JP4492240B2 - Engine cooling system - Google Patents

Description

  The present invention relates to an engine cooling apparatus.

  As is well known, in a vehicle equipped with an engine such as an automobile, the engine is cooled by circulating cooling water between the water jacket of the engine and the radiator by a water pump. In order to ensure, at the time of engine cold start, it is calculated | required that the circulation of a cooling water is suppressed. Ensuring warm-up performance at an early stage is very important for activating the catalyst early and achieving good exhaust performance when a catalyst device is provided in the exhaust path.

  Conventionally, as a technique for ensuring warm-up performance at an early stage, for example, Japanese Patent Application Laid-Open No. 11-117740 (Patent Document 1) discloses a flow rate of cooling water in a heater path communicating with a vehicle compartment heater at the time of engine cold start. What reduces is disclosed. Further, conventionally, in a cooling device having a configuration in which a bypass path is attached to the radiator, and cooling water is allowed to flow to the bypass path at a low temperature and to the radiator at a high temperature, various devices provided in the bypass path and in the middle of the bypass path In order to avoid heat dissipation from the engine, it is known to reduce the flow rate of the cooling water in the bypass path when the engine is cold started.

Japanese Patent Laid-Open No. 11-117740

By the way, in the above prior art, in order to control the flow rate of the cooling water in the heater path and the bypass path, the temperature sensing part for sensing the temperature of the cooling water flowing in the path, and the temperature sensed by the temperature sensing part. A thermostat provided with a valve body that opens and closes in accordance with the change is employed, and in either case, the thermostat is disposed so that the temperature sensing part and the valve body are both disposed in the same path. However, in such a configuration, in order for the temperature sensing unit to sense the temperature of the cooling water, it is necessary to constantly flow a small amount of cooling water in the path, which may hinder improvement in warm-up performance.
Conventionally, in order to control the circulation of cooling water in a route such as a heater route, an electromagnetic valve is installed in the route, and the electromagnetic valve is arbitrarily controlled to be opened and closed to prevent the circulation of the cooling water. However, in this case, since an expensive electromagnetic valve is employed, the cost is increased.

  The present invention has been made in view of the above technical problem, and can minimize the circulation of cooling water at the time of cold start, and can achieve early warm-up of the engine with a simpler configuration and at a lower cost. An object of the present invention is to provide a cooling device.

Accordingly , an invention according to claim 1 of the present application is directed to a cooling system for an engine that cools an engine body by circulating cooling water through a water jacket formed inside the engine by a mechanical water pump. A cooling water passage for the heater that communicates with the heater for indoor heating, a cooling water passage for the radiator that communicates with the radiator that radiates the cooling water, and a radiator bypass passage that bypasses the cooling water passage for the radiator A throttle valve unit cooling water path that communicates with an intake throttle valve unit that controls the amount of air sucked into the engine and through which cooling water constantly circulates during engine operation, and is connected to the throttle valve unit cooling water path A temperature sensing device that is arranged and senses the temperature of the cooling water flowing through the cooling water passage for the throttle valve unit. And a first thermostat that is disposed in the cooling water passage for the heater and that is opened and closed in accordance with a temperature change sensed by the temperature sensing unit. A second thermostat having a valve body that opens and closes to the path and the radiator bypass path is disposed, and in the first thermostat, the temperature sensing portion and the valve body are partitioned from each other to form a water jacket. Is disposed in a water outlet member provided on the cooling water outflow side, and a pressure relief valve that is opened at a predetermined water pressure or higher is disposed in the radiator bypass path. The heater cooling water passage is closed by the valve body of the first thermostat, and the radiator cooling water passage is closed by the valve body of the second thermostat, Eta bypass path is that characterized in that it is closed by the pressure relief valve.
Further, in the invention according to claim 2 of the present application, in the invention according to claim 1, a cooling water path for the exhaust gas recirculation apparatus connected to the exhaust gas recirculation apparatus is provided in parallel with the cooling water path for the heater, When the engine is cold started, the heater cooling water passage and the exhaust gas recirculation device cooling water passage are closed by the valve body while the temperature of the cooling water below a predetermined value is sensed by the temperature sensing portion of the first thermostat. It is characterized by that.

