Engine cooling system

Abstract

To quickly warm up an engine with improved quietness and suppressed variations in temperature.SOLUTION: An engine cooling system 1 includes: a heat exchanging passage 37 as a first passage passing through a heat exchanging part; a cooling water passage 30 having a bypass passage 39 as a second passage that does not pass through the heat exchanging part; a water pump 20 to circulate cooling water in the cooling water passage 30 so as to allow reverse of a circulation direction; a first check valve 51 to prohibit flow of cooling water in the heat exchanging passage 37 when the cooling water is being circulated in a predetermined circulation direction by the water pump 20; and a second check valve 52 to prohibit flow of cooling water in the bypass passage 39 when the cooling water is being circulated in a direction different from the predefined circulation direction by the water pump 20.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an engine cooling system. [Background technology]

[0002] Conventionally, vehicles equipped with engines are provided with engine cooling systems that cool the engine by circulating coolant using a water pump. Some engine cooling systems can warm up the engine quickly by stopping the operation of the water pump until the engine is warmed up. However, stopping the operation of the water pump until the engine is warmed up can cause heat spots, where heat rises locally around the pistons of the engine.

[0003] Patent Document 1 discloses a vehicle engine warm-up device equipped with an electric pump that circulates coolant. The vehicle engine warm-up device of Patent Document 1 rotates the electric pump forward and backward when the coolant temperature is lower than a predetermined temperature, thereby effectively raising the coolant temperature without generating heat spots around heat-generating parts. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-16435 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the vehicle engine warm-up device disclosed in Patent Document 1 has a problem in that the electric pump repeatedly rotates forward and backward when the coolant temperature is lower than a predetermined temperature, resulting in noise. On the other hand, if the electric pump is stopped to suppress noise, the occurrence of the above-mentioned heat spots cannot be suppressed. Furthermore, the temperature detected by the coolant temperature sensor may differ greatly from the actual engine temperature, which may make it difficult to appropriately correct the fuel injection amount.

[0006] The present invention has been made in consideration of the above-mentioned problems, and has as its object to quickly warm up an engine while improving quietness and suppressing temperature variations. [Means for solving the problem]

[0007] The present invention provides an engine cooling system comprising a cooling water flow path having a first flow path that passes through a heat exchange component and a second flow path that does not pass through the heat exchange component, and a water pump that circulates the cooling water in the cooling water flow path so that the circulation direction of the cooling water can be reversed, characterized in that the system comprises a first check valve that prohibits the cooling water from flowing through the first flow path when the water pump is circulating the cooling water in a predetermined circulation direction, and a second check valve that prohibits the cooling water from flowing through the second flow path when the water pump circulates the cooling water in a circulation direction different from the predetermined circulation direction. [Effects of the Invention]

[0008] According to the present invention, it is possible to quickly warm up the engine while improving quietness and suppressing temperature variations. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing an example of the configuration of an engine cooling system. [Figure 2] FIG. 4 is a diagram for explaining the circulation direction of cooling water. [Figure 3]4 is a flowchart illustrating an example of a process performed by the engine cooling system. DETAILED DESCRIPTION OF THE INVENTION

[0010] The engine cooling system 1 according to the present invention includes a coolant flow path 30 having a heat exchange flow path 37 as a first flow path that passes through a heat exchange component and a bypass flow path 39 as a second flow path that does not pass through a heat exchange component, a water pump 20 that circulates the coolant in the coolant flow path 30 so that the circulation direction of the coolant can be reversed, a first check valve 51 that prohibits the coolant from flowing through the heat exchange flow path 37 when the water pump 20 is circulating the coolant in a predetermined circulation direction, and a second check valve 52 that prohibits the coolant from flowing through the bypass flow path 39 when the water pump 20 is circulating the coolant in a circulation direction different from the predetermined circulation direction. The engine cooling system 1 enables the engine to warm up quickly while improving noise reduction and suppressing temperature variations. [Example]

[0011] An engine cooling system 1 according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an example of the configuration of an engine cooling system 1. As shown in FIG. The engine cooling system 1 is provided in a vehicle in which a passenger rides. The vehicle in which the engine cooling system 1 is provided is equipped with devices that are provided in a general vehicle, and illustrations and descriptions of these devices will be omitted as appropriate.

