JP2012184693A - Cooling device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent degradation in the fuel consumption and reduction in the flow rate in a cylinder head as the supply of cooling water to a cylinder block of a two-system cooling device is started.SOLUTION: In a two-system cooling device, an outlet side of an in-head cooling water flow passage 2a is branched. One branch forms a first branched pipe 1c connected to a radiator flow passage 5A and a heater flow passage 6A, and the other branch forms a second branch pipe 1d connected to an in-block cooling water flow passage 3a. In a condition in which the supply of cooling water to the in-block cooling water flow passage 3a is stopped, and cooling water is supplied to the in-head cooling water flow passage 2a, when starting the supply of cooling water to the in-block cooling water flow passage 3a, a situation is avoided, in which cooling water flowing in the in-head cooling water flow passage 2a is heated hot, and flows into the in-block cooling water flow passage 3a, and the temperature of a cylinder block 3 is rapidly dropped. Thus, the fuel consumption rate is improved, and the reliability of an engine E is ensured.

Description

  The present invention relates to a cooling device that cools an internal combustion engine represented by an automobile engine or the like by circulating cooling water. In particular, the present invention relates to an improvement of an internal combustion engine provided with a cooling system that stops the flow of cooling water to a cylinder block during warm-up operation or the like.

  2. Description of the Related Art Conventionally, in an automobile internal combustion engine (hereinafter also referred to as “engine”), a water jacket for a cylinder head (hereinafter also referred to as “in-head cooling water flow path”) and a water jacket for a cylinder block (hereinafter referred to as “block”). An engine cooling device (generally called a “two-system cooling device (or two-system cooling system)”) that allows cooling water to flow in parallel to the “internal cooling water flow path”) It has been proposed (see, for example, Patent Documents 1 to 3 below).

  This type of cooling device includes a water pump that generates a water flow in the cooling water circulation circuit, and switches the flow path of the cooling water circulation circuit according to the cooling water temperature (the cooling water discharged from the water pump is used as the cooling water flow in the block). There is provided a thermostat that switches between a state of supplying to the cooling water flow path in the head without supplying to the passage and a state of supplying to the cooling water flow paths together.

  When the engine is cold started (cold start), the cooling water is supplied to the in-head cooling water passage while the supply of the cooling water to the in-block cooling water passage is stopped. 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.

  Further, when the cooling of the cylinder block is necessary because the cooling water temperature reaches a predetermined temperature, the cooling water is also supplied to the in-block cooling water flow path. In this case, the cooling water supplied to the in-block cooling water flow path is cooled by a radiator and passes through a thermostat and a water pump.

JP 2004-1000047 A JP 2008-133772 A JP 2004-52752 A

  By the way, in the above-described conventional two-system cooling device, when supply of cooling water to the cooling water flow path in the block is started from a state where the supply of cooling water to the cooling water flow path in the block is stopped. The relatively low temperature cooling water cooled by the radiator is supplied to the in-block cooling water flow path in which the relatively high temperature cooling water has accumulated. That is, the temperature of the cylinder block (particularly the bore wall temperature) is rapidly lowered by supplying the low-temperature cooling water to the cylinder block that has been at a high temperature due to the retention of the cooling water. It will be. For this reason, the friction loss may fluctuate or the amount of thermal deformation of the cylinder block may become non-uniform, so that the fuel consumption rate may deteriorate or the reliability of the engine may deteriorate due to thermal distortion. There was sex.

  Moreover, since the cooling water flow path in the head and the cooling water flow path in the block are parallel to each other, the supply of the cooling water to the cooling water flow path in the head is started with the start of the supply of the cooling water to the cooling water flow path in the block. As a result, the supply amount is reduced, and the cooling effect on the cylinder head may not be sufficiently exhibited.

  The present invention has been made in view of such a point, and an object of the present invention is to provide a cylinder for an internal combustion engine having a cooling system that stops the flow of cooling water to the cylinder block during warm-up operation or the like. An object of the present invention is to provide a cooling device for an internal combustion engine that can solve the above-mentioned problems when supplying cooling water to a block.

-Principle of solving the problem-
The solution principle of the present invention devised to achieve the above object is that, in the dual cooling system, when cooling water is supplied to the cooling water passage in the block, the temperature rises by flowing through the cooling water passage in the head. By supplying the cooling water, the cylinder block is prevented from being rapidly cooled, and the flow rate of the cooling water flowing through the in-head cooling water flow path is not reduced.

-Solution-
Specifically, the present invention provides a cooling device for an internal combustion engine including a cooling water flow path in a head provided in a cylinder head of the internal combustion engine and a cooling water circulation circuit having a cooling water flow path in a block provided in a cylinder block. Assumption. A cooling pump for the internal combustion engine, a water pump that discharges cooling water toward the inlet side of the cooling water flow path in the head, and cooling water that has passed through the cooling water flow path in the head from the water pump is cooled in the block. A block bypass flow path that bypasses the water flow path and flows into the water pump; a radiator flow path that causes the cooling water from the water pump to pass through the cooling water flow path in the head to flow into the water pump via the radiator; and The temperature of the cooling water circulating through the cooling water circulation circuit and the block flow path for flowing the cooling water from the water pump through the cooling water flow path in the head into the water pump via the cooling water flow path in the block is first. A first valve body that cuts off a supply of cooling water to the block flow path when the temperature is equal to or lower than a predetermined temperature, and the cooling water circulation circuit; When the temperature of the cooling water circulating is less than the second predetermined temperature, causing a thermostatic valve having a second valve element for blocking the supply of cooling water into the radiator passage. And the branch part which branches the cooling water supply path to the said block bypass flow path and the said radiator flow path, and the cooling water supply path to the said block flow path was provided in the exit side of the said cooling water flow path in a head. It is configured.

  In this case, the first predetermined temperature is set higher than the second predetermined temperature.

  Due to this specific matter, during the period when the internal combustion engine is cold-started and the temperature of the cooling water circulating through the cooling water circulation circuit is equal to or lower than the second predetermined temperature, the second valve body of the thermostat valve returns to the radiator flow path. The cooling water supply is cut off. That is, the cooling water temperature is raised early by not cooling the cooling water circulating through the cooling water circulation circuit by the radiator. In this case, since the temperature of the cooling water is equal to or lower than the first predetermined temperature, the supply of the cooling water to the block flow path is blocked by the first valve body of the thermostat valve. In other words, the temperature of the cylinder block is quickly increased by retaining the coolant in the cooling water flow path in the block, and the fuel consumption rate is reduced so that the friction loss can be reduced at various locations in the engine within a short period of time after the engine is started. It is trying to improve.

  Thereafter, when the temperature of the cooling water rises and exceeds the second predetermined temperature, the blocking of the cooling water to the radiator flow path by the second valve body is released. That is, supply of cooling water to the radiator flow path is started. As a result, the temperature of the cylinder head can be optimized by the cooling action of the radiator. Further, when the temperature of the cooling water exceeds the first predetermined temperature, the blocking of the cooling water to the block flow path by the first valve body is released. That is, the supply of cooling water to the in-block cooling water flow path is started. As a result, an excessive increase in the temperature of the cylinder block is suppressed.

  And when supply of the cooling water to the cooling water flow path in the block is started, the cooling water which is divided in the branching portion from the outlet side of the cooling water flow path in the head, that is, the cooling water flow path in the head The cooling water whose temperature has been increased by flowing through the block flows into the cooling water flow path in the block. For this reason, it is possible to avoid a situation in which the temperature of the cylinder block rapidly decreases, and it is possible to improve the fuel consumption rate and to ensure the reliability of the internal combustion engine by preventing thermal distortion. In addition, since the amount of cooling water supplied to the cooling water flow path in the head does not decrease, the cooling capacity for the cylinder head can be sufficiently exerted even after the operation of supplying cooling water to the cooling water flow path in the block is started. In particular, reliability at a high water temperature can be sufficiently ensured.