According to the invention of claim 1 of the present gun, at the time of starting cold engine, and can flow only the cooling water for the throttle valve unit, the flow of cooling water is minimized, improving the warm-up characteristics it can.
Further, according to the invention according to claim 2 of the present application, the circulation of the cooling water to the exhaust gas recirculation device is also prevented, thereby further reducing the circulation of the cooling water at the time of engine cold start. Can be realized more reliably.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1. FIG.
1 and 2 are a perspective view schematically showing an engine according to Embodiment 1 of the present invention, and an explanatory view showing piping of a cooling device for the engine, respectively. In FIG. 1, the left front side of the drawing corresponds to the front side of the engine 1, and the right back side of the drawing corresponds to the rear side of the engine. The engine 1 has an engine main body portion 4 including a cylinder block 2 and a cylinder head 3 disposed on the upper side of the cylinder block 2, and includes four cylinders along the longitudinal direction of the engine main body portion 4. Is an in-line four-cylinder engine. In the engine room (not shown), the engine 1 is such that the longitudinal direction of the main body 4 thereof is parallel to the longitudinal direction of the vehicle body, and a crankshaft (not shown) incorporated in the engine 1 extends along the vehicle width direction. It is arranged horizontally so as to extend. A transmission 10 (shown in phantom lines) is disposed on the rear side of the engine 1.

  A cylinder cover 5 is disposed above the cylinder head 3. Furthermore, an intake manifold 6 for introducing intake air into each cylinder is disposed on the side of the engine body 4 (the right front side in FIG. 1). The intake manifold 6 includes four branch pipes, and each branch pipe communicates with each cylinder configured in the engine body 4. On the other hand, an exhaust system (exhaust manifold 19 or the like) is disposed on the side of the engine body 4 opposite to the side on which the intake manifold 6 is disposed (the left rear side in FIG. 1). .

  A water jacket (not shown) is formed inside the engine main body 4 composed of the cylinder block 2 and the cylinder head 3, and a discharge port of a water pump 7 for circulating cooling water is provided at the inlet of the water jacket. Is connected. The water pump 7 is a spiral centrifugal pump, is disposed on the front side of the cylinder block 2, and is connected to a crank pulley 8 provided on the front side of the cylinder block 2 by a V-belt (not shown). Drive coupled. Thereby, the water pump 7 is driven by the crankshaft (not shown). The water pump 7 is connected to a heater return pipe 9 that constitutes a heater return path between the air heating heater 30 (see FIG. 2) and the water pump 7.

  Further, a thermostat valve unit 11 that is disposed between the intake manifold 6 and the water pump 7 and communicates with the suction port of the water pump 7 is provided on the side of the cylinder block 2. The thermostat valve unit 11 has a radiator bypass inflow port 12 opened on the upper surface side thereof, and has a throttle valve unit inflow port 13 and a radiator inflow port 14 protruding to the side. A radiator bypass pipe 15 constituting a radiator bypass path is connected to the radiator bypass inflow port 12. The throttle valve unit inflow port 13 forms a throttle valve unit return path between the intake throttle valve unit 32 (see FIG. 2) and the water pump 7 for controlling the amount of air supplied to the engine. A throttle valve unit return pipe 16 is connected. Further, a radiator return pipe 17 constituting a radiator return path is connected to the radiator inflow port 14 between the radiator 34 (see FIG. 2) and the water pump 7.

  Although not specifically shown, a thermostat is disposed inside the thermostat valve unit 11. This thermostat has a wax element as a temperature sensing part that senses the temperature of cooling water flowing in a specific path, and a valve body that opens and closes according to the deformation of the wax element. The valve body is arranged so as to block the radiator bypass inflow port 12 and the radiator inflow port 13 in accordance with the detected temperature change of the cooling water. More specifically, when the coolant temperature sensed by the wax element is low, such as when the engine is cold started, the wax element contracts and the valve element closes the radiator inflow port 13 and opens the radiator bypass inflow port 12. On the other hand, when the cooling water temperature becomes a predetermined temperature or more, the wax element expands, and the valve element opens the radiator inflow port 13 and closes the radiator bypass inflow port 12. In this manner, the thermostat valve opens the radiator bypass inflow port 12 or the radiator inflow port 13 according to the coolant temperature, and communicates each with the water pump 8. The throttle valve unit inflow port 13 does not act on the valve body, and the throttle valve unit inflow port 13 is always in communication with the water pump 8 so that the cooling water flows.

