JP2012117485A - Cooling device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling devic for an internal combustion engine capable of differentiating the operation timing of each thermostat while achieving the communalization of thermowax or the like of each thermostat.SOLUTION: In a two-system cooling device having first and second thermostats, the first thermostat 4 has a guide member 46 for changing the streamline of cooling water flowing in from a bypass flow passage 1f to a heat-sensing cylinder 41a. The second thermostat has the same constitution as that of the first thermostat 4, and its arrangement posture has the phase difference of 180° to the arrangement posture of the first thermostat 4. Thus, in the second thermostat, the flow of cooling water from a pump flow-out passage to a head side flow passage is not blocked by the guide member. Thus, the operation timing of the first thermostat 4 can be expedited and the operation timing of the second thermostat can be delayed.

Description

  The present invention relates to a cooling device that cools an internal combustion engine represented by an automobile engine or the like by circulation of cooling water. In particular, the present invention relates to an improvement of a cooling device including a plurality of thermostats.

  Conventionally, in an internal combustion engine for automobiles (hereinafter sometimes referred to as “engine”), a water jacket for a cylinder head (hereinafter also referred to as “head side water jacket”) and a water jacket for a cylinder block (hereinafter referred to as “block side”). An engine cooling device (generally called a “two-system cooling device”) in which cooling water is circulated in parallel has been proposed (for example, the following patent) Reference 1 and Patent Reference 2).

  In this type of cooling device, for example, when the engine is cold started (cold start), the cooling water is supplied to the head side water jacket while the cooling water supply to the block side water jacket is stopped. Yes. This makes it possible to quickly increase the temperature of the cylinder block while suppressing an excessive increase in the temperature of the cylinder head, and to reduce the friction loss at various points in the engine within a short period after the engine is started. The fuel consumption rate can be improved.

  In addition, as an example of this dual cooling system, two thermostats are provided, and the operation timing of these thermostats is made different so that the cooling to the head side water jacket is stopped while the supply of cooling water to the block side water jacket is stopped. There is one that switches between a state in which water is supplied and a state in which cooling water is supplied to both water jackets.

  Specifically, first and second thermostats are provided. The first thermostat can be switched between a first state in which the cooling water derived from the engine flows by bypassing the radiator and a second state in which the coolant flows through the radiator. On the other hand, the second thermostat is between the first state in which the cooling water discharged from the water pump flows through the head side water jacket without flowing into the block side water jacket and the second state through which the water jacket flows through both water jackets. Switching is possible. When the engine is cold started, both the thermostats are set to the first state, and when the cooling water temperature reaches the first predetermined temperature, the first thermostat is set to the second state and the cooling water cooling function by the radiator is performed. Make it work. Thereafter, when the cooling water temperature reaches the second predetermined temperature, the second thermostat is set to the second state so that the cooling water cooled by the radiator flows to both water jackets, and the temperature of the cylinder head and the cylinder block is adjusted. It tries to optimize.

  In addition, the general thermostat used for the cooling device mentioned above has a temperature sensitive cylinder arrange | positioned in cooling water. A thermo wax that expands and contracts in accordance with the heat of the cooling water transmitted through the wall of the temperature sensing cylinder is accommodated in the temperature sensing cylinder. And it is set as the structure which can switch the said 1st state and 2nd state according to the expansion | swelling and shrinkage | contraction of this thermowax (for example, refer the following patent document 3).

JP 59-215915 A JP 2008-133772 A JP 09-158725 A

  As described above, a plurality of thermostats are arranged in the cooling water circulation circuit, and in order to make the operation timings of these thermostats different, those having different expansion characteristics can be used as the thermowax used in each thermostat. It has been necessary to use coil springs having different urging forces as coil springs that impart urging force to the valve body in the thermostat.

  However, when thermostats having different configurations are used as described above, it is necessary to individually design and manufacture the thermostats, which not only deteriorates productivity but also increases manufacturing costs. Also, depending on how the cooling water flows around the temperature sensing cylinder containing the thermo wax, the thermostat operating timing may deviate from the desired timing, and the cooling water temperature cannot be adjusted to an appropriate value. There was also.

  The present invention has been made in view of the above points, and the object of the present invention is to share the thermowax and the like in each thermostat with respect to the cooling device in which a plurality of thermostats are arranged in the cooling water circulation circuit. An object of the present invention is to provide a cooling apparatus for an internal combustion engine that can vary the operation timing of each thermostat.

-Principle of solving the problem-
The solution principle of the present invention devised to achieve the above object is that the flow of the cooling water inside the thermostat can be guided by the guide member, and in the thermostat that should come early in the operation timing, the cooling toward the heat sensitive part is performed. While a flow of water (relatively high temperature cooling water) is generated, in a thermostat whose operation timing should be delayed with respect to the thermostat, a flow of cooling water toward the heat sensitive portion is not generated. Also, by making each thermostat's installation posture different from each other, it is possible to obtain a state where the guide function by the guide member is exhibited and a state where it is not exhibited by each thermostat, so that the configuration of each thermostat is made common Can be planned.