  Specific examples of the thermostat valve include the following. In other words, the first and second valve bodies of the thermostat valve are respectively connected to the thermoactuator so that the valve closing state and the valve opening state are switched according to the movement stroke of the thermoactuator that operates according to the temperature of the cooling water. Provide one. Then, the movement stroke of the thermoactuator from the valve closing position of the second valve body at the cold start to the valve opening position of the second valve body is defined as the valve closing of the first valve body at the cold start. It is set short with respect to the movement stroke of the thermoactuator from the position until the first valve body reaches the valve opening position.

  With this configuration, in a situation where the first valve body and the second valve body move integrally by the operation of the thermoactuator, when the movement stroke reaches a predetermined amount, first, the second valve body is opened. Thereby, supply of the cooling water to the radiator flow path is started. Thereafter, when the moving stroke of the thermoactuator becomes further large, the first valve body is also opened. Thereby, supply of the cooling water to the cooling water flow path in the block is started, and an excessive increase in the temperature of the cylinder block is suppressed. As described above, the opening timing of the first valve body and the second valve body, that is, the cooling water temperature at which the first valve body opens and the cooling water at which the second valve body opens, depending on the moving stroke of the thermoactuator. The temperature can be made different. This makes it possible to switch the flow path in the cooling water circulation circuit while simplifying the configuration of the thermostat valve.

  The first valve body may have the following configuration. That is, when the temperature of the cooling water circulating through the cooling water circulation circuit is equal to or lower than the first predetermined temperature in the first valve body, A differential pressure valve that receives and opens the valve is provided.

  According to this configuration, even when the temperature of the cooling water circulating through the cooling water circulation circuit is equal to or lower than the first predetermined temperature and the supply of the cooling water to the block passage is blocked by the first valve body, When the discharge pressure of the pump becomes equal to or higher than the predetermined pressure, the supply of the cooling water to the block flow path is started by opening the differential pressure valve. For example, when the discharge pressure of the water pump becomes equal to or higher than a predetermined pressure during the warm-up operation of the internal combustion engine, the second valve body is not opened by opening the differential pressure valve. That is, the cooling water cooling operation by the radiator is not performed during the warm-up operation of the internal combustion engine. As a result, the coolant temperature can be raised within a short period after the start of the internal combustion engine, and friction loss at various locations in the internal combustion engine can be reduced, thereby contributing to an improvement in the fuel consumption rate.

  In addition, after the warm-up operation of the internal combustion engine is completed, in a situation where the temperature of the cylinder block may rise rapidly due to an increase in the rotational speed, the cylinder block can be cooled early by opening the differential pressure valve. The operation can be started. For this reason, an excessive increase in the temperature of the cylinder block can be suppressed.

  Specific configurations for setting the opening timing of the differential pressure valve include the following. That is, a state in which a biasing force in the valve closing direction is applied to the differential pressure valve of the first valve body by the first biasing means, and the temperature of the cooling water circulating in the cooling water circulation circuit is equal to or lower than a first predetermined temperature. When the discharge pressure of the water pump becomes equal to or higher than a predetermined pressure, the water pressure causes the differential pressure valve to open against the urging force of the first urging means, and the cooling water to the block flow path. Let the supply start. On the other hand, when the urging force in the valve closing direction is applied to the second valve body by the second urging means, and the temperature of the cooling water circulating in the cooling water circulation circuit is equal to or lower than the second predetermined temperature, The second valve body is closed by the urging force of the second urging means so that the supply of the cooling water to the radiator passage is shut off. The urging force of the first urging means is set smaller than the urging force of the second urging means.

  With this configuration, when the discharge pressure of the water pump becomes equal to or higher than a predetermined pressure regardless of whether the internal combustion engine is warming up or after the warming up is completed, the differential pressure valve is opened by the water pressure. By opening the differential pressure valve, as described above, when the internal combustion engine is warming up, the cooling water cooling operation by the radiator is prohibited, and when the internal combustion engine is after the warming up is complete, An excessive increase in the temperature of the cylinder block can be suppressed by starting the cooling operation of the cylinder block at an early stage.

  In the present invention, in the dual cooling device, the block channel is communicated with the outlet side of the in-head cooling water channel. Thereby, when supplying cooling water to the cooling water flow path in the block, by supplying the cooling water after passing through the cooling water flow path in the head, it is avoided that the cylinder block is rapidly cooled, and It is possible to prevent the flow rate of the cooling water flowing through the in-head cooling water flow path from decreasing.

It is a figure which shows typically the cooling water circulation circuit of the cooling device which concerns on 1st Embodiment. It is a cooling water circulation circuit diagram for demonstrating the cooling water circulation state during engine warming-up operation in 1st Embodiment. It is a cooling water circulation circuit diagram for demonstrating the cooling water circulation state after completion of engine warm-up operation in 1st Embodiment. It is a cooling water circulation circuit diagram for demonstrating the cooling water circulation state at the time of high water temperature in 1st Embodiment. FIG. 5A shows a conventional cooling water circulation circuit, FIG. 5A shows a cooling water circulation state during engine warm-up operation, FIG. 5B shows a cooling water circulation state after completion of engine warm-up operation, and FIG. It is a figure which shows the cooling water circulation state at the time of water temperature, respectively. It is a figure which shows typically the cooling water circulation circuit of the cooling device which concerns on 2nd Embodiment. It is a cooling water circulation circuit diagram for demonstrating the cooling water circulation state at the time of engine warm-up driving | running | working and the engine low to middle rotation in 2nd Embodiment. It is a cooling water circulation circuit diagram for demonstrating the cooling water circulation state at the time of engine high-speed rotation in engine warming-up in 2nd Embodiment. It is a cooling water circulation circuit diagram for demonstrating the cooling water circulation state after the engine warm-up operation completion in 2nd Embodiment and at the time of low to middle rotation of the engine. It is a cooling water circulation circuit diagram for demonstrating the cooling water circulation state after engine warm-up completion in 2nd Embodiment and at the time of engine high rotation. It is a cooling water circulation circuit diagram for demonstrating the cooling water circulation state at the time of high water temperature in 2nd Embodiment. FIG. 12A shows the pressure balance in the circuit during the engine warm-up operation in the second embodiment, FIG. 12A shows the pressure balance during the engine warm-up operation and during the low to medium rotation of the engine, and FIG. FIG. 12C is a diagram showing the pressure balance before the valve opening during the warm-up operation and at the time of high engine rotation, and FIG. 12C shows the pressure balance after the valve opening during the engine warm-up operation and at the time of high engine rotation. FIG. 13A shows a conventional cooling water circulation circuit, FIG. 13A shows a cooling water circulation state during engine warm-up operation and low to medium rotation, and FIG. 13B shows a cooling water circulation state during engine warm-up operation and high rotation. FIG. 13 (c) is a diagram showing a cooling water circulation state after completion of the engine warm-up operation, and FIG. 13 (d) is a diagram showing a cooling water circulation state at a high water temperature.

  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.

(First embodiment)
First, the first embodiment will be described.

-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. In FIG. 1, the thermostat placement location is shown enlarged.

  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.

  In addition, 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. . Specifically, the water pump P is configured such that a transmission belt is stretched between a water pump pulley provided on a drive shaft thereof and a crankshaft pulley attached to the crankshaft, whereby rotation of the crankshaft is performed. It is designed to operate under the driving force.

  A thermostat disposition space 1A is formed on the suction side of the water pump P in the cooling water circulation circuit 1 in the present embodiment, and a thermostat 4 is disposed in the thermostat disposition space 1A.

  In this thermostat installation space 1A, three inlets 4A, 4B, 4C and one outlet 4D are provided, respectively, and the thermostat is provided so as to face these inlets 4A, 4B, 4C and outlet 4D. 4 is arranged. The upstream side (suction side) of the water pump P is connected to the outlet 4D via the pump inflow passage 1a. The inlets 4A, 4B, 4C provided in the thermostat disposition space 1A are a radiator side inlet 4A, a heater side inlet 4B, and a block side inlet 4C. The thermostat 4 has a function of opening and closing the radiator side inlet 4A and the block side inlet 4C. Details will be described later.