  A water outlet member 20 communicates with the water jacket on the cooling water outflow side of the water jacket formed inside the engine body 4 at the rear side of the engine body 4 (strictly, the cylinder head 3). Is attached. FIG. 3 is an enlarged perspective view showing the water outlet member 20 and various paths connected thereto. The water outlet member 20 has four outlet ports (heater outlet port 21, radiator outlet port 22, radiator bypass outlet port 23, throttle valve unit outlet port 24). A heater pipe 25 that constitutes a heater path is connected to the heater outflow port 21 between the room heating heater 30 and the water outlet member 20. The radiator outlet port 22 is connected to a radiator pipe 26 that constitutes a radiator path between the radiator 34 and the water outlet member 20, and the radiator bypass outlet port 23 is connected to a radiator bypass path 15. Yes. Furthermore, a throttle valve unit pipe 27 that constitutes a throttle valve unit path is connected to the throttle valve unit outflow port 24 between the throttle valve unit 32 and the water outlet member 20.

  The engine 1 also includes an exhaust gas recirculation device (not shown) for returning a part of the exhaust gas to the intake system (intake manifold 6 or the like) and lowering the maximum temperature when the air-fuel mixture burns to suppress the generation amount of NOx. Hereinafter, an EGR (exhaust gas recirculation device) is mounted, and FIG. 2 shows a water-cooled EGR valve 36 provided as a main component of the device. The water-cooled EGR valve 36 controls the supply amount of cooling water into an EGR cooler (not shown) for cooling the exhaust gas returned to the intake system. The cooled exhaust gas is returned to the intake system via the pipes 37a and 37b and the water-cooled EGR 36 valve. The water-cooled EGR valve 36 and the EGR cooler are arranged in parallel with the heater 30 between the heater path and the heater return path. That is, a part of the cooling water flowing out from the water outlet member 20 through the heater path is supplied to the water-cooled EGR valve 36 and the EGR cooler and used. The cooling water after being used in the water-cooled EGR valve 36 and the EGR cooler is sent to the water pump 7 via the heater return path 9.

  Further, as shown in FIG. 2, as a cooling device for the engine 1, a pressure relief valve 40 is disposed in a radiator pipe 15 that constitutes a radiator bypass path. The pressure relief valve 40 closes the radiator bypass path when the water pressure of the cooling water flowing through the radiator bypass path is less than a predetermined value, and opens the radiator bypass path when the water pressure of the cooling water exceeds a predetermined value.

  Next, the water outlet member 20 will be described in detail. FIG. 4 schematically shows the internal structure of the water outlet member. As can be seen from this figure, the water outlet member 20 is attached to an outlet 3a of a water jacket formed in the cylinder head 3, and includes a heater pipe 25 that constitutes a heater path, a radiator pipe 26 that constitutes a radiator path, A heater outlet port 21, a radiator outlet port 22, a radiator bypass outlet port 23, which connect the throttle valve unit pipe 27 constituting the throttle valve unit path and the radiator bypass pipe 15 constituting the radiator bypass path so as to allow the flow of cooling water, respectively; A throttle valve unit outlet port 24 is provided.

  In addition, a thermostat 50 is disposed inside the water outlet member 20. Similar to the thermostat disposed in the thermostat valve unit 11, the thermostat 50 includes a wax element 51 as a temperature sensing unit that senses the temperature of the cooling water flowing in a specific path, and the deformation of the wax element 51. And a valve body 52 (first valve body 52a and second valve body 52b) that is driven to open and close. Within the water outlet member 20, the thermostat 50 has a wax element 51 disposed in a throttle valve unit outflow port 24 communicating with the throttle valve unit 32 via a throttle valve unit path, while a valve body 52 is provided with a heater. It arrange | positions so that it may arrange | position in the heater outflow port 21 which leads to a path | route. The throttle valve unit outlet port 24 is supplied with cooling water for preventing icing of the throttle valve supplied to the throttle valve unit 32 and cooling water for detecting an idle speed control (ISC) water temperature of the engine 1. It can be circulated at all times during operation. The wax element 51 senses the temperature of the cooling water in the outflow port 24 of the throttle valve unit, and the first valve body 52a and the second valve body 52b each sense a predetermined cooling water temperature by the wax element 51. In this case, the heater outflow port 21 is closed.