-Solution-
Specifically, according to the present invention, an in-head cooling water flow path is provided in a cylinder head of an internal combustion engine, and an in-block cooling water flow path is provided in a cylinder block, and the temperature of the cooling water flowing around the heat sensitive part is set to a predetermined temperature. A first thermostat and a second thermostat for switching the valve body from a closed state to an open state when the valve body is reached, and when the valve body of the first thermostat is in an open state and the valve body of the second thermostat is in a closed state The cooling water circulation state in which the cooling water flows through only one of the in-head cooling water flow channel and the in-block cooling water flow channel, while the valve bodies of the first thermostat and the second thermostat are both open, A cooling device for an internal combustion engine configured to be in a cooling water circulation state in which cooling water flows through both the cooling water flow channel and the cooling water flow channel in the block. Hisage to. For the internal combustion engine cooling device, the first thermostat is provided with a guide member that guides the cooling water flowing from the cooling water inlet to the cooling water outlet when the valve body is in the closed state, to the heat sensitive part, The second thermostat has a configuration in which a guide member is provided at a position that does not hinder the flow of cooling water flowing from the cooling water inlet to the cooling water outlet when the valve body is in a closed state.

  Due to this specific matter, when the valve bodies of the first thermostat and the second thermostat are both closed, in the first thermostat, the cooling water flowing from the cooling water inlet to the cooling water outlet is guided around the heat sensitive part by the guide member. Led. That is, relatively high-temperature cooling water (cooling water received from the internal combustion engine) flows around the heat-sensitive part of the first thermostat, and the operation timing of the first thermostat (the valve body changes from the closed state to the open state). The timing of switching will be reached early. On the other hand, in the second thermostat, the flow of cooling water from the cooling water inlet to the cooling water outlet is not hindered by the guide member. That is, there is relatively low-temperature cooling water around the heat-sensitive part of the second thermostat, and the operation timing of the second thermostat (timing for switching the valve body from the closed state to the open state) is the above-mentioned first. It will be delayed with respect to the operation timing of the thermostat.

  Due to the difference in the operation timings of the first thermostat and the second thermostat, only the valve body of the first thermostat is first opened during the cooling water circulation, and the cooling water flow path in the head and in the block are first opened. A cooling water circulation state in which the cooling water is supplied to only one of the cooling water flow paths is established. Thereafter, the valve body of the second thermostat is also opened, and a cooling water circulation state in which the cooling water flows through both the in-head cooling water flow path and the in-block cooling water flow path is set.

  As described above, in the present solution, the flow of the cooling water inside each thermostat is made different from each other, thereby causing a difference in the operation timing of each thermostat. For this reason, it becomes possible to make a difference in the operation timing while making the thermowax used for each thermostat and the coil spring which gives urging force to the valve body common. In other words, it is possible to realize two-system cooling (a cooling system that can individually adjust the cooling performance for the cylinder head and the cooling performance for the cylinder block) while using a plurality of thermostats having the same configuration.

  Specific examples of the circulating operation of the cooling water according to the operating state of each thermostat include the following. That is, the first thermostat has a first cooling water inlet communicating with the head cooling water flow path and the block cooling water flow path, a second cooling water inlet communicating with the outlet side of the radiator, and a water pump inlet. A cooling water outlet that communicates with the cooling water outlet. On the other hand, a cooling water inlet that communicates with the discharge port of the water pump, a first cooling water outlet that communicates with the cooling water flow path in the head, and a second cooling water flow that communicates with the cooling water flow path within the block. With an exit. When the valve body of the first thermostat is in a closed state, the second cooling water inlet is closed, the first cooling water inlet and the cooling water outlet are communicated, and the valve body of the first thermostat is In the open state, each cooling water inlet and the cooling water outlet communicate with each other. On the other hand, when the valve body of the second thermostat is in a closed state, the second cooling water outlet is closed, the cooling water inlet and the first cooling water outlet communicate, and the valve body of the second thermostat is In the open state, the cooling water inlet and each cooling water outlet communicate with each other.

  First, when the valve body of the first thermostat is in a closed state, the first cooling water inlet and the cooling water outlet communicate. Since the first cooling water inlet is in communication with the head cooling water channel and the block cooling water channel, the first cooling water inlet receives heat by flowing through the cooling water channel (specifically, the head cooling water channel) and increases the temperature. The resulting cooling water flows into the first thermostat from the first cooling water inlet. And in this 1st thermostat, the cooling water is guide | induced to the heat-sensitive part periphery by the guide member. For this reason, the operation timing of the first thermostat is reached early. On the other hand, when the valve body of the second thermostat is in the closed state, the cooling water inlet and the first cooling water outlet communicate. Since the flow of the cooling water from the cooling water inlet to the first cooling water outlet is not hindered by the guide member, there should be relatively low temperature cooling water around the heat sensitive part of the second thermostat. Thus, the operation timing of the second thermostat is delayed with respect to the operation timing of the first thermostat.

  Specific examples of the arrangement posture of each thermostat include the following. The outflow direction of the cooling water from the cooling water outlet in the first thermostat and the outflow direction of the cooling water from the first cooling water outlet in the second thermostat are the same direction, and each thermostat has the same configuration. The arrangement postures are arranged with a phase difference of 180 °.

  According to this configuration, only the first thermostat and the second thermostat having the same structure are arranged with a phase difference of 180 °, thereby causing a difference in the operation timing of each thermostat. be able to. That is, even though the thermostat is one type, the functions of the thermostats can be made different so that the productivity can be improved and the manufacturing cost can be reduced.

  Specific examples of the operation when the valve body of the thermostat changes from the closed state to the open state include the following. That is, when the valve body of the first thermostat is tilted from the closed state to the open state, the side closer to the cooling water outlet is opened earlier than the far side.