  The downstream side (discharge side) of the water pump P is connected to the in-head cooling water channel 2a (the inlet side of the in-head cooling water channel 2a). That is, the total amount of the cooling water discharged from the water pump P once flows into the in-head cooling water flow path 2a.

  A take-out pipe 1b is connected to the downstream end (cooling water outlet side end) of the in-head cooling water flow path 2a. The take-out pipe 1b is branched into a first branch pipe 1c (cooling water supply path) and a second branch pipe 1d (cooling water supply path) in the first branch portion D1.

  The first branch pipe 1c is further branched into a radiator side supply pipe 5a and a heater side supply pipe 6a at the second branch portion D2.

  A radiator 5 is connected to the radiator-side supply pipe 5a, and an outlet side of the radiator 5 is connected to a radiator-side inlet 4A of the thermostat installation space 1A via a radiator-side recovery pipe 5b. Further, the heater 6 is disposed in the heater side supply pipe 6a, and the outlet side of the heater 6 is connected to the heater side inlet 4B of the thermostat installation space 1A via the heater side collection pipe 6b. . With this circuit configuration, the radiator side supply pipe 5a, the radiator 5, and the radiator side recovery pipe 5b constitute a radiator flow path 5A, while the heater side supply pipe 6a, the heater 6, and the heater side recovery pipe 6b provide a heater. A flow path 6A is configured. The radiator flow path 5 </ b> A functions so that cooling water that has passed from the water pump P through the in-head cooling water flow path 2 a flows into the water pump P via the radiator 5. The heater flow path 6A functions as a block bypass flow path for allowing the cooling water that has passed from the water pump P through the in-head cooling water flow path 2a to flow into the water pump P by bypassing the in-block cooling water flow path 3a.

  The radiator 5 performs heat exchange between the cooling water and the outside air (air blown by driving air or a cooling fan), and cools the cooling water by releasing the heat of the cooling water to the outside air. .

  The heater 6 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, during heating of the passenger compartment, the conditioned air flowing in the air duct is passed through the heater 6 and supplied as warm air to the passenger compartment. In other cases (for example, during cooling), the conditioned air bypasses the heater 6. ing.

  On the other hand, the downstream end of the second branch pipe 1d is connected to the in-block cooling water flow path 3a. The downstream end of the in-block cooling water flow path 3a is connected to the block side inlet 4C of the thermostat disposition space 1A via the block side recovery flow path 3b. With such a circuit configuration, a block flow path 3A is constituted by the second branch pipe 1d, the in-block cooling water flow path 3a, and the block-side recovery flow path 3b. The block flow path 3A functions so that the coolant from the water pump P that has passed through the in-head cooling water flow path 2a flows into the water pump P through the in-block cooling water flow path 3a.

  Thus, in the cooling water circulation circuit 1 in the present embodiment, the block flow path 3A, the radiator flow path 5A, and the heater flow path 6A are connected in parallel to each other by the branch portions D1 and D2. The flow paths 3A, 5A, 6A are connected in series to the in-head cooling water flow path 2a. That is, in any of the flow paths 3A, 5A, 6A, when the cooling water flows, the temperature rises due to heat exchange in the head cooling water flow path 2a after passing through the head cooling water flow path 2a. The cooling water flows later.

-Configuration of thermostat 4-
The thermostat (thermostat valve) 4 adjusts the temperature of the cooling water by switching the water path of the cooling water circulation circuit 1, and uses the thermal expansion of the thermowax enclosed therein, 43 has a mechanism that is opened and closed according to the cooling water temperature. The specific configuration of the thermostat 4 and the flow of cooling water accompanying the opening and closing of the valves 42 and 43 will be described below.

  The thermostat 4 mainly includes a thermo actuator 41, a radiator side valve (second valve body) 42, a block side valve (first valve body) 43, and a return spring 44.

  The thermoactuator 41 is a driving means for detecting the temperature change of the cooling water and opening / closing the valves 42 and 43. Specifically, the thermoactuator 41 includes a hollow cylindrical heat-sensitive cylinder (heat-sensitive part) 41a, and a push rod 41b is inserted into the heat-sensitive cylinder 41a. One end side (upper end side in the figure) of the push rod 41b in the longitudinal direction protrudes to the outside of the thermal cylinder 41a and is fixed to the inner wall of the flow path around the radiator side inlet 4A. A thermo wax (not shown) is filled in the internal space of the thermal cylinder 41a.

  The thermowax changes to a state of solidification shrinkage or a state of melt expansion depending on the temperature of the cooling water flowing around the thermal cylinder 41a, and generally known ones can be used. For this reason, in the situation where the temperature of the cooling water around the thermal cylinder 41a is relatively low, the thermowax contracts and the thermoactuator 41 (thermal cylinder 41a) moves to the upper position in the figure. On the other hand, in a situation where the cooling water temperature around the thermal cylinder 41a is relatively high, the thermowax expands and the thermoactuator 41 (thermal cylinder 41a) moves toward the lower position in the figure (FIG. 3). And the state shown in FIG. 4).

  The radiator side valve 42 is provided in the upper part of the thermal cylinder 41a. On the other hand, the block side valve 43 is attached to the lower part of the thermal cylinder 41a via a connecting shaft 41c. Thereby, each valve | bulb 42 and 43 moves up and down integrally in response to the up-and-down movement of the thermal cylinder 41a. Hereinafter, these valves 42 and 43 and their peripheral structures will be described.

  The radiator side valve 42 opens and closes the radiator side inflow port 4A. The radiator side valve 42 is continuous with the first disc portion 42a and the lower side of the first disc portion 42a. A second disk part 42b formed larger in diameter than the plate part 42a is integrally formed. The axial centers of these disc portions 42a and 42b coincide with the axial center of the push rod 41b.

  On the other hand, the inner diameter dimension of the radiator-side inlet 4A that is opened and closed by the radiator-side valve 42 is substantially equal to the outer diameter dimension of the first disc portion 42a, or from the outer diameter size of the first disc portion 42a. When the radiator side valve 42 is in a closed state (in the state shown in FIG. 1), the first disc portion 42a is fitted into the radiator side inlet 4A. Yes. Further, when the radiator side valve 42 is in a closed state, the upper surface of the second disc portion 42b comes into contact with the lower surface of the peripheral portion of the radiator side inlet 4A.

  The return spring 44 is disposed between the lower surface of the second disc portion 42b of the radiator side valve 42 and the upper surface of a flange portion 4Ca, which will be described later, forming the block side inlet 4C. The return spring 44 applies a biasing force in the valve closing direction (upward in FIG. 1) to the radiator side valve 42.

  For this reason, when the temperature of the cooling water around the thermal cylinder 41a is relatively low and the thermal cylinder 41a is moved to the upper position by the urging force of the return spring 44, the first disc portion 42a of the radiator side valve 42 is disposed in the radiator. The radiator side valve 42 is closed by fitting into the side inlet 4A and the upper surface of the second disc portion 42b abutting against the lower surface of the peripheral edge of the radiator side inlet 4A. On the other hand, in a state where the temperature of the cooling water around the thermal cylinder 41a is relatively high (for example, the cooling water temperature is 82 ° C. or higher) and the thermal cylinder 41a is moving downward against the urging force of the return spring 44, The first disc portion 42a of the radiator side valve 42 is detached from the radiator side inflow port 4A, and the upper surface of the second disc portion 42b is separated from the lower surface of the peripheral portion of the radiator side inflow port 4A, whereby the radiator side valve 42 is The valve is open (see the states of FIGS. 3 and 4).

