passage arrangement of these is facilitated, and the thermostat valve and the pressure relief valve Assembly workability can be improved.

  According to the present invention, the temperature at which the cabin heater passage is closed and the water jacket bypass passage is opened when the coolant temperature is lower than a predetermined second temperature at the junction of the cabin heater return passage and the water jacket bypass passage. A control valve, a thermostat valve for closing the radiator passage when the coolant temperature is lower than a predetermined first temperature higher than the predetermined second temperature, and a water pressure of the cooling water for the radiator bypass passage. By providing a pressure relief valve that opens the radiator bypass passage when the water pressure becomes equal to or higher than a predetermined water pressure, when the cooling water temperature is lower than the predetermined second temperature, the cooling water is shortcut to the water jacket. Prevents cooling water from flowing into the cabin heater passage and It is possible to warm up to. At this time, if the water pressure of the cooling water becomes equal to or higher than the predetermined water pressure, the pressure relief valve opens and the cooling water flows to the radiator bypass passage. Therefore, even if the radiator passage and the cabin heater passage are closed, the cooling water As a result, it is possible to prevent the hose constituting each passage from coming off.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic configuration of a cooling device for an engine E according to an embodiment of the present invention. Reference numeral 1 denotes an engine body including a cylinder head 2 and a cylinder block 3 made of an aluminum alloy, and reference numeral 51 denotes an engine E. A radiator 52 is provided at the front of the vehicle for cooling the coolant of the engine E. Reference numeral 52 is a cabin heater 52 provided at the rear of the engine E for heating the vehicle interior. The engine E is an in-line four-cylinder gasoline engine in which four cylinders 19 (provided in the cylinder block 3) are arranged in series in the direction in which the crankshaft extends.

  This engine E is mounted horizontally in the engine room of the vehicle so that the cylinder row direction in which the four cylinders 19 are arranged, that is, the direction in which the crankshaft extends substantially coincides with the vehicle width direction of the vehicle (not shown). is there. That is, the lower side in FIG. 1 corresponds to the front side of the vehicle, the upper side corresponds to the rear side of the vehicle, the left side corresponds to the right side of the vehicle, and the right side corresponds to the left side of the vehicle. In FIG. 1 and FIGS. 7 to 9 described later, only the engine body 1 is viewed from the front of the vehicle for convenience of explanation. Further, in this specification, the longitudinal direction of the engine E, that is, the direction of the axis of the crankshaft is defined as the longitudinal direction of the engine E, and the output end side (right side in FIG. 1) of the crankshaft is referred to as the rear side of the engine E. On the other hand, the opposite side (the left side in FIG. 1) is called the front side of the engine E, and the right side is called the right side of the engine E when viewed from the rear side of the engine E, and the opposite side is called the left side of the engine E. Shall be called.

  A water jacket w is formed inside the engine body 1 so as to surround each cylinder 19, a cooling water outlet 24 of the water jacket w is formed on the rear side of the cylinder head 2, and a cylinder block 3 is formed with a bypass inlet 31 of the water jacket w. A water outlet member 6 for discharging cooling water is attached to a portion corresponding to the cooling water outlet 24 of the cylinder head 2. A water pump 41 is disposed on the front side surface of the cylinder block 3. Further, a thermostat housing 43 is disposed on the left side surface of the cylinder block 3. Furthermore, a temperature control valve 7 is disposed on the right side surface of the cylinder block 3. The temperature control valve 7 is attached to a mounting seat 32 (see FIG. 2) formed at a position corresponding to the right side of the foremost cylinder 19 on the right side surface of the cylinder block 3.

  The flow of cooling water in the engine E will be described with reference to FIG. 1. Cooling water supplied from the water pump 41 is introduced into the water jacket w from the front end of the cylinder block 3, and the following five flow paths are used. Return to the water pump 41 again. As a flow path for the cooling water to return to the water pump 41, after flowing through the water jacket w, a radiator path 81 that passes through the radiator 51 and a cabin that passes through the water jacket w and then passes through the cabin heater 52. After flowing through the heater passage 82 and the water jacket w, the ISC passage 83 passing through the throttle body 35, the engine oil warmer / cooler 37, and the electric heater 39, and the water jacket w, and then bypassing the radiator 51 A radiator bypass passage 84 and a water jacket bypass passage 85 that shortcuts the water jacket w are provided.

  The radiator passage 81 includes a radiator hose 81a that connects the water outlet member 6 and the radiator 51, a radiator 51, and a radiator return hose 81b that connects the radiator and the thermostat housing 43. The water outlet member 6 and the thermostat housing 43, the coolant outlet 24 of the water jacket w and the water pump 41 are connected. A passage returning from the water pump 41 through the water jacket w and the radiator passage 81 to the water pump 41 again constitutes a cooling water circulation passage.