  More specifically, a biasing force in the closing direction is applied to the valve body of the first thermostat by a coil spring. The coil spring of the first thermostat is brought into contact with the valve body on the side far from the cooling water outlet, and is separated from the valve body on the side near the cooling water outlet.

  According to this configuration, when the valve body of the first thermostat is changed from the closed state to the open state, most of the cooling water newly flowing into the first thermostat in accordance with the open state is obtained by the heat sensitive part. It will be derived from the cooling water outlet without flowing around. For this reason, for example, when new cooling water cooled by the radiator flows into the first thermostat, the heat sensitive part is suppressed from being cooled, the open state of the valve body is maintained, and the temperature of the internal combustion engine is appropriately adjusted. Will be adjusted.

  In the second thermostat, when the valve body of the second thermostat is tilted from the closed state to the open state, the side far from the cooling water outlet is opened earlier than the near side.

  More specifically, a biasing force in the closing direction is applied to the valve body of the second thermostat by a coil spring. The coil spring of the second thermostat is brought into contact with the valve body on the side close to the cooling water outlet, and is separated from the valve body on the side far from the cooling water outlet.

  In the present invention, the flow of the cooling water inside the thermostat can be guided by the guide member, and in the thermostat that should reach the operation timing early, the flow of the cooling water toward the heat sensitive part is generated, while the operation is performed with respect to the thermostat. In the thermostat whose timing should be delayed, the flow of the cooling water toward the heat sensitive part is not generated. For this reason, it becomes possible to make a difference in the operation timing while making the thermowax used for each thermostat and the coil spring which gives urging force to the valve body common.

It is a figure which shows typically the cooling water circulation circuit of the cooling device which concerns on embodiment. It is sectional drawing which shows a 1st thermostat and the cooling water channel of the peripheral part. It is a perspective view which shows a guide member. FIG. 3 is a view corresponding to FIG. 2 showing a state where the first thermostat is opened. It is sectional drawing which shows a 2nd thermostat and the cooling water channel of the peripheral part. FIG. 6 is a view corresponding to FIG. 5 showing a state where the second thermostat is opened. It is a cooling water circulation circuit diagram for demonstrating the cooling water circulation state at the time of cold start. It is a cooling water circulation circuit diagram for demonstrating the cooling water circulation state in the state which the 1st thermostat opened. It is a figure which shows the change of the exit temperature of each thermostat.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a case where the present invention is applied to a cooling device mounted on an automobile engine (internal combustion engine) will be described. Further, in the present embodiment, a case will be described in which the present invention is applied to a two-system cooling device in which the cooling water flow path inside the cylinder head of the engine and the cooling water flow path inside the cylinder block are independent from each other.

-Cooling water circulation circuit-
FIG. 1 is a diagram schematically showing a cooling water circulation circuit 1 of the cooling device according to the present embodiment. The engine E cooled by the cooling water circulating through the cooling water circulation circuit 1 includes a cylinder head 2 and a cylinder block 3. An in-head cooling water channel 2 a is formed inside the cylinder head 2, and an in-block cooling water channel 3 a is formed inside the cylinder block 3.

  Further, a water pump P is connected to a crankshaft (not shown) that is an output shaft of the engine E, and the water pump P operates by receiving the rotational driving force of the crankshaft. .

  A first thermostat 4 is connected to the upstream side (suction side) of the water pump P via a pump inflow passage 1a. That is, the outlet 4C (cooling water outlet) of the first thermostat 4 is connected to the suction side of the water pump P. A second thermostat 5 is connected to the downstream side (discharge side) of the water pump P via a pump outflow passage 1b. That is, the inlet 5A (cooling water inlet) of the second thermostat 5 is connected to the discharge side of the water pump P.

  The second thermostat 5 is provided with first and second outlets 5B and 5C. The first outlet 5B (the outlet on the right side in the figure: the first cooling water outlet) is connected to the in-head cooling water channel 2a via the head side channel 1c. Further, the second outlet 5C (upper outlet in the drawing: second cooling water outlet) is connected to the in-block cooling water flow path 3a via the block side flow path 1d.

  On the other hand, the first thermostat 4 is provided with first and second inflow ports 4A and 4B. The first inlet 4A (lower inlet in the figure: first cooling water inlet) is connected to a return channel 1g described later via a bypass channel 1f. Further, the second inlet 4B (upper inlet in the figure: second cooling water inlet) is connected to the lower tank of the radiator 6 via the radiator-side channel 1e.

  The return channel 1g has a downstream end connected to the upper tank of the radiator 6, while an upstream end is branched, one is a head side branch channel 1h, and the other is a block side branch channel 1i. The head side branch flow path 1h is connected to the in-head cooling water flow path 2a, and the block side branch flow path 1i is connected to the in-block cooling water flow path 3a.

  The cooling water circulation circuit 1 is provided with a heater 7 and an EGR cooler 8. The heater 7 is used to heat the passenger compartment air by exchanging heat between the cooling water and the passenger compartment air during heating of the passenger compartment. On the other hand, the EGR cooler 8 is used to cool the EGR gas by exchanging heat between the EGR gas recirculated from the exhaust system of the engine E to the intake system and the cooling water.

  A branch flow path 1j is connected between the return flow path 1g and the pump inflow path 1a, and the heater 7 and the EGR cooler 8 are arranged in parallel in the branch flow path 1j. An on-off valve 7 a is provided on the upstream side of the heater 7. The on-off valve 7a is opened when the vehicle interior is requested to heat and allows cooling water to flow through the heater 7 so that heat can be exchanged between the cooling water and the vehicle interior air.