  The block side valve 43 opens and closes the block side inlet 4C. The block side valve 43 is continuous to the disk-shaped first disk portion 43a and the lower side of the first disk portion 43a. The second disc portion 43b formed larger in diameter than the plate portion 43a is integrally formed. The axes of these disc portions 43a and 43b coincide with the axes of the push rod 41b and the connecting shaft 41c.

  On the other hand, the inner diameter dimension of the block-side inlet 4C that is opened and closed by the block-side valve 43 is substantially the same as the outer diameter dimension of the first disc portion 43a, or from the outer diameter size of the first disc portion 43a. When the block side valve 43 is in a closed state (in the state shown in FIG. 1), the first disc portion 43a is fitted into the block side inlet 4C. Yes. When the block side valve 43 is in a closed state, the upper surface of the second disc portion 43b is in contact with the lower surface of the peripheral edge of the block side inlet 4C.

  As a configuration of the peripheral portion of the block side inlet 4C, a flange portion 4Ca having a predetermined thickness dimension extends toward the block side valve 43, and is formed in a circular shape formed on the inner peripheral side of the flange portion 4Ca. Is formed as the block side inlet 4C.

  Therefore, when the temperature of the cooling water around the thermal cylinder 41a is relatively low and the thermal cylinder 41a is moved to the upper position by the biasing force of the return spring 44, the first disc portion 43a of the block side valve 43 is The block-side valve 43 is closed by fitting into the block-side inlet 4C and the upper surface of the second disc portion 43b abutting against the lower surface of the flange portion 4Ca. On the other hand, in the state where the cooling water temperature around the thermal cylinder 41a is relatively high (for example, the cooling water temperature is 90 ° C. or more) and the thermal cylinder 41a moves to the lower position against the urging force of the return spring 44, The first disc portion 43a of the block side valve 43 is detached from the block side inlet 4C, and the upper surface of the second disc portion 43b is separated from the lower surface of the flange portion 4Ca, so that the block side valve 43 is opened. It has a configuration (see the state of FIG. 4).

  The height dimension (plate thickness dimension) of the first disc portion 42 a of the radiator side valve 42 is set shorter than the height dimension (plate thickness dimension) of the first disc portion 43 a of the block side valve 43. . For example, it is set to about 1/2. In order to open the radiator-side inlet 4A from the state shown in FIG. 1 (the state where both the radiator-side valve 42 and the block-side valve 43 are closed), the first disc portion 42a of the radiator-side valve 42 is opened. It is necessary for the thermal cylinder 41a to move downward by the height dimension. On the other hand, in order to open the block-side inlet 4C from the state shown in FIG. 1, the thermal cylinder 41 a needs to move downward by the height dimension of the first disc portion 43 a of the block-side valve 43. As described above, the height dimension of the first disc portion 42a of the radiator side valve 42 is set to be shorter than the height dimension of the first disc portion 43a of the block side valve 43. First, when the upper surface position of the first disc portion 42a of the radiator side valve 42 reaches a position lower than the lower surface of the peripheral edge portion of the radiator side inflow port 4A, the radiator side inflow port 4A Open. Thereafter, when the thermal cylinder 41a further moves downward, the upper surface position of the first disk portion 43a of the block side valve 43 reaches a position lower than the lower surface of the flange portion 4Ca, so that the block side inlet 4C is opened. It is supposed to be. That is, when the coolant temperature rises to a predetermined temperature (second predetermined temperature; for example, 82 ° C.) during the warm-up operation of the engine E, the radiator-side inlet 4A is opened by opening the radiator-side valve 42, and the radiator flow When the cooling water flows through the passage 5A and the cooling water temperature further rises and reaches a predetermined temperature (first predetermined temperature; for example, 90 ° C.), the block side inlet 4C is opened by opening the block side valve 43. The cooling water also flows through the block flow path 3A. That is, the radiator side valve 42 has a function of blocking the supply of the cooling water to the radiator flow path 5A when the temperature of the cooling water circulating through the cooling water circulation circuit 1 is equal to or lower than the second predetermined temperature. Yes. Further, the block side valve 43 has a function of blocking the supply of the cooling water to the block flow path 3A when the temperature of the cooling water circulating in the cooling water circulation circuit 1 is not more than the first predetermined temperature. Yes.

−Cooling water circulation operation−
Next, the cooling water circulation operation in the cooling water circulation circuit 1 configured as described above will be described. As a form of this cooling water circulation operation, there are “during engine warm-up operation”, “after completion of engine warm-up operation”, and “during high water temperature”. 2 shows a cooling water circulation state during engine warm-up operation, FIG. 3 shows a cooling water circulation state after completion of the engine warm-up operation, and FIG. 4 shows a cooling water circulation state at a high water temperature. In these drawings, the flow path in which the cooling water flows and the flow direction thereof are indicated by solid arrows, and the flow path in which the cooling water does not flow is indicated by broken lines.

(During engine warm-up operation)
When the engine E is cold started, since the coolant temperature is low, the radiator side valve 42 and the block side valve 43 are both closed as shown in FIG. That is, the downstream end of the radiator flow path 5A and the downstream end of the block flow path 3A are both closed (blocked).

  In this case, the cooling water discharged from the water pump P passes through the in-head cooling water flow path 2a, the take-out pipe 1b, the first branch portion D1, the first branch pipe 1c, the heater flow path 6A, and the heater side inlet 4B. A circulation operation is performed in which the air flows into the arrangement space 1A and is sucked into the water pump P from the thermostat arrangement space 1A through the outlet 4D and the pump inlet passage 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. As a result, friction loss at various locations within the engine E can be reduced within a short period of time after the engine is started, which can contribute to an improvement in the fuel consumption rate.

  As the engine warm-up operation continues, the coolant temperature rises. As the cooling water temperature rises, the thermowax expands, and the thermoactuator 41 moves toward the lower position in the figure.

(After completion of engine warm-up operation)
When the engine warm-up operation is continued and the coolant temperature rises and reaches a predetermined temperature (for example, 82 ° C.), the operation is switched to the coolant circulation operation after the engine warm-up operation is completed (see FIG. 3). In the cooling water circulation operation after completion of the engine warm-up operation, the thermal cylinder 41a moves downward as the cooling water temperature rises, the radiator side valve 42 is opened, and the radiator side inlet 4A is opened. On the other hand, the block side valve 43 is still closed and the block side inlet 4C is closed.

  In this case, the cooling water discharged from the water pump P reaches the second branch portion D2 via the in-head cooling water flow path 2a, the take-out pipe 1b, the first branch portion D1, and the first branch tube 1c. The cooling water is diverted in the second branch portion D2, and one of them flows into the thermostat disposition space 1A via the heater flow path 6A and the heater side inlet 4B. The other flows into the thermostat disposition space 1A through the radiator flow path 5A and the radiator side inlet 4A. The cooling water that has flowed into the thermostat-arranged space 1A performs a circulation operation in which it is sucked into the water pump P through the outlet 4D and the pump inlet passage 1a. By such a circulating operation of the cooling water, the cooling water flowing through the radiator flow path 5A is cooled by the radiator 5, and a part of the heat recovered from the cylinder head 2 is released into the atmosphere, whereby this cylinder The temperature of the head 2 can be maintained appropriately. Such an operation is continued while the cooling water temperature is lower than a predetermined temperature (for example, 90 ° C.) (for example, when the engine E is in a low to medium load operation or in a low to medium rotation).

(High water temperature)
When the cooling water temperature reaches a predetermined temperature (for example, 90 ° C.) due to an increase in the load on the engine E or an increase in the rotation speed of the engine E, the operation is switched to the cooling water circulation operation at a high water temperature (see FIG. 4). Change. In the cooling water circulation operation at this high water temperature, as the cooling water temperature further rises, the thermal cylinder 41a moves further downward, the opening of the radiator side valve 42 increases, and the block side valve 43 also opens. Thus, the block side inlet 4C is opened.