When the cooling water temperature in the throttle valve unit outflow port 24 sensed by the wax element 51 is low, the wax element 51 contracts, the valve body 52 moves in the axial direction of the spring 53, and the first valve body 52a The heater outflow port 21 is closed by seating on the first valve seat portion 21 a formed in the heater outflow port 21. Thereby, circulation of the cooling water to the heater path is prevented. At this time, the second valve body 52b is not seated on the second valve seat portion 21b formed in the heater outflow port 21 like the first valve seat portion 21a.
When the cooling water temperature in the throttle valve unit outflow port 24 rises, the wax element 51 expands, and the first valve body 52a moves away from the first valve seat portion 21a. Both 52a and the second valve body 52b are not seated, and cooling water can be circulated to the heater path.
Further, when the cooling water temperature in the throttle valve unit outflow port 24 becomes a predetermined temperature or more, the wax element 51 expands and the second valve body 52b is seated on the second valve seat portion 21b. 21 is closed. Thereby, circulation of the cooling water to the heater path is prevented. At this time, the first valve body 52a is not seated on the first valve seat portion 21a.

  In the cooling device for the engine 1, when the engine is cold-started, first, in the water outlet member 15, the first valve body 52 a of the thermostat 50 is seated on the first valve seat portion 21 a, thereby entering the heater path. The cooling water flow is blocked. Since the heater outflow port 21 is closed, in this state, the circulation of the cooling water to the water-cooled EGR valve 36 and the EGR cooler is similarly prevented. Second, in the thermostat valve unit 11, the coolant temperature sensed by the wax element of the second thermostat (not shown) is low, the valve body closes the radiator inflow port 13, and the pressure relief valve 40 is The radiator bypass path is closed until the cooling water pressure reaches a predetermined level or higher. As a result, the circulation of the cooling water to the radiator path and the radiator bypass path communicating with the radiator inflow port 13 is prevented.

  That is, in the cooling device for the engine 1, when the engine is cold-started, the water outlet member 20 is prevented from flowing the cooling water in the heater path, the water-cooled EGR valve 36, the EGR cooler, the radiator path, and the radiator bypass path. Circulation of cooling water is permitted only for the cooling system for the throttle valve unit such as the unit path and the throttle valve unit return path, and the circulation of the cooling water in the entire cooling device can be minimized. As described above, in the cooling device using the mechanical water pump 7, by providing the water outlet member 20 and the pressure relief valve 40, it is possible to start the engine cold with a relatively simple configuration and without causing an increase in cost. The circulation of the cooling water at the time can be suppressed to a minimum, and good early warm-up property and early activation of the catalyst can be realized. Further, in the water outlet member 20, since the wax element 51 and the valve body 52 of the thermo slot 50 are disposed in different cooling water paths, the wax element 51 always achieves a stable temperature sensitivity and prevents hunting. can do. Further, as the path on which the wax element 51 is arranged, a throttle valve unit path can be used, and the configuration can be simplified.

  Further, as can be seen from FIGS. 1 and 3, in the cooling device for the engine 1, the water pump 7 is attached to the front side of the engine 1, while the water outlet member 20 is attached to the engine 1 on the rear side of the engine 1. It is attached to the upper side of the transmission 10 arranged in series. A heater pipe 25, a radiator pipe 26, a radiator bypass pipe 15, and a throttle valve unit pipe 27 are connected to the water outlet member 20. Although not particularly shown, an EGR coolant path that branches from the heater pipe 25 is disposed on the upper side of the transmission 10. In this way, since various pipes connected to the weight outlet member 20 are concentrated in the empty space on the upper side of the transmission 10 disposed on the lower side at the rear side portion of the engine 1, the piping is simplified. Is possible.

  In the first embodiment, the wax element 51 of the thermostat 50 disposed in the water outlet member 20 is disposed in the throttle valve unit outflow port 24. However, the present invention is not limited thereto, and the engine 1 is in operation. Even if it is arranged at least in the path or port through which the cooling water flows at the time of starting, the same operation and effect as the effect brought about by the first embodiment can be realized.