  The cabin heater passage 82 includes a cabin heater hose 82 a that connects the water outlet member 6 and the cabin heater 52, a cabin heater return hose that connects the cabin heater 52, the cabin heater 52, and the temperature control valve 7. 82b, a cabin heater return passage downstream portion 82c formed in the cylinder block 3 and connecting the temperature control valve 7 and the water pump 41 (in FIGS. 1 and 7 to 9, for the sake of convenience of explanation, the outside of the cylinder block 3). The cooling water outlet 24 of the water jacket w and the water pump 41 are connected via the water outlet member 6 and the temperature control valve 7. The cabin heater return hose 82b constitutes an upstream portion of the cabin heater return passage, and the cabin heater return hose 82b and the cabin heater return passage downstream portion 82c constitute a cabin heater return passage.

  The ISC passage 83 includes a first ISC hose 83a that connects the water outlet member 6 and the throttle body 35, and a second ISC hose 83b that connects the throttle body 35, the throttle body 35, and the engine oil warmer / cooler 37. The engine oil warmer / cooler 37, the third ISC hose 83 c connecting the engine oil warmer / cooler 37 and the electric heater 39, the electric heater 39, the electric heater 39 and the thermostat housing 43. The cooling water outlet 24 of the water jacket w and the water pump 41 are connected via the water outlet member 6 and the thermostat housing 43. This ISC passage 83 constitutes an intake system cooling water passage. In addition, each ISC hose 83a, 83b, 83c constituting the ISC passage 83 has a small diameter compared to the radiator hose 81a constituting the radiator passage 81, the cabin heater hose 82a constituting the cabin heater passage 82, and the like. The flow rate of the cooling water flowing to the ISC passage 83 is small.

  The radiator bypass passage 84 is formed in the cylinder block 3 and connects the cooling water outlet 24 and the thermostat housing 43.

  The water jacket bypass passage 85 is formed in the cylinder block 3 and connects the bypass inlet 31 of the water jacket w and the cabin heater return passage downstream portion 82c. The water jacket bypass passage 85 and the cabin heater return are connected to each other. A temperature control valve 7 is provided at the junction with the passage downstream portion 82c.

  As shown in FIG. 2, the cylinder block 3 has a so-called ladder frame structure that is vertically divided by a horizontal plane passing through the crankshaft X. In the cylinder block 3, a water jacket w is formed so as to cover the cylinders 19, 19,. More specifically, the water jacket w extends in the cylinder row direction from the frontmost cylinder 19 to the rearmost cylinder 19 while being bent substantially along the cylinder wall on the left side of the engine of the four cylinders 19, 19. After that, it curves to the right side of the engine substantially along the rear cylinder wall of the rearmost cylinder 19 and further bends along the cylinder wall on the right side of the engine of the four cylinders 19, 19,. After extending from the cylinder 19 to the foremost cylinder 19 in the cylinder row direction, it curves to the left side of the engine substantially along the front cylinder wall of the frontmost cylinder 19 and communicates with the water jacket on the left side of the engine. . That is, the water jacket w is formed so that four cylinders 19, 19,... Are formed as a lump so as to cover the outer periphery in an annular shape, and this cylinder block 3 is disposed between adjacent cylinders 19, 19 (between the bores). Is a so-called siamese type with no water jacket formed. Further, the depth of the water jacket w is from the upper surface of the cylinder block 3 to a substantially central position in the height direction of the cylinder block 3 (corresponding to the position of the bottom dead center) (see FIG. 4). Although not shown, the water jacket w communicates with the water pump 41 at the front end portion thereof, and cooling water is supplied from the front end portion into the water jacket w by the water pump 41.

  A cylinder head 2 is attached to the upper part of the cylinder block 3. In the cylinder head 2, the cylinders 19, 19,... Are closed from above by the combustion chamber ceiling, and a water jacket w is formed so as to cover the upper portion of the combustion chamber ceiling. Further, a cooling water outlet portion 24 for discharging cooling water from the water jacket w is formed at the rear end portion of the cylinder head 2, and the cooling water outlet portion 24 opens at the rear end surface of the cylinder head 2. . A water outlet member 6 for discharging the cooling water from the water jacket w to the outside is attached to a position corresponding to the opening of the cooling water outlet portion 24 of the rear side wall portion 2c of the cylinder head 2.

  The water pump 41 is attached to a water pump housing 41a formed so as to bulge outward in the engine width direction at the upper left side portion of the front side wall portion 3a of the cylinder block 3 shown in FIGS. It has been. The water pump 41 has a discharge port connected to a front end portion of the water jacket w formed in the cylinder block 3. On the other hand, as shown in FIG. 3, the suction port 41b of the water pump 41 is formed so as to be recessed in the rear side of the engine in the water pump housing 41a, and the rear end thereof opens to the thermostat housing 43. A cabin heater return passage downstream portion 82c described later is connected to the suction port 41b of the water pump 41. That is, the water pump 41 sucks the cooling water supplied from the thermostat housing 43 and the cabin heater return passage downstream portion 82 c and discharges it to the water jacket w formed in the cylinder block 3. Although not shown, the water pump 41 is drivingly connected to a crankshaft disposed on the front side of the engine E, and is driven by the crankshaft. That is, the water pump 41 is a mechanically driven water pump.