  Hereinafter, the configuration and function of each device constituting the cooling water circulation circuit 1 will be briefly described.

  The radiator 6 is of a downflow type, and a radiator core is provided between the upper tank and the lower tank. As a result, the cooling water collected in the upper tank from the engine E via the return flow path 1g flows into the radiator core toward the lower tank, and heat is generated between the outside air (running wind and air blown by driving the cooling fan). The cooling water is cooled by exchanging and dissipating heat to the outside air.

  Each of the thermostats 4 and 5 adjusts the temperature of the cooling water by switching the water channel of the cooling water circulation circuit 1, and uses the thermal expansion of the thermowax sealed inside, and the built-in valve serves as the cooling water. It has a mechanism that opens and closes according to temperature. The specific structure of these thermostats 4 and 5 and the flow of cooling water accompanying the opening and closing of the valves will be described later.

  The water pump P is for generating a water flow in the cooling water circulation circuit 1, and a transmission belt is stretched between a water pump pulley and a crankshaft pulley provided on the drive shaft. In response to the rotational force of the crankshaft, it is driven.

  As described above, the heater 7 is for heating the passenger compartment using the heat of the cooling water, and faces the air duct of the air conditioner. In other words, air-conditioning air flowing in the air duct is passed through the heater 7 and supplied as warm air to the vehicle interior when heating the vehicle interior, while the air-conditioning air bypasses the heater 7 in other cases (for example, during cooling). ing.

  The EGR cooler 8 cools the EGR gas by exchanging heat between the EGR gas recirculated from the exhaust system of the engine E to the intake system and the cooling water as described above. That is, by cooling the EGR gas, its density is lowered, and the effect of lowering the combustion temperature by recirculating the EGR gas is promoted.

-Configuration of thermostats 4 and 5-
Next, the structure of each thermostat 4 and 5 is demonstrated. Since the configurations of the thermostats 4 and 5 are substantially the same, the configuration of the first thermostat 4 will be mainly described below.

(First thermostat 4)
FIG. 2 is a cross-sectional view showing the first thermostat 4 and the cooling water passage around the first thermostat 4. As shown in FIG. 2, the first thermostat 4 mainly includes a thermo actuator 41, a valve (valve element) 42, first and second frames 43 and 44, and a return spring 45.

  The thermoactuator 41 is a driving means for detecting the temperature change of the cooling water and opening / closing the valve 42. Specifically, the thermoactuator 41 has a cylindrical, lid-shaped guide member 41b attached to an opening (upper opening) of a bottomed cylindrical heat-sensitive cylinder (heat-sensitive part) 41a. With the push rod 41c inserted, one end in the longitudinal direction of the push rod 41c is projected from the center hole of the guide member 41b to the outside of the thermal cylinder 41a. A space formed between the elastic seal spool 41d attached to the guide member 41b and the inner wall surface of the thermal cylinder 41a is filled with a thermowax 41e.

  The thermowax 41e changes to a state of solidification and shrinkage or a state of melting and expansion depending on the temperature, and generally known ones can be used.

  A valve 42 is attached to the upper part of the thermal cylinder 41a via the guide member 41b. The valve 42 is formed in a disc shape, and a rubber 42 a is attached to the outer periphery of the valve 42 in order to maintain a state in which the valve 42 is in contact with the lower end opening edge of the annular flange 43 a of the first frame 43.

  The thermoactuator 41 is attached to the first and second frames 43 and 44 coupled to each other, the protruding end of the push rod 41 c is fixed to the center of the first frame 43, and the thermal cylinder 41 a is relative to the second frame 44. It is supported so that it can be displaced. The combined body of the first and second frames 43 and 44 has a shape that does not hinder the flow of the cooling water.

  A return spring 45 made of a coil spring is interposed between the valve 42 and the second frame 44 in an elastically compressed state. The return spring 45 exerts a function of closing the inner hole of the annular flange portion 43 a by pressing the valve 42 against the annular flange portion 43 a of the first frame 43 by its elastic restoring force.

  As a characteristic feature of the present embodiment, the first thermostat 4 is provided with a guide member 46 for guiding the flow of cooling water therein. Hereinafter, the guide member 46 will be described.

  FIG. 3 is a perspective view showing the guide member 46. As shown in FIGS. 2 and 3, the guide member 46 is made of a metal plate having a substantially semicircular cross section, and the pump inflow passage 1 a side (the first thermostat 4) on the lower surface of the second frame 44. Is attached to the outlet 4C side). Further, the mounting state is such that the center point of the semicircular arc of the cross section of the guide member 46 is located on the central axis of the thermoactuator 41. Furthermore, the height dimension of the guide member 46 substantially matches the dimension between the lower surface of the second frame 44 and the bottom surface of the pump inflow passage 1a, or the lower surface of the second frame 44 and the pump inflow. It is set slightly shorter than the dimension between the bottom surface of the path 1a. By providing such a guide member 46, when the cooling water flows from the bypass flow path 1f toward the pump inflow passage 1a, the flow line of the cooling water flowing from the bypass flow path 1f is guided by the guide member. 46 (refer to the flow of cooling water indicated by a one-dot chain line arrow A in the figure). That is, the cooling water flows toward the thermal cylinder 41a, flows around the thermal cylinder 41a, passes through the upper side of the guide member 46, and is led out to the pump inflow passage 1a.