Reference Example FIG. 5 is a diagram showing piping of an engine cooling device according to a reference example of the present invention. In the following, the same components as those in the first embodiment are denoted by the same reference numerals, and further description thereof is omitted. In this reference example , the heater return pipe 9 constituting the heater return path is connected to the throttle valve return pipe 16 constituting the throttle valve unit return path on the downstream side. Further, the radiator bypass pipe 15 constituting the radiator bypass path is connected to the thermostat valve unit 60 on the downstream side in the same manner as in the first embodiment, and on the upstream side, the radiator pipe 26 constituting the radiator path is arranged. It is connected to the middle part.

  FIG. 5 further shows an EGR cooler 38 in addition to the water-cooled EGR valve 36 as a main configuration of the EGR device. Further, a catalyzer 39 that is directly connected to the exhaust manifold 19 and supplies a part of the exhaust to the EGR cooler 38 is shown. When the cooling water is sent out from the water outlet member 20 to the heater pipe 25 constituting the heater path, a part of the cooling water is sent to the water-cooled EGR valve 36 and further supplied to the EGR cooler 38 through the pipe 36a. . The cooling water after being used in the EGR cooler 38 is sent to the thermostat valve unit 60 through the pipe 38a, the heater return pipe 9, and the throttle valve unit return pipe 16. A part of the exhaust gas is supplied from the catalyzer 39 to the EGR cooler 38 via the pipe 39a, and the cooled exhaust gas is taken into the intake air via the pipes 37a and 37b and the water-cooled EGR valve 36 as in the first embodiment. Returned to the system.

FIG. 6 schematically shows the internal structure of the thermostat valve unit 60. In this reference example , a thermostat valve unit 60 is connected to a throttle valve unit inflow port 81 to which a throttle valve unit return pipe 16 that constitutes a throttle valve unit return path is connected, and to a radiator return pipe 17 that constitutes a radiator return path. A radiator inflow port 82, a radiator bypass inflow port 83 to which a radiator bypass pipe 15 constituting a radiator bypass path is connected, and a water pump connection connected to the water pump 7 directly or via a coupling pipe (not shown). A port (hereinafter referred to as a W / P connection port) 84. Here, the throttle valve unit inflow port 81 communicates with the W / P connection port 84 via sleeves (not shown) connected to the ports 85 and 86 at both ends. Further, the radiator inflow port 82, the radiator bypass inflow port 83, and the W / P connection port 84 communicate with each other inside the thermostat valve unit 60.

  A thermostat 70 is disposed inside the thermostat valve unit 60. The thermostat 70 includes a wax element 71 serving as a temperature sensing unit that senses the temperature of cooling water flowing in a specific path, and a valve body 72 (first valve body 72a and the first valve body 72a) that is opened and closed according to deformation of the wax element 71. Second valve body 72b). Within the thermostat valve unit 60, the thermostat 70 is disposed such that the wax element 71 is disposed in the throttle valve unit return path and the valve body 72 is disposed in the W / P connection port 84. ing. Cooling water that has passed through the throttle valve unit is circulated through the throttle valve unit inflow port 81 constantly during operation of the engine 1. The wax element 71 senses the temperature of the cooling water flowing in the return path of the throttle valve unit, and the first valve body 72a and the second valve body 72b sense the predetermined cooling water temperature by the wax element 71, respectively. In this case, the first valve seat 82a formed between the radiator inflow port 82 and the W / P connection port 84 and the radiator bypass inflow port 83 and the W / P connection port 84 are formed. The second valve seat portion 83a is seated.

  When the coolant temperature in the return path of the throttle valve unit sensed by the wax element 71 is low, the wax element 71 contracts, the valve body 72 moves in the axial direction of the spring 73, and the first valve body 72a becomes the first valve body 72a. The radiator inflow port 82 and the W / P connection port 84 are blocked by being seated on the one valve seat portion 82a. Thereby, the circulation of the cooling water from the radiator inflow port 82 to the W / P connection port 84 is prevented. In this case, the second valve body 72b is not seated on the second valve seat portion 83a.

  On the other hand, when the coolant temperature in the return path of the throttle valve unit sensed by the wax element 71 exceeds a predetermined value, the wax element 71 expands and the valve element 72 moves in the axial direction of the spring 73, and the second valve When the body 72b is seated on the second valve seat portion 83a, the radiator bypass inflow port 83 and the W / P connection port 84 are blocked. Thereby, the flow of the cooling water from the radiator bypass inflow port 83 to the W / P connection port 84 is prevented. In this case, the first valve body 72a is not seated on the first valve seat portion 82a.