  Further, as shown in FIG. 3, the thermostat housing 43 is provided at an upper portion and a front portion of the left side wall portion 3b of the cylinder block 3. The thermostat housing 43 is provided in the left side wall portion 3b of the cylinder block 3 so as to be recessed inwardly in the engine width direction, and a storage portion 43a communicating with the suction port 41b of the water pump 41, and a mounting flange 43b (FIG. 1). The thermostat valve 43c (see FIG. 1) is provided, and the mounting flange 43b is attached to the opening of the storage portion 43a so that the thermostat valve 43c is built in the storage portion 43a. The thermostat housing 43 includes a bypass inflow port 43d that opens from the left side wall 3b to the bottom of the storage portion 43a, and two ports, an ISC inflow port 43e and a radiator inflow port 43f that protrude outward from the mounting flange 43b. And a total of three inflow ports.

  The thermostat valve 43c is, for example, a wax type, and when the cooling water temperature is lower than a predetermined first temperature (95 ° C. in the present embodiment), the wax contracts and the urging force of the spring causes the valve body to be the shaft of the spring. It moves in the direction and closes the radiator inflow port 43f (state shown in FIG. 1). On the other hand, when the cooling water temperature becomes equal to or higher than the predetermined first temperature, the valve element moves in the axial direction of the spring due to the expansion of the wax, thereby opening the radiator inflow port 43f (see FIG. 9). Thus, the thermostat valve 43c opens and closes the radiator inflow port 43f in accordance with the coolant temperature. The thermostat valve 43c is integrally provided with a pressure relief valve 43g. The pressure relief valve 43g is disposed in the bypass inflow port 43d, and opens the bypass inflow port 43d when the coolant pressure becomes equal to or higher than a predetermined water pressure. On the other hand, when the coolant pressure is lower than the predetermined water pressure, The port 43d is closed. Thus, the pressure relief valve 43g opens and closes the bypass inflow port 43d according to the coolant pressure. Note that the ISC inflow port 43e has no on-off valve and is always in communication with the water pump 41.

  The radiator bypass passage 84 is formed in the left side wall 3b of the cylinder block 3 as shown in a part of FIG. Specifically, the upstream end thereof opens to the cooling water outlet portion 24 of the cylinder head 2, and the intermediate portion thereof is substantially the vertical direction of the cylinder block 3 from the cooling water outlet portion 24 in the left side wall portion 3 b of the cylinder block 3. After extending vertically downward to the center position, it extends in the cylinder row direction from the rear end portion of the cylinder block 3 toward the front end portion, and its downstream end opens to the bottom portion of the housing portion 43a of the thermostat housing 43, and flows into the bypass. A port 43d is formed.

  Further, as shown in FIGS. 3 and 4, the cabin heater return passage downstream portion 82c is formed at a substantially intermediate position in the vertical direction in the front side wall portion 3a of the cylinder block 3 (only a part is shown in FIG. 4). ). The cabin heater return passage downstream portion 82c has a downstream end communicating with the suction port 41b of the water pump 41, and an upstream end opened to a lower portion of the mounting seat 32 of the temperature control valve 7 to return the opening 32a. Is formed. Specifically, the cabin heater return passage downstream portion 82c extends from the right side surface of the front side wall portion 3a of the cylinder block 3 in the engine width direction and penetrates to the suction port 41b of the water pump 41, and from the mounting seat 32. A perforation 82e provided inward in the engine width direction, and extends obliquely from the front side surface of the front side wall portion 3a of the cylinder block 3 toward the rear side and the right side of the engine and penetrates the perforation 82d into the perforation 82e. It consists of a hole 82f that opens. Note that the opening on the right side of the front side wall 3a of the perforation 82d and the opening on the front side of the front side wall 3a of the perforation 82f are closed by plugs. Thus, the cabin heater return passage downstream portion 82c for guiding the cooling water from the return opening 32a of the mounting seat 32 to the water pump 41 through the perforation 82e, the perforation 82f, and the perforation 82d is formed.

  Further, as shown in FIGS. 4 and 5, the water jacket bypass passage 85 is formed in the front portion of the right side wall portion 3 c of the cylinder block 3. The water jacket bypass passage 85 has an upstream end connected to a bypass inlet portion 31 formed at a right side position of the cylinder 19 at the foremost portion of the water jacket w, and extends outward in the engine width direction. The end opens to the upper part of the mounting seat 32 of the temperature control valve 7 so as to form a bypass opening 32b.

  As described above, at the front portion of the cylinder block 3, the cabin heater return passage downstream portion 82c is formed at a substantially intermediate position in the vertical direction, and the water jacket bypass passage 85 is formed above the passage 82c.

  As shown in FIG. 2, the temperature control valve 7 is connected to a cabin heater return hose 82b, attached to the mounting seat 32, and communicated with the return opening 32a and the bypass opening 32b. A guide member 72 provided in the housing 71, and a cabin heater return passage communication state which is slidable in the guide member 72 and which communicates the cabin heater return hose 82b and the return opening 32a. A passage switching valve body 73 capable of switching between a water jacket bypass passage communication state for communicating the bypass opening 32b and the return opening 32a, and a biasing spring 74 for biasing the passage switching valve body 73 downward ( (Not shown in FIG. 2, only shown in FIG. 6) Temperature sensitive actuation section 75 from the (not shown in FIG. 2, only shown in FIG. 6). The housing 71 and the guide member 72 constitute a temperature control valve housing.