[0012] The engine cooling system 1 according to the embodiment includes an engine 10, a water pump 20, a coolant flow path 30, a first check valve 51, a second check valve 52, a temperature sensor 55, a control unit 60, and the like.

[0013] The engine 10 is a driving source for propelling a vehicle. In this embodiment, the engine 10 is, for example, a multi-cylinder gasoline engine. The engine 10 is configured by integrally joining a cylinder block 11 and a cylinder head 12. Water jackets 13, 14 through which cooling water flows are formed around each cylinder of the cylinder block 11 and the cylinder head 12.

[0014] Water pump 20 can be driven to reverse the circulation direction of the coolant in coolant flow path 30 at any timing. Specifically, the circulation direction of water pump 20 is controlled based on a signal from control unit 60. Therefore, the coolant in coolant flow path 30 circulates in a predetermined circulation direction or a circulation direction different from the predetermined circulation direction by driving water pump 20. Water pump 20 in this embodiment is an electrically driven type that can be driven independently of engine 10, and is supplied with power from a battery provided in the vehicle, for example.

[0015] The coolant flow path 30 is a flow path through which coolant for cooling the engine 10 flows. The cooling water flow path 30 has a first inlet / outlet section 31 and a second inlet / outlet section 32 connected to the water jackets 13 and 14, respectively, a pump side flow path 34 connected to the water pump 20, and a switching flow path 36 that switches the flow path through which the cooling water flows depending on the circulation direction of the cooling water.

[0016] The first inlet / outlet part 31 is connected to each of the water jackets 13 and 14. The side of the first inlet / outlet part 31 opposite to the side connected to the water jackets 13 and 14 is connected to the water pump 20. The first inlet / outlet part 31 may be connected to either the water jacket 13 or the water jacket 14. The second inlet / outlet section 32 is connected to each of the water jackets 13 and 14. The second inlet / outlet section 32 is connected to the first branch section 33 on the side opposite to the side connected to the water jackets 13 and 14. The second inlet / outlet section 32 may be connected to either the water jacket 13 or the water jacket 14.

[0017] The switching flow path 36 is disposed between the first branch portion 33 and the second branch portion 35. The switching flow path 36 is branched from the second branch portion 35 of the pump-side flow path 34 and from the first branch portion 33, and is therefore composed of a heat exchange flow path 37 and a bypass flow path 39.

[0018] The heat exchange flow path 37 is a flow path that passes through a heat exchange component and corresponds to an example of a first flow path. The heat exchange flow path 37 is a flow path through which the coolant flows when the water pump 20 rotates forward and through which the coolant does not flow when the water pump 20 rotates reverse. In this embodiment, the heat exchange flow path 37 is composed of a pair of flow paths 37a and 37b arranged in parallel. A heater core 38a serving as a heat exchange component is disposed midway through one of the pair of flow paths 37a and 37b, and an EGR cooler 38b serving as a heat exchange component is disposed midway through the other flow path 37b. Here, the heat exchange component is a component that exchanges heat with the coolant and is not limited to the heater core 38a or the EGR cooler 38b. Furthermore, the heat exchange flow path 37 is not limited to being composed of a pair of flow paths 37a and 37b, and may be composed of either one of the flow paths 37a and the other flow path 37b.

[0019] Bypass flow path 39 is a flow path that does not pass through a heat exchange component and corresponds to an example of a second flow path. Bypass flow path 39 is a flow path through which the coolant bypasses the water pump when the water pump 20 rotates in the reverse direction, but through which the coolant does not flow when the water pump 20 rotates in the forward direction.

[0020] The coolant flow path 30 also has a radiator-side flow path 41 that passes through the radiator 40. One end of the radiator-side flow path 41 is connected to the middle of the pump-side flow path 34, and the other end is connected to the first branch portion 33 via a thermostat 42. When the thermostat 42 opens, part of the coolant flowing through the coolant flow path 30 flows into the radiator-side flow path 41, and the coolant is cooled by the radiator 40.

[0021] The first check valve 51 and the second check valve 52 control the flow of cooling water so that cooling water does not flow simultaneously through the heat exchange flow path 37 and the bypass flow path 39, and the circulation direction of the cooling water is reversed, thereby reversing the flow path through which the cooling water flows.