  The cooling water flowing from the bypass flow path 1f is discharged from the in-head cooling water flow path 2a of the engine E (cylinder head 2) (from the in-head cooling water flow path 2a toward the first thermostat 4). The circulating operation of the cooling water will be described later), and the temperature of the cylinder head 2 is relatively high due to the heat of the cylinder head 2. For this reason, by the change of the coolant flow by the guide member 46 (change of the coolant flow in the direction toward the thermal cylinder 41a), the relatively high temperature of the coolant is caused to flow toward the thermal cylinder 41a. The thermal expansion of the thermowax 41e filled in the thermal cylinder 41a is promoted. That is, the first thermostat 4 has a configuration in which the operation timing of the valve 42 is reached early by changing the coolant flow by the guide member 46.

  The upper end edge of the return spring 45 is separated from the lower surface of the valve 42 on the side where the guide member 46 is disposed (the right side in FIG. 2), while the lower surface of the valve 42 is on the opposite side (the left side in FIG. 2). Abut. Therefore, the urging force of the return spring 45 against the valve 42 when the valve 42 is in the closed state is low on the side where the guide member 46 is disposed (the right side in FIG. 2). On the left side in FIG. For this reason, when the valve 42 is opened along with the melt expansion of the thermowax 41e, the side where the urging force of the return spring 45 is small, that is, the position where the guide member 46 is disposed (the right side in FIG. 2) comes first. It will begin to open. FIG. 4 is a cross-sectional view of the first thermostat 4 when the valve 42 starts to open. As shown in FIG. 4, the side where the urging force of the return spring 45 is small, that is, the position where the guide member 46 is disposed (the right side in FIG. 4) is open, whereas the position where the guide member 46 is disposed. The opposite side (left side in FIG. 4) is closed. In this state, the flow of the cooling water flowing from the radiator side flow path 1e is indicated by a one-dot chain line arrow B in the figure.

  The operation of the first thermostat 4 configured as described above will be described.

  First, when the temperature of the cooling water flowing into the first thermostat 4 from the bypass flow path 1f is equal to or lower than a predetermined set temperature (for example, 80 ° C.), the thermowax 41e is solidified and contracted, and the thermowax pressure is low. Therefore, the elastic seal spool 41d is expanded to increase the fitting depth of the thermal cylinder 41a to the push rod 41c, and the return spring 45 is extended, so that the valve 42 is connected to the annular flange portion 43a of the first frame 43. The inner hole of the annular flange portion 43a is closed by pressing. In this state, the cooling water introduced from the cooling water flow path 2a of the engine E (more specifically, the cylinder head 2) to the head side branch flow path 1h and the bypass flow path 1f is indicated by a one-dot chain line arrow A in FIG. Thus, it will flow to the pump inflow passage 1a.

  On the other hand, when the temperature of the cooling water flowing into the first thermostat 4 from the bypass flow path 1f exceeds a predetermined set temperature, the thermowax 41e is melted and expanded to increase the thermowax pressure, so that the elastic seal spool 41d is throttled. As a result, the fitting depth of the push rod 41c with respect to the heat sensitive cylinder 41a is reduced, the return spring 45 is elastically compressed, and the valve 42 is pulled away from the annular flange portion 43a of the first frame 43. The inner hole of the portion 43a is opened.

  In the initial stage of the opening operation of the valve 42, as described above, the urging force of the return spring 45 against the valve 42 is not uniform in the circumferential direction, so that the urging force of the return spring 45 is smaller, that is, the guide member. The arrangement position side 46 (the right side in FIG. 4) begins to open first, and the cooling water flows as shown by a one-dot chain line arrow B in FIG.

  When the valve 42 is opened in this way, the cooling water cooled by the radiator 6 from the cooling water flow path 2a of the engine E (more specifically, the cylinder head 2) through the return flow path 1g becomes the radiator side flow path. 1e flows into the first thermostat 4 and is mixed with the cooling water introduced from the bypass flow path 1f and flows to the pump inflow path 1a.

(Second thermostat 5)
FIG. 5 is a cross-sectional view showing the second thermostat 5 and the cooling water channel in the periphery thereof. As shown in FIG. 5, the second thermostat 5 mainly includes a thermo actuator 51, a valve (valve element) 52, first and second frames 53 and 54, and a return spring 55. Since the configuration of each of these members is the same as that of the first thermostat 4 described above, description thereof is omitted here. In FIG. 5, the same members as those indicated by reference numerals 41 a to 41 e, 42 a and 43 a in FIG. 2 are denoted by reference numerals 51 a to 51 e, 52 a and 53 a.

  The second thermostat 5 is characterized in that the second thermostat 5 is installed in a posture rotated by 180 ° with respect to the arrangement posture of the first thermostat 4. That is, even in the second thermostat 5, the guide member 56 is provided in the same manner as the first thermostat 4, but the guide member 56 is disposed on the lower surface of the second frame 54. The head side flow path 1c side (the 1st outflow port 5B side of the 2nd thermostat 5) is attached to the opposite side. When the guide member 56 is disposed at such a position, when the cooling water flows from the pump outflow passage 1b toward the head-side passage 1c, the flow line of the cooling water is blocked by the guide member 56. There is nothing. That is, the flow direction of the cooling water is not changed by the guide member 56, and most of the cooling water is led out to the head side flow path 1c without flowing around the heat sensitive cylinder (heat sensitive part) 51a. (Refer to the flow of cooling water indicated by the dashed line arrow C in the figure). For this reason, the melt expansion of the thermowax 51e filled in the thermal cylinder 51a is limited. That is, the second thermostat 5 is configured such that the operation timing of the valve 52 is delayed with respect to the operation timing of the valve 42 of the first thermostat 4 because the cooling water flow is not changed by the guide member 56. It has become.