  As shown in FIGS. 2 and 4, the housing 71 has a cylindrical shape extending in the vertical direction and is opened upward, and is attached to the upper portion of the main body 71a by bolts 71c and 71c. The lid 71b closes the opening of the portion 71a from above. Further, the housing 71 has a mounting surface 71d (see FIG. 4) that contacts the mounting seat 32 when the housing 71 is mounted on the mounting seat 32 of the cylinder block 3 on the inner side of the engine. A cabin heater return hose 82 b is connected to the side, and a hose connection portion 71 e that opens into the housing 71 is formed. The mounting surface 71d communicates with a housing-side return opening 71f that communicates with a return opening 32a formed at the lower portion of the mounting seat 32, and a bypass opening 32b that is formed at the upper portion of the mounting seat 32. A housing side bypass opening 71g is formed. As described above, the housing 71 is formed with the housing-side bypass opening 71g above the hose connection 71e and the housing-side bypass opening 71g below the hose connection 71e.

  2 and 4, the guide member 72 has a cylindrical shape that is accommodated in the housing 71. From the top, the upper small diameter portion 72a, the upper large diameter portion 72b, the central small diameter portion 72c, A side large-diameter portion 72d, a lower small-diameter portion 72e, and a temperature-sensitive operating portion installation portion 72f are formed. The outer diameters of the upper large diameter portion 72b and the lower large diameter portion 72d coincide with the inner diameter of the main body portion 71a of the housing 71, and the outer diameters of the upper small diameter portion 72a, the central small diameter portion 72c, and the lower small diameter portion 72e are The inner diameter of the main body 71a of the housing 71 is smaller. The inner periphery of the guide member 72 is uniform from the upper small diameter portion 72 a to the lower large diameter portion 72 d and coincides with the outer periphery of the passage switching valve body 73. Further, the upper small diameter part 72a is formed with a plurality of communication holes 72h, 72h,... For communicating the inside and outside of the upper small diameter part 72a. The central small diameter part 72c communicates the inside and outside of the central small diameter part 72c. A plurality of communication holes 72i, 72i,... Are formed, and a plurality of communication holes 72j, 72j,... That communicate the inside and the outside of the lower small diameter portion 72e are omitted in the lower small diameter portion 72e. Is formed. When the guide member 72 is accommodated in the housing 71, the upper large-diameter portion 72b is positioned at a position between the housing-side bypass opening 71g and the opening of the hose connection portion 71e in the vertical direction. The lower large-diameter portion 72d is positioned at a position between the opening of the hose connection portion 71e and the housing-side return opening 71f, and is in contact with the inner peripheral surface of the main body 71a. . Further, in the vertical direction, the upper small diameter portion 72a is located at a position corresponding to the housing side bypass opening 71g, the central small diameter portion 72c is located at a position corresponding to the hose connection portion 71e, and a position corresponding to the housing side return opening 71f. The side small diameter portion 72e is positioned. That is, the housing-side bypass opening 71g, the hose connecting portion 71e, and the housing-side return opening 71f are respectively connected to communication holes 72h, 72h,..., A communication hole 72i formed in the central small-diameter portion 72c. , 72i,... And communication holes 72j, 72j,... Formed in the lower small diameter portion 72e communicate with the inside of the guide member 72.

  2 and 4, the passage switching valve body 73 has a cylindrical shape opened up and down, and the outer diameter of the passage switching valve body 73 is lower than the upper large diameter portion 72 a of the guide member 72 as described above. It corresponds to the inner diameter over the portion 72d. The total length of the passage switching valve body 73 corresponds to the length from the upper end of the upper large diameter portion 72b of the guide member 72 to the lower end of the lower large diameter portion 72d. Further, although not shown in FIGS. 2 and 4, the passage switching valve body 73 has a connecting portion 73 b (FIG. 6) that supports one end of the biasing spring 74 and is connected to the temperature-sensitive operating portion 75. Reference) is formed. The passage switching valve body 73 is formed with a plurality of communication holes 73a, 73a,... For communicating the inside and outside of the passage switching valve body 73 at a position away from the upper end by a predetermined distance in the vertical direction. The predetermined distance is such that the central small diameter of the guide member 72 is located when the passage switching valve body 73 is located at a position where the upper end portion closes the communication holes 72h, 72h, ... formed in the upper small diameter portion 72a of the guide member 72. It is set to a distance communicating with the downstream ends of the communication holes 72i, 72i,... Formed in the portion 72c. That is, when the upper end of the passage switching valve body 73 is located at a position lower than the communication holes 72h, 72h,... Of the upper small diameter portion 72a, the communication holes 72h, 72h,. The communication holes 72i, 72i,... Of the central small diameter portion 72c are closed by the wall surface of the passage switching valve body 73. On the other hand, when the communication holes 73a, 73a,... Of the passage switching valve body 73 are located at positions where they communicate with the communication holes 72i, 72i,... Of the central small diameter portion 72c, the communication holes 72i, 72i,. .. Are communicated with the inside of the passage switching valve body 73 through the communication holes 73a, 73a,..., And the communication holes 72h, 72h,. At this time, the lower opening of the passage switching valve body 73 is always attached via the communication holes 72j, 72j,... Formed in the lower small diameter portion 72e of the guide member 72 and the housing side return opening 71f of the housing 71. The seat 32 communicates with the return opening 32a.