  In this case, the cooling water discharged from the water pump P reaches the first branch portion D1 via the in-head cooling water flow path 2a and the extraction pipe 1b. The cooling water is diverted in the first branch portion D1, one of which flows into the first branch pipe 1c and the other into the second branch pipe 1d.

  The cooling water that has flowed to the first branch pipe 1c reaches the second branch portion D2, and is diverted in the second branch portion D2, and one of the coolant passes through the heater flow path 6A and the heater side inlet 4B, and the thermostat installation space. Flow into 1A. The other flows into the thermostat disposition space 1A through the radiator flow path 5A and the radiator side inlet 4A.

  On the other hand, the cooling water that has flowed into the second branch pipe 1d flows into the thermostat-arranged space 1A via the in-block cooling water flow path 3a and the block-side recovery flow path 3b.

  The cooling water that has flowed into the thermostat-arranged space 1A performs a circulation operation in which it is sucked into the water pump P through the outlet 4D and the pump inlet passage 1a. The cylinder block 3 is cooled by such a circulating operation of the cooling water.

  The opening degree of the radiator side valve 42 and the opening degree of the block side valve 43 increase as the cooling water temperature increases. That is, since the pressure loss with respect to the cooling water flow in each of the valves 42 and 43 becomes smaller, the discharge amount of the water pump P increases, thereby increasing the flow rate of the cooling water in each of the flow paths 3A, 5A, and 6A. Will go. As a result, the cooling capacity for the cylinder head 2 and the cylinder block 3 increases.

  In any of the above-described cooling water circulation operations, the cooling water flows through the heater flow path 6A, and heat exchange with the vehicle interior air is performed in the heater 6 as necessary.

  As described above, in the present embodiment, when the cooling water temperature becomes high and reaches the above “high water temperature”, the cooling water whose temperature has increased due to passing through the in-head cooling water flow path 2 a It flows into the cooling water flow path 3a.

  Conventionally, when the cooling water supply to the cooling water flow path in the block is started, the low temperature cooling water cooled by the radiator is supplied to the cylinder block at a low temperature. Wall temperature) rapidly decreases, the friction loss fluctuates, and the amount of thermal deformation of the cylinder block becomes uneven. There was a possibility that the reliability deteriorated. Further, conventionally, since the cooling water flow channel in the head and the cooling water flow channel in the block are in parallel with each other, the supply of the cooling water to the cooling water flow channel in the block is started, and accordingly, As a result, the amount of cooling water supplied will decrease, and the cooling capacity for the cylinder head may not be fully exhibited. This will be specifically described below.

  FIG. 5 shows a cooling water circulation circuit (using two thermostats) that is a conventional two-system cooling system. 5A shows a cooling water circulation state during engine warm-up operation, FIG. 5B shows a cooling water circulation state after completion of the engine warm-up operation, and FIG. 5C shows a cooling water circulation state at a high water temperature. The flow path in which the cooling water flows and the flow direction thereof are indicated by solid arrows, and the flow path in which the cooling water does not flow is indicated by broken lines. In FIG. 5, symbol a is the engine, symbol b is the head cooling water channel, symbol c is the block cooling water channel, symbol d is the water pump, symbol e is the radiator, symbols f and g are thermostats, and symbol h is It is a bypass flow path. In this conventional cooling water circulation circuit, the cooling water temperature becomes higher from the cooling water circulation state after completion of the engine warm-up operation shown in FIG. 5 (b), and the cooling water circulation state at the high water temperature shown in FIG. 5 (c). When switching to, the low-temperature cooling water cooled by the radiator e is supplied to the in-block cooling water flow path c via the thermostats f and g and the water pump d. There is a possibility that the fuel consumption rate is deteriorated and the reliability of the engine is deteriorated rapidly, and the supply amount of the cooling water to the cooling water flow path b in the head is reduced. There was a possibility that the cooling capacity for the head could not be fully exhibited.

  On the other hand, according to the present embodiment, the cooling water whose temperature has increased due to passing through the in-head cooling water flow path 2a flows into the in-block cooling water flow path 3a. Thus, it is possible to avoid a situation where the engine E decreases, and to improve the fuel consumption rate and to ensure the reliability of the engine E by preventing thermal distortion. In addition, since the amount of cooling water supplied to the in-head cooling water flow path 2a does not decrease, the cooling capacity for the cylinder head 2 is sufficient even after the operation of supplying cooling water to the in-block cooling water flow path 3a is started. In particular, reliability at a high water temperature can be sufficiently secured.

  Further, in the present embodiment, the bypass flow path h (dedicated flow path for bypassing the radiator e during the warm-up operation; see FIG. 5) that is necessary in the conventional cooling water circulation circuit is eliminated, or Since it can be used as the block flow path 3A, the manufacturing cost of the cooling water circulation circuit 1 can be reduced and the weight thereof can be reduced.

(Second Embodiment)
Next, a second embodiment will be described. In the present embodiment, the configuration of the block side valve 43 is different from that of the first embodiment. Accordingly, differences from the first embodiment will be mainly described here.

  FIG. 6 is a diagram schematically showing the cooling water circulation circuit 1 of the cooling device according to the present embodiment. Also in this FIG. 6, the thermostat arrangement | positioning location is expanded and shown. In FIG. 6, the same components as those in the first embodiment are denoted by the same reference numerals. In the following, description of this same component will be omitted.

  The block side valve 43 according to this embodiment includes a main valve 46 and a relief valve 47.

  The main valve 46 has the same configuration and function as the block side valve 43 in the first embodiment described above. That is, the main valve 46 opens and closes the block-side inlet 4C, and is continuous with the first disk-shaped disk part 46a and the lower side of the first disk part 46a. A second disk part 46b formed larger in diameter than the one disk part 46a is integrally formed. The axial centers of the disk portions 46a and 46b coincide with the axial centers of the push rod 41b and the connecting shaft 41c. Further, a through hole 46c penetrating in the vertical direction is formed at the center of these disk portions 46a and 46b. The internal space of the through hole 46 c is used as a storage space for the relief valve 47. Further, the main valve 46 is supported by the lower end portion of the connecting shaft 41c. Specifically, the connecting shaft 41c extends downward in the internal space of the through hole 46c of the main valve 46, and a plurality of support plates 41d extending in the horizontal direction from the lower end of the connecting shaft 41c abut on the lower end of the main valve 46. Thus, the main valve 46 is supported in a state in which the main valve 46 is prevented from falling. The support plate 41d allows the cooling water to flow from the block-side recovery channel 3b into the through hole 46c and allows the cooling water pressure to act on the lower surface of the relief valve 47 in the circumferential direction. It is arranged intermittently.

  The operation of the main valve 46 is the same as the operation of the block side valve 43 in the first embodiment. That is, when the temperature of the cooling water around the thermal cylinder 41a is relatively low and the thermal cylinder 41a is moved to the upper position, the first disk portion 46a of the main valve 46 is fitted into the block-side inlet 4C, The main valve 46 is closed by the upper surface of the second disk portion 46b coming into contact with the lower surface of the flange portion 4Ca. On the other hand, when the temperature of the cooling water around the thermal cylinder 41a is relatively high and the thermal cylinder 41a is moving to the lower position, the first disk portion 46a of the main valve 46 is detached from the block side inlet 4C, The main valve 46 is configured to be opened when the upper surface of the second disk portion 46b is separated from the lower surface of the flange portion 4Ca (see the state of FIG. 11).

  On the other hand, the relief valve 47 opens and closes the through hole 46c of the main valve 46. The relief valve 47 is continuous with the first disc-shaped disc portion 47a and the lower side of the first disc portion 47a. A second disk part 47b formed with a smaller diameter than the first disk part 47a is integrally formed. The axes of these disc portions 47a and 47b coincide with the axes of the push rod 41b and the connecting shaft 41c.