  Further, the upper end edge of the return spring 55 in the second thermostat 5 is separated from the lower surface of the valve 52 on the side where the guide member 56 is disposed (left side in FIG. 5), but on the opposite side (right side in FIG. 5). Then, it contacts the lower surface of the valve 52. For this reason, when the valve 52 is in the closed state, the urging force of the return spring 55 against the valve 52 is low on the side where the guide member 56 is disposed (left side in FIG. 5). On the right side in FIG. For this reason, when the valve 52 is opened as the thermowax 51e melts and expands, the side where the urging force of the return spring 55 is small, that is, the position where the guide member 56 is disposed (the left side in FIG. 5) comes first. It will begin to open. FIG. 6 is a cross-sectional view of the second thermostat 5 when the valve 52 starts to open. As shown in FIG. 6, the side where the biasing force of the return spring 55 is small, that is, the position where the guide member 56 is disposed (the left side in FIG. 6) is open, whereas the position where the guide member 56 is disposed. The opposite side (right side in FIG. 6) is closed. The flow of the cooling water flowing out to the block-side flow path 1d in such a state is indicated by a one-dot chain line arrow D in the drawing.

  The operation of the second thermostat 5 configured as described above will be described.

  First, when the temperature of the cooling water flowing into the second thermostat 5 from the pump outflow passage 1b is equal to or lower than a predetermined set temperature, the thermowax 51e is solidified and contracted, and the thermowax pressure is low. 51d spreads and the fitting depth of the thermosensitive cylinder 51a to the push rod 51c is deepened, and the return spring 55 is extended to press the valve 52 against the annular flange portion 53a of the first frame 53. The inner hole of the annular flange portion 53a is closed. In this state, the cooling water introduced from the pump outflow passage 1b flows to the head side flow passage 1c as shown by a one-dot chain line arrow C in FIG.

  On the other hand, when the temperature of the cooling water around the thermal cylinder 51a exceeds a predetermined set temperature, the thermowax 51e is melted and expanded, and the thermowax pressure is increased. As the fitting depth of 51c decreases, the return spring 55 is elastically compressed, and the valve 52 is pulled away from the annular flange portion 53a of the first frame 53 to open the inner hole of the annular flange portion 53a. To do.

  In the initial stage of the opening operation of the valve 52, as described above, the urging force of the return spring 55 against the valve 52 is not uniform in the circumferential direction, so that the urging force of the return spring 55 is smaller, that is, the guide member. The arrangement position side 56 (the left side in FIG. 6) begins to open first, and the cooling water flows as shown by a one-dot chain line arrow D in FIG. In this way, the cooling water introduced from the pump outflow passage 1b is divided into the head side flow passage 1c and the block side flow passage 1d as indicated by alternate long and short dashed arrows C and D in FIG. It will flow into the path 2a and the in-block cooling water flow path 3a.

−Cooling water circulation operation−
Next, the cooling water circulation operation in the cooling water circulation circuit 1 configured as described above will be described. Here, when the engine E is cold started and the valves 42 and 52 of the thermostats 4 and 5 are both closed (the state shown in FIGS. 2 and 5), the cooling water temperature rises and reaches a predetermined temperature. A state where the valve 42 of the first thermostat 4 is opened (state shown in FIG. 4) and a state where the valve 52 of the second thermostat 5 is opened thereafter (state shown in FIG. 6) will be described.

(At cold start)
FIG. 7 is a cooling water circulation circuit diagram showing a cooling water circulation state at the time of cold start, and a flow path through which the cooling water flows is indicated by a solid line, and a flow path through which the cooling water does not flow is indicated by a broken line.

  As shown in FIG. 7, at the time of cold start, since the coolant temperature is low, the valves 42 and 52 of the first thermostat 4 and the second thermostat 5 are both closed. That is, in the first thermostat 4, the second inlet 4B is in a closed state, the first inlet 4A and the outlet 4C communicate, and the bypass channel 1f and the pump inlet 1a communicate. Further, in the second thermostat 5, the second outlet 5C is in a closed state, the inlet 5A and the first outlet 5B communicate with each other, and the pump outlet passage 1b and the head side passage 1c communicate with each other. .

  In this case, the cooling water discharged from the water pump P flows into the in-head cooling water flow path 2a through the pump outflow path 1b, the second thermostat 5, and the head side flow path 1c. Thereby, the cylinder head 2 is cooled. The cooling water that has passed through the in-head cooling water flow path 2a is sucked into the water pump P via the head side branch flow path 1h, the return flow path 1g, the bypass flow path 1f, the first thermostat 4, and the pump inflow path 1a. By such cooling water circulation operation, it is possible to suppress an excessive increase in the temperature of the cylinder head 2 by flowing the cooling water to the in-head cooling water flow path 2a, and not to flow the cooling water to the in-block cooling water flow path 3a. The temperature of the cylinder block 3 is increased immediately.

(First thermostat 4 opened)
FIG. 8 is a cooling water circulation circuit diagram showing a cooling water circulation state in the open state of the first thermostat 4 (open state of the valve 42). The flow path through which the cooling water flows is shown by a solid line, and the cooling water is not flowing. The flow path is indicated by a broken line.