  As shown in FIG. 6, the biasing spring 74 is disposed between the connecting portion 73b of the passage switching valve body 73 and the lid portion 71b of the housing 71, and biases the passage switching valve body 73 downward. is doing.

  The temperature-sensitive operation unit 75 includes a wax storage unit 75a in which wax as a temperature sensor is stored, and one end built in the wax storage unit 75a, and the other end connected to the passage switching valve body 73. And a rod member 75b connected to 73b. When the coolant temperature is lower than a predetermined second temperature (40 ° C. in this embodiment), the temperature-sensitive operation unit 75 moves the passage switching valve body 73 downward via the rod member 75b due to the wax contracting. On the other hand, when the cooling water temperature becomes equal to or higher than the predetermined second temperature, the wax expands to move the passage switching valve body 73 upward against the urging force of the urging spring 74 via the rod member 75b.

  The operation of the temperature control valve 7 configured as described above will be described with reference to a schematic diagram shown in FIG. In FIG. 6, the guide member 72 is represented integrally with the housing 71.

  When the cooling water temperature is lower than the predetermined second temperature, the upper end of the passage switching valve element 73 is connected to the communication member 72h of the guide member 72 by the urging spring 74 and the temperature sensitive operating part 75 as shown in FIG. Also, the passage switching valve body 73 is moved so as to be positioned below. At this time, the communication hole 72 i of the guide member 72 is closed by the wall surface of the passage switching valve body 73. Thus, the water jacket bypass passage 85 and the cabin heater return passage downstream portion 82c are communicated with each other, and the cabin heater passage 82 (the cabin heater return passage upstream portion) is closed.

  On the other hand, when the cooling water temperature is equal to or higher than the predetermined second temperature, the urging spring 74 and the temperature-sensitive operating portion 75 cause the communication hole 73a of the passage switching valve body 73 and the guide member 72 to be The passage switching valve element 73 is moved so that the communication hole 72i communicates. At this time, the communication hole 72 h of the guide member 72 is closed by the wall surface of the passage switching valve body 73. Thus, the water jacket bypass passage 85 is closed and the cabin heater return hose 82b and the cabin heater return passage downstream portion 82c are communicated, that is, the cabin heater passage 82 is opened.

  Although not shown, the throttle body 35 (see FIG. 1) is disposed in an intake pipe connected to an intake manifold provided in the cylinder head 2, and opens and closes a throttle valve in the intake pipe. To adjust the amount of intake air introduced from the intake pipe into the intake manifold. The throttle body 35 forms an intake passage together with an intake pipe, an intake manifold, and the like. The throttle body 35 forms a cooling water passage in the wall and circulates the cooling water, thereby preventing the throttle valve from being frozen with the intake pipe due to extremely low temperature intake air in a cold district or the like.

  The engine oil warmer / cooler 37 (see FIG. 1) exchanges heat between the cooling water and the engine oil. The cooling water warms the engine oil when it is cold, while the cooling water Plays a role in cooling engine oil. In other words, during the cold time, the temperature of the cooling water rises before the engine oil, so the amount of heat moves from the cooling water to the engine oil, and the engine oil is warmed. On the other hand, during the warm period, the temperature of the cooling water is maintained at a substantially constant temperature by the radiator. However, since the temperature of the engine oil continues to rise due to the amount of heat from the engine body 1, the amount of heat from the engine oil to the cooling water is reduced. It moves and the engine oil is cooled. The engine oil warmer / cooler 37 constitutes an oil / water heat exchanger. Although not shown, the engine oil warmer / cooler 37 is connected to an oil hose and an oil return hose, and a cooling water passage is formed inside the engine oil warmer / cooler 37. The cooling water is configured to circulate inside.

  The electric heater 39 has a role of heating the cooling water when it is cold, and directly heats the cooling water by an electric heater provided in the ISC passage 83. The electric heater 39 constitutes a cooling water heating device.

  The flow of the cooling water of the cooling device for the engine E configured as described above will be described according to the temperature course of the cooling water.