  The outer diameter of the second disc portion 47 b of the relief valve 47 is smaller than the inner diameter of the through hole 46 c of the main valve 46. Further, the outer diameter of the first disk portion 47a of the relief valve 47 is larger than the inner diameter of the through hole 46c of the main valve 46 and the inner diameter of the block side inlet 4C (outside the first disk portion 46a). It is smaller than the diameter dimension). A return spring 48 (first urging means) is disposed between the upper surface of the first disc portion 47a of the relief valve 47 and the lower surface of the thermal cylinder 41a. A biasing force in the valve closing direction (downward in FIG. 6) is applied to the valve 47. The urging force of the return spring 48 is set smaller than the urging force of the return spring (second urging means) 44 that urges the radiator side valve 42. Specifically, the urging force of the return springs 44 and 48 is such that when the water pressure in the cooling water circulation circuit 1 rises, the relief valve 47 is opened before the radiator side valve 42 is opened by the water pressure (return). The relief valve 47 is separated from the main valve 46 against the biasing force of the spring 48).

  Other configurations of the thermostat 4 and the configuration of the coolant circulation circuit 1 are the same as those of the first embodiment described above.

−Cooling water circulation operation−
Next, the cooling water circulation operation in this embodiment will be described. The cooling water circulation mode is as follows: “While engine warm-up / low to medium rotation”, “While engine warm-up / high rotation”, “After engine warm-up is completed / low to medium rotation”, There are "after engine warm-up operation and high rotation" and "high water temperature". FIG. 7 shows a cooling water circulation state during engine warm-up / low to medium rotation, FIG. 8 shows a cooling water circulation state during engine warm-up / high rotation, and FIG. 9 shows engine warm-up. FIG. 10 shows the cooling water circulation state after the completion of operation / low to medium rotation, FIG. 10 shows the cooling water circulation state after completion of the engine warm-up operation / high rotation, and FIG. 11 shows the cooling water circulation state at high water temperature. Is shown. In these drawings, the flow path in which the cooling water flows and the flow direction thereof are indicated by solid arrows, and the flow path in which the cooling water does not flow is indicated by broken lines.

(During engine warm-up operation, low to medium rotation)
When the engine is warming up and the engine speed is relatively low (low to medium speed; about 4000 rpm or less), the cooling water temperature is low, and therefore, as shown in FIG. Both the main valves 46 of the block side valve 43 are closed. Further, since the cooling water pressure (discharge pressure of the water pump P) in the cooling water circulation circuit 1 is low, the pressure acting on the lower surface of the relief valve 47 of the block side valve 43 is low, and the relief valve 47 is applied by the urging force of the return spring 48. Is also closed. That is, the downstream end of the radiator flow path 5A and the downstream end of the block flow path 3A are both closed (blocked).

  In this case, the cooling water discharged from the water pump P passes through the in-head cooling water flow path 2a, the take-out pipe 1b, the first branch portion D1, the first branch pipe 1c, the heater flow path 6A, and the heater side inlet 4B. A circulation operation is performed in which the air flows into the arrangement space 1A and is sucked into the water pump P from the thermostat arrangement space 1A through the outlet 4D and the pump inlet passage 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. As a result, friction loss at various locations in the engine can be reduced within a short period of time after the engine is started, which can contribute to an improvement in the fuel consumption rate.

(While the engine is warming up or at high speed)
During the engine warm-up operation described above, from low to medium rotation, the vehicle started before the warm-up operation was completed, and the amount of depression of the accelerator pedal increased. (Time: 4000 rpm or more), the discharge pressure increases as the rotation speed of the water pump P increases, and the pressure reaches the block side inlet 4C via the block flow path 3A. Then, when the water pressure becomes larger than the urging force of the return spring 48 urging the relief valve 47, the relief valve 47 moves upward and separates from the main valve 46 as shown in FIG. The through hole 46c of the main valve 46 is opened. Thereby, 3 A of block flow paths and the thermostat arrangement | positioning space 1A communicate. By such opening operation of the relief valve 47, the cooling water flows from the block flow path 3A to the pump inflow path 1a via the thermostat installation space 1A.

  That is, the cooling effect of the cylinder block 3 is exhibited by the cooling water flowing through the in-block cooling water flow path 3a. That is, in a situation where the engine speed increases and the temperature of the cylinder block 3 may rise rapidly, the cooling operation of the cylinder block 3 is started from the stage before the main valve 46 is opened by the operation of the thermoactuator 41. Therefore, an excessive increase in the temperature of the cylinder block 3 can be suppressed. Further, since the urging force of the return spring 48 that urges the relief valve 47 is smaller than the urging force of the return spring 44 that urges the radiator side valve 42, the engine speed is high. When the water pressure increases, the relief valve 47 is opened by the water pressure, and the cooling water flows through the block flow path 3A, so that the water pressure acting on the radiator side valve 42 is reduced. The radiator side valve 42 is never opened. That is, the radiator-side valve 42 is not opened during the engine warm-up operation, and the cooling water cooling operation by the radiator 5 is prohibited, and the cooling water temperature is reduced within a short period after the engine is started. As a result, the friction loss at various locations in the engine can be reduced, thereby contributing to the improvement of the fuel consumption rate.

(After completion of engine warm-up operation, during low to medium rotation)
When the engine warm-up operation continues and the coolant temperature rises and reaches a predetermined temperature (for example, 82 ° C.), the operation is switched to the coolant circulation operation after the engine warm-up operation is completed. When the engine speed is relatively low after completion of the engine warm-up operation (low to medium rotation; about 4000 rpm or less), as shown in FIG. Moving downward, the radiator-side valve 42 is opened, and the radiator-side inlet 4A is opened. On the other hand, the main valve 46 of the block side valve 43 is still closed. Further, since the discharge pressure of the water pump P is low, the relief valve 47 of the block side valve 43 is also closed, and as a result, the block side inlet 4C is closed.

  In this case, the cooling water discharged from the water pump P reaches the second branch portion D2 via the in-head cooling water flow path 2a, the take-out pipe 1b, the first branch portion D1, and the first branch tube 1c. The cooling water is diverted in the second branch portion D2, and one of them flows into the thermostat disposition space 1A via the heater flow path 6A and the heater side inlet 4B. The other flows into the thermostat disposition space 1A through the radiator flow path 5A and the radiator side inlet 4A. The cooling water that has flowed into the thermostat-arranged space 1A performs a circulation operation in which it is sucked into the water pump P through the outlet 4D and the pump inlet passage 1a. By such a circulating operation of the cooling water, the cooling water flowing through the radiator flow path 5A is cooled by the radiator 5, and a part of the heat recovered from the cylinder head 2 is released into the atmosphere, whereby this cylinder The temperature of the head 2 can be maintained appropriately. Such an operation is continued while the cooling water temperature is lower than a predetermined temperature (for example, 90 ° C.).

(After completion of engine warm-up operation / high rotation)
On the other hand, after the engine warm-up operation is completed, when the engine speed is relatively high (for example, at a high speed; 4000 rpm or more) due to an increase in the amount of depression of the accelerator pedal, the speed of the water pump P is reduced. As the pressure rises, the discharge pressure rises, and the pressure reaches the block-side inlet 4C via the block flow path 3A. When this water pressure becomes larger than the urging force of the return spring 48 that urges the relief valve 47, the relief valve 47 moves upward and separates from the main valve 46 as shown in FIG. The through hole 46c of the main valve 46 is opened. Thereby, 3 A of block flow paths and the thermostat arrangement | positioning space 1A communicate. By such opening operation of the relief valve 47, the cooling water flows from the block flow path 3A to the pump inflow path 1a via the thermostat installation space 1A.

  In this case, the cooling water discharged from the water pump P reaches the first branch portion D1 via the in-head cooling water flow path 2a and the extraction pipe 1b. The cooling water is diverted in the first branch portion D1, one of which flows into the first branch pipe 1c and the other into the second branch pipe 1d.