  When the coolant temperature rises from the cold start state and reaches a predetermined temperature and the valve 42 of the first thermostat 4 is opened (see FIG. 4), the second inlet 4B is opened, and the first The inflow port 4A, the second inflow port 4B, and the outflow port 4C communicate with each other, and the radiator-side flow path 1e and the pump inflow path 1a communicate with each other.

  In this case, in addition to the flow of the cooling water at the time of the cold start described above, a part of the cooling water flowing through the return flow path 1g is introduced into the radiator 6, cooled by the radiator 6, and then the radiator side flow path. A flow of flowing into the second inlet 4B of the first thermostat 4 through 1e occurs. Thus, while the temperature of the cylinder block 3 is rapidly increased, the temperature of the cylinder head 2 is appropriately maintained by releasing the heat recovered from the cylinder head 2 into the atmosphere.

(When warm-up is complete)
FIG. 1 is a cooling water circulation circuit diagram showing a cooling water circulation state when the second thermostat 5 is in an open state (the valve 52 is in an open state) when the warm-up is completed. The road is shown as a solid line.

  When the warm-up is completed and the valve 52 of the second thermostat 5 is opened (see FIG. 6), the second outlet 5C is opened, and the inlet 5A, the first outlet 5B, and the second outlet 5C are opened. The pump outflow passage 1b and the block side flow passage 1d communicate with each other.

  In this case, in addition to the flow of the cooling water in the open state of the first thermostat 4 described above, a part of the cooling water passing through the second thermostat 5 flows into the in-block cooling water flow path 3a via the block side flow path 1d. To do. Thereby, the cylinder block 3 is cooled. The cooling water that has passed through the in-block cooling water flow path 3a passes through the block-side branch flow path 1i, and then merges with the cooling water led out from the cylinder head 2 in the return flow path 1g and flows toward the radiator 6. Will occur. As a result, cooling water is supplied to both the cylinder head 2 and the cylinder block 3 to optimize these temperatures.

  In any of the above-described cooling water circulation operations, the cooling water flows through the branch flow path 1j. If necessary, heat exchange with the cabin air in the heater 7 and heat with the EGR gas in the EGR cooler 8 are performed. An exchange has been made.

  FIG. 9 is a diagram illustrating an example of changes in the outlet temperatures of the thermostats 4 and 5 during the cooling water circulation operation described above. Here, the outlet temperature of each of the thermostats 4 and 5 is the cooling water temperature at the outlet 4C connected to the pump inflow passage 1a in the first thermostat 4 and is a block in the second thermostat 5. This is the cooling water temperature at the second outlet 5C connected to the side flow path 1d.

  First, at the time of cold start, the first thermostat 4 receives cooling water that has received heat from the cylinder head 2 and has reached a high temperature, and the cooling water flows out from the outlet 4C to the pump inlet passage 1a. The outlet temperature of 1 thermostat 4 increases rapidly. On the other hand, in the second thermostat 5, the second outlet 5C is closed by the valve 52, and high-temperature cooling water does not flow out of the second outlet 5C. Therefore, the outlet of the second thermostat 5 The rate of temperature rise is slow.

  When the temperature of the cooling water flowing around the thermal cylinder 41a of the first thermostat 4 reaches a predetermined temperature T1, the valve 42 of the first thermostat 4 is opened. As the valve 42 is opened, the cooling water cooled by the radiator 6 flows into the first thermostat 4, so that the outlet temperature is slightly lowered, and then controlled to a predetermined temperature. become.

  On the other hand, when the cooling water temperature existing around the thermosensitive cylinder 51a of the second thermostat 5 reaches a predetermined temperature T2, the valve 52 of the second thermostat 5 is opened. With the opening of the valve 52, A part of the cooling water that has flowed into the second thermostat 5 through the pump outflow passage 1b flows out from the second outlet 5C to the block-side passage 1d, so that the outlet temperature of the second thermostat 5 rapidly increases. To go. Thereafter, the outlet temperature is controlled to a predetermined temperature.

  As described above, in the present embodiment, the operation timing of each thermostat 4, 5 is made different from the position where the guide member 46 is disposed in the first thermostat 4 and the position where the guide member 56 is disposed in the second thermostat 5. Can make a difference. That is, by making the flows of the cooling water in the thermostats 4 and 5 different from each other, it is possible to make a difference in the operation timing of the thermostats 4 and 5. For this reason, the thermowax 41e and 51e used for each thermostat 4 and 5 and the return springs 45 and 55 giving the urging force to the valves 42 and 52 are made common, but a difference is caused in the operation timing. Is possible. As a result, it is possible to realize two-system cooling (a cooling system that can individually adjust the cooling performance for the cylinder head 2 and the cooling performance for the cylinder block 3) while using the thermostats 4 and 5 having the same configuration. Thus, productivity can be improved and manufacturing costs can be reduced.

-Other embodiments-
In the embodiment described above, the case where the present invention is applied to the cooling device mounted on the automobile engine E has been described. The present invention is not limited to this, and can also be applied to a cooling device mounted on an internal combustion engine other than an automobile engine.

  In the above-described embodiment, the case where the present invention is applied to the two-system cooling device in which the in-head cooling water channel 2a and the in-block cooling water channel 3a are independent from each other has been described. The present invention is not limited to this, and can also be applied to a cooling water circulation circuit in which a part of the cooling water flowing through the in-block cooling water channel 3a is introduced into the in-head cooling water channel 2a.