  When the cooling water temperature is lower than the predetermined second temperature (40 ° C.), the temperature control valve 7 closes the cabin heater passage 82 and opens the water jacket bypass passage 85 as shown in FIG. The thermostat valve 43 c closes the radiator passage 81. As a result, the cooling water supplied from the water pump 41 to the water jacket w flows through the water jacket bypass passage 85 bypassing the water jacket w, the water jacket w and the ISC passage 83, and returns to the water pump 41. Here, the passage returning from the water pump 41 to the water pump 41 through the water jacket bypass passage 85 again is the water jacket w and the ISC passage 83 (the cooling water passage in the throttle body 35 and the engine oil warmer / cooler 37). The flow resistance is smaller than that of the passage returning to the water pump 41 again through the water jacket 41, so that most of the cooling water discharged from the water pump 41 flows to the water jacket bypass passage 85. That is, most of the cooling water does not circulate through the water jacket w, so that the engine E is warmed up. However, since a small amount of cooling water always flows through the water jacket w and circulates to the ISC passage 83, the temperature of the locally high temperature portion (for example, the portion around the spark plug unit in the cylinder head 2) rises. In addition to being able to prevent overheating, the throttle valve in the throttle body 35 can be prevented from freezing, the engine oil can be warmed, and the cooling water can be warmed by the electric heater 39 at all times. Here, the engine oil warmer / cooler 37 and the electric heater 39 will be further described. The engine oil warmer / cooler 37 functions as a warmer because the cooling water temperature is higher than the engine oil temperature when the engine oil warmer / cooler 37 is cold. Heat the engine oil. Further, the electric heater 39 is turned on to heat the cooling water. The predetermined second temperature is set to 40 ° C. in the present embodiment, but is not limited to this, and the warming up of the engine E should be prioritized over the warming of the cabin by the cabin heater 52. Set to temperature.

  At this time, when the water pressure of the cooling water becomes equal to or higher than a predetermined water pressure, the pressure relief valve 43g of the thermostat housing 43 is opened as shown in FIG. 7, and the cooling water flows through the radiator bypass passage 84 to The water pressure drops.

  When the cooling water temperature is equal to or higher than the predetermined second temperature (40 ° C.) and lower than the predetermined first temperature (95 ° C.), the temperature control valve 7 opens the cabin heater passage 82 as shown in FIG. The jacket bypass passage 85 is closed, and the thermostat valve 43 c of the thermostat housing 43 closes the radiator passage 81. As a result, the cooling water supplied from the water pump 41 to the water jacket w flows through the water jacket w and flows through the cabin heater passage 82 and the water jacket w through the ISC passage 83 and returns to the water pump 41. That is, in this case, the engine E has been warmed up to some extent, and the cabin heater 52 has secured a sufficient amount of heat to warm the vehicle interior. At this time, the amount of heat received from the engine body 1 while the coolant flows through the water jacket w is first used to warm the vehicle interior by the cabin heater 52, and the rest is retained by the coolant without being radiated to the outside. The engine E is warmed up. At this time, the cooling water also flows through the ISC passage 83. As in the case where the cooling water temperature is lower than the predetermined second temperature, the engine oil warmer / cooler 37 functions as a warmer and the electric heater 39 is turned on. It has become. The predetermined first temperature is set to 95 ° C. in the present embodiment, but is not limited to this, and is not limited to the temperature at which the cooling water itself needs to be cooled, for example, the boiling point of the cooling water. It is better to set the temperature lower.

  When the cooling water temperature is equal to or higher than a predetermined first temperature (95 ° C.), the temperature control valve 7 opens the cabin heater passage 82 and closes the water jacket bypass passage 85 as shown in FIG. The thermostat valve 43 c opens the radiator passage 81. As a result, the cooling water supplied from the water pump 41 to the water jacket w flows through the cabin heater passage 82 and the radiator passage 81 from the water jacket w and returns to the water pump 41. That is, in such a case, the cooling water is heated too much and the cooling water itself needs to be cooled. At this time, the amount of heat received from the engine body 1 while circulating the cooling water jacket w is radiated by the radiator 51 and the cabin heater 52, so that the cooling water is cooled, and as a result, the engine E is cooled. At this time, the cooling water also flows through the ISC passage 83. At such a warm time, the cooling water temperature is converged to the vicinity of the predetermined first temperature by the radiator 51, but the temperature of the engine oil is higher than the first temperature. Therefore, the engine oil warmer / cooler 37 functions as a cooler to cool the engine oil. Moreover, since there is no need to heat the cooling water, the electric heater 39 is turned off.

  Therefore, when the cooling water temperature is lower than the predetermined second temperature at the junction of the cabin heater return hose 82b, the cabin heater return passage downstream portion 82c, and the water jacket bypass passage 85, the cooling device for the engine E has the water jacket bypass. While the passage 85 and the cabin heater return passage downstream portion 82c communicate with each other, the temperature control valve 7 communicates the cabin heater return hose 82b and the cabin heater return passage downstream portion 82c when the coolant temperature is equal to or higher than a predetermined second temperature. And a thermostat housing 43 is provided at the downstream end of the radiator passage 81 and the radiator bypass passage 84, and the radiator inflow port 43f is provided with a thermostat valve 43c whose cooling water temperature opens at a predetermined first temperature. 3d is provided with a pressure relief valve 43g that opens when the water pressure of the cooling water is equal to or higher than a predetermined water pressure, so that when the cooling water temperature is lower than the predetermined second temperature, that is, when the engine E needs to be warmed up early, By flowing the water through the water jacket bypass passage 85, not only the cooling water is prevented from flowing through the radiator passage 81 but also the cooling water is prevented from flowing through the cabin heater passage 82 and the radiator bypass passage 84. Thus, the engine E can be warmed up early. At this time, when the rotational speed of the engine increases, the cooling water discharge amount of the water pump 41 connected to the crankshaft also increases. When the cooling water temperature is lower than the predetermined second temperature, the flow passage communicating with the water pump 41 is only the ISC passage 83 and the water jacket bypass passage 85, so the water pressure of the cooling water may increase excessively. . However, in the cooling device for the engine E, when the water pressure of the cooling water becomes equal to or higher than a predetermined water pressure, the pressure relief valve 43g provided at the downstream end of the radiator bypass passage 84 is opened, and the cooling water is also supplied to the radiator bypass passage 84. It will flow, and the water pressure of cooling water will fall. As a result, it is possible to prevent the hoses constituting the cooling water passage including the radiator hose 81a from coming off as the cooling water pressure increases. Further, since the pressure relief valve 43g is provided in the radiator bypass passage 84, even if the cooling water pressure rises and the cooling water flows through the radiator bypass passage 84, the amount of heat of the cooling water is externally supplied. It does not radiate heat or is used to warm the passenger compartment, and the reduction in the amount of heat of the cooling water can be suppressed as much as possible.