  The cooling water that has flowed to the first branch pipe 1c reaches the second branch portion D2, and is diverted in the second branch portion D2, and one of the coolant passes through the heater flow path 6A and the heater side inlet 4B, and the thermostat installation space. Flow into 1A. The other flows into the thermostat disposition space 1A through the radiator flow path 5A and the radiator side inlet 4A.

  On the other hand, the cooling water that has flowed into the second branch pipe 1d flows into the thermostat-arranged space 1A through the in-block cooling water channel 3a and the block-side recovery channel 3b.

  The cooling water that has flowed into the thermostat-arranged space 1A performs a circulation operation in which it is sucked into the water pump P through the outlet 4D and the pump inlet passage 1a. The cylinder block 3 is cooled by such a circulating operation of the cooling water.

  Thus, the cooling effect of the cylinder block 3 is exhibited by the cooling water flowing through the in-block cooling water flow path 3a. That is, in a situation where the engine speed increases and the temperature of the cylinder block 3 may rise rapidly, the relief valve 47 is opened from the stage before the main valve 46 is opened by the operation of the thermoactuator 41. The cooling operation of the cylinder block 3 can be started, and an excessive increase in the temperature of the cylinder block 3 can be suppressed.

(High water temperature)
When the cooling water temperature reaches a predetermined temperature (for example, 90 ° C.) due to an increase in the load on the engine E or an increase in the rotational speed of the engine E, the operation is switched to the cooling water circulation operation at a high water temperature (see FIG. 11). Change. In the cooling water circulation operation at this high water temperature, as the cooling water temperature further increases, the thermal cylinder 41a moves further downward, the opening of the radiator side valve 42 increases, and the main valve 46 of the block side valve 43 increases. Is also opened, and the block side inlet 4C is opened. As the main valve 46 is opened, there is no pressure difference between the upper surface and the lower surface of the relief valve 47 (front / rear differential pressure for opening the relief valve 47). The urging force moves downward in the figure to close the through hole 46c of the main valve 46.

  In this case, the cooling water discharged from the water pump P reaches the first branch portion D1 via the in-head cooling water flow path 2a and the extraction pipe 1b. The cooling water is diverted in the first branch portion D1, one of which flows into the first branch pipe 1c and the other into the second branch pipe 1d.

  The cooling water that has flowed to the first branch pipe 1c reaches the second branch portion D2, and is diverted in the second branch portion D2, and one of the coolant passes through the heater flow path 6A and the heater side inlet 4B, and the thermostat installation space. Flow into 1A. The other flows into the thermostat disposition space 1A through the radiator flow path 5A and the radiator side inlet 4A.

  On the other hand, the cooling water that has flowed into the second branch pipe 1d flows into the thermostat-arranged space 1A through the in-block cooling water channel 3a and the block-side recovery channel 3b. That is, the temperature of the cooling water flowing into the in-block cooling water flow path 3a is increased by heat exchange in the in-head cooling water flow path 2a.

  The cooling water that has flowed into the thermostat-arranged space 1A performs a circulation operation in which it is sucked into the water pump P through the outlet 4D and the pump inlet passage 1a. The cylinder block 3 is cooled by such a circulating operation of the cooling water.

  The opening degree of the radiator side valve 42 and the opening degree of the main valve 46 of the block side valve 43 increase as the coolant temperature increases. That is, since the pressure loss with respect to the cooling water flow in each of the valves 42 and 46 is reduced, the discharge amount of the water pump P is increased, thereby increasing the flow rate of the cooling water in each of the flow paths 3A, 5A, and 6A. Will go. As a result, the cooling capacity for the cylinder head 2 and the cylinder block 3 increases.

  In any of the above-described cooling water circulation operations, the cooling water flows through the heater flow path 6A, and heat exchange with the vehicle interior air is performed in the heater 6 as necessary.

  FIG. 12 shows the pressure balance in the circuit during the engine warm-up operation in the present embodiment. Specifically, FIG. 12A shows the pressure balance during the engine warm-up operation and when the engine is low to medium rotation, and FIG. 12B shows the engine warm-up operation and before the valve is opened during the high engine rotation. FIG. 12C shows the pressure balance after the valve is opened during the engine warm-up operation and at a high engine speed (after the relief valve 47 is opened). ing. In the following description, the valve front-rear differential pressure at which the radiator side valve 42 opens is P1, and the valve front-rear differential pressure at which the relief valve 47 opens is P2 (P1> P2).

  During engine warm-up operation and during low to medium rotation of engine E, as shown in FIG. 12A, the differential pressure across the radiator side valve 42 and the differential pressure across the block side valve 43 (relief valve 47) are: Both coincide with the differential pressure across the heater 6 (corresponding to the pressure loss at the heater 6). In this case, the front-rear differential pressure of the radiator side valve 42 is P1 or less, and the front-rear differential pressure of the block side valve 43 is P2 or less. Therefore, neither of the valves 42, 47 is opened, and the cooling shown in FIG. It becomes a water circulation state.

  Further, when the engine is warming up and before the valve is opened at the time of high engine rotation (before the relief valve 47 is opened), the discharge pressure of the water pump P increases as shown in FIG. Accordingly, both the pressure loss in the head cooling water flow path 2a (cylinder head pressure loss) and the pressure loss in the heater 6 are increased. In addition, both the front-rear differential pressure of the radiator side valve 42 and the front-rear differential pressure of the block side valve 43 (relief valve 47) both increase, but the front-rear differential pressure of the radiator side valve 42 is P1 or less. Since the pressure is P2 or less, none of the valves 42 and 47 is opened in this case.

  Then, when the differential pressure across the block side valve 43 (relief valve 47) reaches P2, the relief valve 47 is opened and the cooling water circulation state shown in FIG. 8 is established. In this case, as shown in FIG. 12C, in the cooling water flowing through the block flow path 3A, the pressure loss in the in-block cooling water flow path 3a and the pressure loss in the relief valve 47 are generated. Become.

  As described above, also in the present embodiment, when the cooling water temperature becomes high and the above-mentioned “high water temperature” is reached, the in-head cooling water flow path 2a is set in the same manner as in the first embodiment. The cooling water whose temperature has risen due to the passage flows into the in-block cooling water flow path 3a. For this reason, the situation where the temperature of the cylinder block 3 rapidly decreases can be avoided, and the reliability of the engine E can be secured by improving the fuel consumption rate and preventing thermal distortion. In addition, since the amount of cooling water supplied to the in-head cooling water flow path 2a does not decrease, the cooling capacity for the cylinder head 2 is sufficient even after the operation of supplying cooling water to the in-block cooling water flow path 3a is started. In particular, reliability at a high water temperature can be sufficiently secured.

  Further, in this embodiment, the relief valve 47 is provided in the block side valve 43, and the relief valve 47 is opened when the discharge pressure of the water pump P rises to a predetermined pressure. For this reason, during the warm-up operation of the engine E, the relief valve 47 is opened as the water pressure increases, and the radiator side valve 42 is not opened. That is, the radiator-side valve 42 is not opened during the warm-up operation of the engine E, and the cooling water cooling operation by the radiator 5 is prohibited. As a result, the coolant temperature can be raised within a short period after the engine is started, and friction loss at various locations in the engine can be reduced, thereby contributing to an improvement in fuel consumption rate.

  Further, after the warm-up operation of the engine E is completed, in a situation where the temperature of the cylinder block 3 may rise rapidly due to an increase in the engine speed, before the main valve 46 is opened by the operation of the thermoactuator 41. From the stage, the cooling operation of the cylinder block 3 by opening the relief valve 47 can be started. For this reason, an excessive increase in the temperature of the cylinder block 3 can be suppressed.