In this reference example , the same effect as in the first embodiment described above is ensured. Further, in addition to the thermostat 50 in the water outlet member 20, the wax element 71 and the valve body 72 are also provided for the thermostat 70 in the thermostat valve unit 60. Are arranged in cooling water paths different from each other, the wax element 71 can always achieve a stable temperature sensitivity and prevent hunting. Further, since the throttle valve unit path is used as the path on which the wax element 71 is disposed, the configuration can be simplified.

  It should be noted that the present invention is not limited to the illustrated embodiments, and it goes without saying that various improvements and design changes can be made without departing from the scope of the present invention. In the above-described embodiment, the thermostat is provided inside the water outlet member. However, the thermostat is not limited to this, and the thermostat is connected to the cooling water outflow side of the water jacket and the wax element and the valve body, which are the temperature sensing parts, to each other. As long as it can arrange | position in a different path | route, you may arrange | position not only inside a water outlet member but in any location.

  The engine cooling device according to the present invention can be applied to any type of vehicle as long as it includes a vehicle such as an automobile and is equipped with an engine.

1 is a perspective view schematically showing an engine according to Embodiment 1 of the present invention. It is a figure showing piping of the cooling device of the engine concerning the above-mentioned Embodiment 1. It is a perspective view which expands and shows a water outlet member and the various path | routes connected to it. It is explanatory drawing which shows schematically the internal structure of the said water outlet member. It is a figure showing piping of a cooling device of an engine concerning a reference example of the present invention. It is a figure which shows schematically the internal structure of the thermostat valve unit contained in the cooling device of the engine which concerns on the said reference example .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Cylinder block 3 ... Cylinder head 4 ... Engine main-body part 5 ... Cylinder cover 7 ... Water pump 9 ... Heater return pipe 10 ... Transmission 11,60 ... Thermostat valve unit 15 ... Radiator bypass pipe 16 ... Throttle valve unit Return pipe 17 ... Radiator return pipe 20 ... Water outlet member 25 ... Heater pipe 26 ... Radiator pipe 27 ... Throttle valve unit pipe 30 ... Heater 32 ... Intake throttle valve unit 34 ... Radiator 36 ... Water-cooled EGR valve 38 ... EGR cooler 40 ... Pressure Relief valve 50, 70 ... Thermostat 51, 71 ... Wax element 52, 72 ... Valve body

Claims (2)

In a cooling device for an engine that cools an engine body by circulating cooling water through a water jacket formed in an engine and circulating it with a mechanical water pump .
On the cooling water outflow side of the water jacket, a heater cooling water path communicating with the indoor heating heater, a radiator cooling water path communicating with the radiator that radiates the cooling water, and a radiator bypassing the radiator cooling water path A bypass path is connected to an intake throttle valve unit that controls the amount of air sucked into the engine, and is connected to a throttle valve unit cooling water path through which cooling water constantly flows during engine operation.
A temperature sensing part that is disposed in the cooling water path for the throttle valve unit and senses the temperature of the cooling water flowing in the cooling water path for the throttle valve unit; and is disposed in the cooling water path for the heater. A first thermostat having a valve body that opens and closes in response to a temperature change sensed by the temperature section is disposed, and a valve body that opens and closes the radiator cooling water path and the radiator bypass path. A second thermostat is provided ,
In the first thermostat, the temperature sensing part and the valve body are partitioned from each other and disposed in a water outlet member provided on the cooling water outflow side of the water jacket,
In the radiator bypass path, a pressure relief valve that opens above a predetermined water pressure is disposed,
Engine The engine cold start, characterized in that cooling water passage for the heater is closed by the valve body in the first thermostat, the cooling water passage for the radiator is found closed by the valve body and the second thermostat Cooling system. A cooling water passage for the exhaust gas recirculation device connected to the exhaust gas recirculation device is provided in parallel with the cooling water passage for the heater,
When the engine is cold started, the heater cooling water passage and the exhaust gas recirculation device cooling water passage are closed by the valve body while the temperature of the cooling water below a predetermined value is sensed by the temperature sensing portion of the first thermostat. The engine cooling device according to claim 1 .

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