  Further, the cooling device for the engine E has the passages 81 to 85 arranged as described above, and is provided with the temperature control valve 7, the thermostat valve 43c, and the pressure relief valve 43g, so that the flow passage of the cooling water according to the cooling water temperature. Therefore, early warm-up and cooling of the engine E can be realized without performing complicated control such as changing the flow rate of the cooling water discharged from the water pump 41 according to the cooling water temperature. This is particularly effective for a cooling device for engine E that employs a mechanically driven water pump that is difficult to control, such as water pump 41 driven by a crankshaft. Cost reduction can be achieved.

  Further, in the cooling device for the engine E, even when the radiator passage 81 and the cabin heater passage 82 are closed, the ISC passage 83 through which a small amount of cooling water is always circulated provides an early warm-up of the engine E. Even when it is cold, the throttle valve in the throttle body 35 can be frozen, the engine oil warmer / cooler 37 can heat and cool the engine oil, and the electric heater 39 can heat the coolant.

  Further, the temperature control valve is formed by forming the cabin heater return passage downstream portion 82c and the water jacket bypass passage 85 in the cylinder block 3 and forming the return opening portion 32a and the bypass opening portion 32b in the mounting seat 32. 7 arrangement and attachment workability can be improved. Further, since the water jacket w is formed from the upper end of the cylinder block 3 to a depth at a substantially central position in the vertical direction, the bypass opening 32b is formed at the upper portion and the return opening 32a is formed at the lower portion of the mounting seat 32. The water jacket bypass passage 85 and the cabin heater return passage downstream portion 82c can be easily arranged in the cylinder block 3. Further, since the temperature control valve 7 is operated by the temperature-sensitive operating unit 75 using wax that contracts and expands according to the cooling water temperature, the cabin heater passage 82 and the water jacket bypass passage 85 are selected according to the cooling water temperature. Uniform opening / closing control can be realized at low cost without using a solenoid valve or the like. Of the perforations 82d to 82f constituting the cabin heater return passage downstream portion 82c of the present embodiment, the perforations formed through the right side surface of the front side wall portion 3a of the cylinder block 3 to the suction port 41b of the water pump 41. When the water jacket bypass passage 85 is not provided, the downstream portion of the cabin heater return passage 82d can be configured by providing a connection portion of the cabin heater return hose 82b at the opening end of the right side surface thereof. That is, when the water jacket bypass passage 85 is provided in the engine E, the water jacket bypass passage 85 is formed and the perforations 82e and 82f are formed, so that the cabin heater return when the water jacket bypass passage 85 is not provided is formed. It is possible to easily form a new cabin heater return passage downstream portion 82c by remodeling while utilizing the passage downstream portion.

  Furthermore, since the radiator bypass passage 84 through which the cooling water flows is formed in the cylinder block 3 to reduce the water pressure when the cooling water pressure increases, the heat quantity of the cooling water is radiated to the outside. This can be suppressed as much as possible, and the engine E can be warmed up earlier. In addition, by forming the radiator bypass passage 84 in the left side wall portion 3b of the cylinder block 3, the complexity of piping the radiator bypass passage 84 to the outside with respect to the engine body 1 can be eliminated. The length can be shortened. Furthermore, since the thermostat valve 43c and the pressure relief valve 43g are integrally formed, and the radiator passage 81 and the radiator bypass passage 84 are connected to the thermostat housing 43, the passage of these passages is facilitated, and the thermostat valve Assembling workability of 43c and the pressure relief valve 43g can be improved.

<< Other Embodiments >>
The present invention may be configured as follows with respect to the above embodiment. That is, in the above embodiment, the engine oil warmer / cooler 37 is employed as the oil-water heat exchanger, but the present invention is not limited to this. For example, an ATF warmer cooler that exchanges heat between cooling water and automatic transmission oil (ATF) may be used, and both an engine oil warmer cooler 37 and an ATF warmer cooler may be employed. .