  In the above embodiment, at the time of cold start of the engine E, the cooling water is supplied to the in-head cooling water channel 2a while stopping the supply of the cooling water to the in-block cooling water channel 3a. The case where the cooling water is supplied to the cooling water flow paths 2a and 3a has been described. The present invention is not limited to this, and the cooling water is supplied to the in-block cooling water flow channel 3a in a state where the supply of the cooling water to the in-head cooling water flow channel 2a is stopped. The present invention can also be applied to a cooling device that supplies water.

  Further, in the above embodiment, the guide members 46 and 56 are attached to the lower surface of the second frame 44. The present invention is not limited to this, and may be attached to the wall surface of the cooling water flow path. The shapes of the guide members 46 and 56 are not limited to those described above, and any shape that can guide the flow of the cooling water around the thermal cylinder 41a in the first thermostat 4 may be used.

  The present invention is applicable to a cooling device for sharing a thermostat with respect to a two-system cooling device that includes two thermostats and has a cooling water flow path that is independent of each of the cylinder head and the cylinder block.

DESCRIPTION OF SYMBOLS 1 Cooling water circulation circuit 2 Cylinder head 2a Head cooling water flow path 3 Cylinder block 3a Block cooling water flow path 4 1st thermostat 5 2nd thermostat 41a, 51a Thermal cylinder (thermal part)
42,52 Valve (Valve)
45, 55 Return spring (coil spring)
46, 56 guide member 4A first inlet (first cooling water inlet)
4B Second inlet (second cooling water inlet)
4C outlet (cooling water outlet)
5A inlet (cooling water inlet)
5B first outlet (first cooling water outlet)
5C Second outlet (second cooling water outlet)
6 Radiator E engine (internal combustion engine)
P Water pump

Claims (7)

An internal coolant flow path is provided in the cylinder head of the internal combustion engine, and an internal block coolant flow path is provided in the cylinder block, and the valve body closes when the temperature of the coolant flowing around the heat sensitive part reaches a predetermined temperature. A first thermostat and a second thermostat that are switched from a state to an open state, and when the valve body of the first thermostat is in an open state and the valve body of the second thermostat is in a closed state, While the cooling water circulation state in which the cooling water is supplied to only one of the in-block cooling water flow paths, and when the valve bodies of the first thermostat and the second thermostat are both open, the in-head cooling water flow path and the in-block cooling water flow In the cooling device for an internal combustion engine configured to be in a cooling water circulation state in which cooling water flows through both of the paths,
The first thermostat is provided with a guide member that guides the cooling water flowing from the cooling water inlet to the cooling water outlet when the valve body is in the closed state to the heat sensitive part, while the second thermostat is provided with the second thermostat. A cooling device for an internal combustion engine, characterized in that a guide member is provided at a position that does not hinder the flow of cooling water flowing from the cooling water inlet to the cooling water outlet when the valve body is in a closed state. The cooling apparatus for an internal combustion engine according to claim 1,
The first thermostat communicates with a first cooling water inlet communicating with the head cooling water channel and the block cooling water channel, a second cooling water inlet communicating with the outlet side of the radiator, and a water pump suction port. The second thermostat includes a cooling water inlet that communicates with the discharge port of the water pump, a first cooling water outlet that communicates with the cooling water flow path in the head, and a cooling water flow within the block. A second cooling water outlet that communicates with the road,
When the valve body of the first thermostat is in a closed state, the second cooling water inlet is closed, the first cooling water inlet and the cooling water outlet are communicated, and the valve body of the first thermostat is open. The cooling water inlet and the cooling water outlet communicate with each other,
When the valve body of the second thermostat is in a closed state, the second cooling water outlet is closed, the cooling water inlet and the first cooling water outlet are communicated, and the valve body of the second thermostat is open. In such a case, the cooling device for an internal combustion engine, wherein the cooling water inlet and each cooling water outlet are in communication with each other. The cooling apparatus for an internal combustion engine according to claim 2,
The outflow direction of the cooling water from the cooling water outlet in the first thermostat and the outflow direction of the cooling water from the first cooling water outlet in the second thermostat are the same direction, and each thermostat has the same configuration. A cooling device for an internal combustion engine, wherein the arrangement postures are arranged with a phase difference of 180 °. The cooling device for an internal combustion engine according to claim 1, 2, or 3,
The cooling device for an internal combustion engine, wherein the first thermostat is configured such that when the valve body is inclined from the closed state to the open state, the side closer to the cooling water outlet is opened earlier than the far side. . The cooling apparatus for an internal combustion engine according to claim 4,
The valve body of the first thermostat is given a biasing force in the closing direction by a coil spring,
The cooling device for an internal combustion engine, wherein the coil spring of the first thermostat is in contact with the valve body on a side far from the cooling water outlet and is separated from the valve body on a side near the cooling water outlet. The cooling device for an internal combustion engine according to claim 1, 2, or 3,
The cooling device for an internal combustion engine, wherein the second thermostat is configured to be opened earlier than the side closer to the side farther from the cooling water outlet when the valve body is tilted from the closed state to the opened state. . The cooling device for an internal combustion engine according to claim 6,
The valve body of the second thermostat is provided with a biasing force in the closing direction by a coil spring,
The cooling device for an internal combustion engine, wherein the coil spring of the second thermostat is in contact with the valve body on the side close to the cooling water outlet, and is separated from the valve body on the side far from the cooling water outlet.

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