  In the conventional dual cooling system, the engine speed is relatively high after the engine warm-up operation is completed, for example, the engine speed is relatively high and the cylinder block needs to be cooled. There is a possibility that the temperature of the flowing cooling water is low, the switching operation of the thermostat is delayed, and the timing for starting the cooling operation of the cylinder block is also delayed. Also, when the discharge pressure of the water pump rises as the engine speed increases during engine warm-up operation, the water pressure opens the valve on the radiator side of the thermostat, and the engine is warming up. Nevertheless, there is a possibility that the cooling operation of the cooling water by the radiator may be performed. This will be specifically described below.

  FIG. 13 shows a cooling water circulation circuit (using two thermostats) that is a conventional two-system cooling system. FIG. 13A shows the cooling water circulation state during engine warm-up / low to medium rotation, and FIG. 13B shows the cooling water circulation state during engine warm-up / high rotation. ) Shows the cooling water circulation state after completion of the engine warm-up operation, FIG. 13 (d) shows the cooling water circulation state at the time of high water temperature, the flow path through which the cooling water flows and the flow direction thereof are indicated by solid arrows, A flow path through which the cooling water does not flow is indicated by a broken line. In addition, each code | symbol in a figure is the same as that of the said FIG.

  In this conventional cooling water circulation circuit, when the engine speed increases from the cooling water circulation state of the engine warm-up / low to medium rotation shown in FIG. 13 (a), the discharge pressure of the water pump d increases, The water pressure opens the radiator-side valve of the thermostat f, and as shown in FIG. 13B, the cooling operation of the cooling water by the radiator e may be performed despite the warm-up operation. There was sex. Further, even when the engine speed increases from the cooling water circulation state after completion of the engine warm-up operation shown in FIG. 13C and the cylinder block needs to be cooled, the thermostat g switching operation (the expansion of the thermowax) The switching operation due to the above) is delayed, the start timing of the cooling operation of the cylinder block is delayed, and there is a possibility that the temperature of the cylinder block is excessively increased.

  On the other hand, in the present embodiment, as described above, when the discharge pressure of the water pump P rises to a predetermined pressure, the relief valve 47 is opened so that the cooling water flows into the in-block cooling water flow path 3a. During the warm-up operation, the relief valve 47 is opened by the water pressure so that the radiator side valve 42 is not opened, and the cooling operation of the cooling water by the radiator 5 is prohibited. The coolant temperature can be raised within a short period after the engine is started. Further, after the warm-up is completed, the cooling effect of the cylinder block 3 can be exhibited early.

-Other embodiments-
Each embodiment described above demonstrated the case where this invention was applied to the cooling device of the engine E for motor vehicles. The present invention is not limited to this, and can also be applied to a cooling device for an engine used other than an automobile.

  In each of the above embodiments, a mechanical pump that operates by receiving the rotational driving force of the crankshaft is employed as the water pump P. The present invention is not limited to this, and can be applied to a cooling device including an electric water pump driven by an electric motor.

  Further, in each of the above embodiments, after the warm-up operation of the engine E is completed, the cooling water that has flowed through the in-head cooling water flow path 2a is supplied to the heater flow path 6A and the radiator flow path 5A, respectively. That is, the cooling water is supplied to the block channel 3A only when the cooling water is at a high temperature. The present invention is not limited to this. After the warm-up operation is completed, the cooling water that has flowed through the in-head cooling water flow path 2a is supplied to the heater flow path 6A, the radiator flow path 5A, and the block flow path 3A, respectively. It can also be applied to a water circulation circuit.

  Further, in each of the above embodiments, the flow path through which the cooling water circulates during the warm-up operation of the engine E is the heater flow path 6A. The present invention is not limited to this, and can also be applied to a cooling water circulation circuit in which cooling water is circulated through a flow path provided with an EGR (Exhaust Gas Recirculation) cooler. In addition, during the warm-up operation of the engine E, the cooling water may be circulated through a flow path that does not include devices such as a heater and an EGR cooler.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a cooling system for optimizing the temperature of a cylinder block and a cylinder head when starting supply of cooling water to a cooling water flow path in the block, with respect to a dual cooling system provided with one thermostat.

1 Cooling Water Circulation Circuit 1c First Branch Pipe (Cooling Water Supply Path)
1d Second branch pipe (cooling water supply path)
2 Cylinder head 2a In-head cooling water flow path 3 Cylinder block 3a In-block cooling water flow path 3A Block flow path 4 Thermostat (thermostat valve)
41 Thermoactuator 42 Radiator side valve (second valve body)
43 Block side valve (1st valve body)
44 Return spring (second biasing means)
46 Main valve 47 Relief valve 48 Return spring (first biasing means)
5 Radiator 5A Radiator flow path 6A Heater flow path (Block bypass flow path)
D1 1st branch part (branch part)
E engine (internal combustion engine)
P Water pump

Claims (5)

In a cooling device for an internal combustion engine comprising a cooling water circulation circuit having an in-head cooling water passage provided in a cylinder head of the internal combustion engine and an in-block cooling water passage provided in a cylinder block,
A water pump for discharging cooling water toward the inlet side of the cooling water flow path in the head;
A block bypass passage for allowing the cooling water from the water pump to pass through the in-head cooling water passage to bypass the in-block cooling water passage and flow into the water pump;
A radiator flow path for allowing cooling water from the water pump to pass through the in-head cooling water flow path to the water pump via the radiator;
A block flow path for allowing cooling water from the water pump to pass through the cooling water flow path in the head to flow into the water pump via the cooling water flow path in the block;
When the temperature of the cooling water circulating through the cooling water circulation circuit is equal to or lower than a first predetermined temperature, the first valve body for cutting off the supply of the cooling water to the block flow path, and the cooling circulating through the cooling water circulation circuit A thermostat valve having a second valve body that shuts off the supply of cooling water to the radiator flow path when the temperature of the water is equal to or lower than a second predetermined temperature;
On the outlet side of the in-head cooling water flow path, there is provided a branching portion that branches the cooling water supply path to the block bypass flow path and the radiator flow path and the cooling water supply path to the block flow path. A cooling device for an internal combustion engine. The cooling apparatus for an internal combustion engine according to claim 1,
The cooling apparatus for an internal combustion engine, wherein the first predetermined temperature is set higher than the second predetermined temperature. The cooling apparatus for an internal combustion engine according to claim 1 or 2,
The first valve body and the second valve body of the thermostat valve are integrated with the thermoactuator so as to switch between the closed state and the open state according to the moving stroke of the thermoactuator that operates according to the temperature of the cooling water. Provided,
The movement stroke of the thermoactuator from the closed position of the second valve body at the cold start to the open position of the second valve body is from the closed position of the first valve body at the cold start. A cooling apparatus for an internal combustion engine, characterized in that the first valve body is set to be short with respect to a moving stroke of a thermoactuator until the first valve body reaches a valve opening position. The cooling device for an internal combustion engine according to claim 1, 2, or 3,
In the state where the temperature of the cooling water circulating in the cooling water circulation circuit is equal to or lower than the first predetermined temperature, the first valve body is supplied with the pressure when the discharge pressure of the water pump exceeds the predetermined pressure. A cooling apparatus for an internal combustion engine, characterized by being provided with a differential pressure valve that receives and opens the valve. The cooling apparatus for an internal combustion engine according to claim 4,
A biasing force in the valve closing direction is applied to the differential pressure valve of the first valve body by the first biasing means, and the temperature of the cooling water circulating in the cooling water circulation circuit is equal to or lower than the first predetermined temperature. In this state, when the discharge pressure of the water pump becomes equal to or higher than a predetermined pressure, the water pressure causes the differential pressure valve to open against the urging force of the first urging means, and the cooling water to the block flow path While the supply of
A biasing force in the valve closing direction is applied to the second valve body by the second biasing means, and when the temperature of the cooling water circulating in the cooling water circulation circuit is equal to or lower than a second predetermined temperature, The second valve body is closed by the urging force of the second urging means, and the supply of cooling water to the radiator flow path is shut off,
The cooling apparatus for an internal combustion engine, wherein an urging force of the first urging means is set smaller than an urging force of the second urging means.

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