It is a piping diagram of the cooling device of the engine concerning the embodiment of the present invention. It is a perspective view of a cylinder block and a temperature control valve. It is sectional drawing in the AA of FIG. It is sectional drawing in the BB line of FIG. It is sectional drawing in the CC line of FIG. It is a schematic diagram which shows operation | movement of a temperature control valve, Comprising: (a) shows the case where cooling water temperature is less than predetermined 2nd temperature, (b) shows the case where cooling water temperature is more than predetermined 2nd temperature. It is a schematic diagram which shows the flow of a cooling water when a cooling water temperature is less than predetermined 2nd temperature and the water pressure of a cooling water is more than a predetermined water pressure. It is a schematic diagram which shows the flow of a cooling water when a cooling water temperature is more than predetermined 2nd temperature and less than predetermined 1st temperature. It is a schematic diagram which shows the flow of a cooling water when a cooling water temperature is more than predetermined 1st temperature.

Explanation of symbols

E Engine w Water jacket 2 Cylinder head 24 Cooling water outlet (cooling water outlet)
3 Cylinder block 32 Mounting seat 35 Throttle body (intake passage)
37 Engine oil warmer / cooler (oil-water heat exchanger)
39 Electric heater (cooling water heater)
41 Water Pump 41a Water Pump Housing 43c Thermostat Valve (Thermostat)
43g Pressure relief valve 51 Radiator 52 Cabin heater 7 Temperature control valve 71 Housing (temperature control valve housing)
72 Guide member (temperature control valve housing)
73 passage switching valve element 81 radiator passage 82 cabin heater passage 82b cabin heater return hose (cabin heater return passage, upstream portion of cabin heater return passage)
82c Downstream part of cabin heater return passage (cabin heater return passage)
83 ISC passage (intake system coolant passage)
84 Radiator bypass passage 85 Water jacket bypass passage

Claims (4)

A cooling water circulation passage including a water jacket formed in the cylinder block and the cylinder head and a radiator passage having a radiator interposed therebetween, and returning from the water pump to the water pump via the water jacket and the radiator passage. When,
A radiator bypass passage that is provided in the middle of the cooling water circulation passage and bypasses the radiator;
A cabin heater passage provided in parallel with the radiator passage, and a cabin heater unit interposed in the middle;
A thermostat valve that closes the radiator passage when a coolant temperature is lower than a predetermined first temperature;
The upstream end is connected to the upstream side of the water jacket, while the downstream end is joined and connected to the cabin heater return passage that forms the downstream side of the cabin heater unit in the cabin heater passage, and the water jacket serves as a shortcut. A jacket bypass passage,
Provided at a junction between the cabin heater return passage and the water jacket bypass passage, and closes the cabin heater passage when the coolant temperature is lower than a predetermined second temperature lower than the predetermined first temperature and A temperature control valve that opens the jacket bypass passage, and opens the cabin heater passage and closes the water jacket bypass passage when the coolant temperature is equal to or higher than the predetermined second temperature;
A cooling device for an engine, further comprising: a pressure relief valve provided in the radiator bypass passage and opening the radiator bypass passage when the coolant pressure becomes equal to or higher than a predetermined water pressure. The engine cooling device according to claim 1,
An intake system cooling water passage that is provided in parallel with the radiator passage and the cabin heater passage, and that circulates the cooling water through a wall of the intake passage for introducing intake air to the engine;
The intake system cooling water passage is provided with at least one of a cooling water heating device for raising the temperature of the cooling water when cold and an oil-water heat exchanger for exchanging heat between the cooling water and oil. The engine cooling device. The engine cooling device according to claim 1 or 2,
A water pump housing of the water pump is formed on one side of the cylinder block front part,
A mounting seat for the temperature control valve is formed on the other side wall of the front portion of the cylinder block.
The cabin heater return passage has a cabin heater return passage upstream portion upstream of the temperature control valve, and a cabin heater return passage downstream portion downstream of the temperature control valve,
The downstream portion of the cabin heater return passage is formed in the cylinder block so that, at the front portion of the cylinder block, the upstream end opens to the lower portion of the mounting seat, and the downstream end communicates with the water pump housing. ,
The water jacket bypass passage is formed in the cylinder block so that an upstream end is connected to an upstream side of the water jacket at a front portion of the cylinder block and a downstream end is opened to an upper portion of the mounting seat. And
The temperature control valve is
A temperature control valve housing that is attached to the mounting seat and communicates with the downstream portion of the cabin heater return passage, the water jacket bypass passage, and the upstream portion of the cabin heater return passage;
A state provided in the temperature control valve housing and slidable up and down, wherein the upstream portion of the cabin heater return passage communicates with the downstream portion of the cabin heater return passage; the water jacket bypass passage and the cabin heater; A passage switching valve body capable of switching between a state in which the downstream portion of the return passage is communicated, and
An engine cooling apparatus comprising a temperature sensing element that moves the passage switching valve body up and down in accordance with the temperature. The engine cooling device according to claim 3.
A thermostat housing that communicates with the water pump and incorporates the thermostat valve is formed on a side wall of the cylinder block front portion where the water pump housing is formed.
The downstream end of the radiator passage is pipe-connected to the thermostat housing,
The radiator bypass passage is formed in the side wall on the one side of the cylinder block, and is open to the cylinder block inner side of the thermostat housing.
The engine cooling device, wherein the thermostat valve is configured integrally with a pressure relief valve for opening and closing the opening of the radiator bypass passage.

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