[0022] The first check valve 51 is disposed in the heat exchange flow path 37. In this embodiment, the first check valve 51 is provided on the first branch portion 33 side of the heat exchange flow path 37. The first check valve 51 opens to allow the coolant to flow through the heat exchange flow path 37 when the circulation direction corresponds to the forward rotation of the water pump 20 (see FIG. 2(b)). On the other hand, the first check valve 51 closes to prohibit the coolant from flowing through the heat exchange flow path 37 when the circulation direction corresponds to the reverse rotation of the water pump 20 (see FIG. 2(a)).

[0023] The second check valve 52 is disposed in the bypass flow path 39. In this embodiment, the second check valve 52 is provided in the bypass flow path 39 on the side of the first branch 33. The second check valve 52 closes when the circulation direction corresponds to the forward rotation of the water pump 20, thereby preventing the coolant from flowing into the bypass flow path 39 (see FIG. 2(b)). On the other hand, the second check valve 52 opens when the circulation direction corresponds to the reverse rotation of the water pump 20, thereby allowing the coolant to flow into the bypass flow path 39 (see FIG. 2(a)).

[0024] The temperature sensor 55 measures the temperature of the cooling water. In this embodiment, the temperature sensor 55 detects the temperature of the cooling water flowing through the first branch portion 33. Information on the temperature measured by the temperature sensor 55 is sent to the control unit 60.

[0025] The control unit 60 is, for example, an ECU (Electronic Control Unit). The control unit 60 has a hardware configuration including a CPU, a ROM, a RAM, etc. The ROM stores programs and predetermined information for controlling the engine 10 and the like in advance. The RAM is a work memory that temporarily stores programs and data. The CPU reads out the programs stored in the ROM, expands them in the RAM, and executes them to control the engine 10 and the like. The control unit 60 also controls the operation of the water pump 20 based on information about the temperature measured by the temperature sensor 55. The control unit 60 is not limited to being configured by one ECU, but may be configured by a plurality of ECUs working together. The control unit that controls the engine 10 and the control unit that controls the operation of the water pump 20 are not limited to being the same control unit, but may be different control units.

[0026] Next, the circulation direction of the cooling water in the cooling water flow path 30 will be described with reference to FIG. FIG. 2(a) is a diagram for explaining the direction in which the coolant circulates when the water pump 20 rotates in the reverse direction. 2(a), when water pump 20 rotates in the reverse direction, the coolant in coolant flow path 30 circulates from water pump 20 through pump-side flow path 34, second branch 35, bypass flow path 39, second check valve 52, first branch 33, second inflow / outflow path 32, engine 10 (water jackets 13, 14), and first inflow / outflow path 31 in this order. The circulation direction in FIG. 2(a) will be referred to as the reverse circulation direction hereinafter. In the reverse circulation direction, only the second check valve 52 is opened and the first check valve 51 remains closed, so that the cooling water flows only through the bypass passage 39 and does not flow through the heat exchange passage 37.

[0027] FIG. 2(b) is a diagram for explaining the circulation direction of the coolant when the water pump 20 rotates forward. 2(b), when water pump 20 rotates forward, the coolant in coolant flow path 30 circulates from water pump 20 through first inlet / outlet section 31, engine 10 (water jackets 13, 14), second inlet / outlet section 32, first branch section 33, first check valve 51, heat exchange flow path 37, second branch section 35, and pump-side flow path 34, in that order. The circulation direction in FIG. 2(b) will be referred to as the forward circulation direction hereinafter. In the forward circulation direction, only the first check valve 51 is open and the second check valve 52 remains closed, so that the cooling water flows only through the heat exchange passage 37 and does not flow through the bypass passage 39.

[0028] In this embodiment, the length of the flow path in the forward circulation direction shown in FIG. 2(b) is longer than the length of the flow path in the reverse circulation direction shown in FIG. 2(a) because the flow path does not pass through the bypass flow path 39.

[0029] Next, the processing performed by the engine cooling system 1 configured as described above will be described with reference to the flowchart of Fig. 3. The flowchart of Fig. 3 starts when the engine 10 is started. In S10, the control unit 60 determines whether or not the warm-up of the engine 10 has been completed. Specifically, the control unit 60 obtains information on the coolant temperature measured by the temperature sensor 55 and makes this determination by comparing the coolant temperature with a predetermined temperature (first temperature). The predetermined temperature is pre-stored in the ROM of the control unit 60. If the coolant temperature is equal to or higher than the predetermined temperature, the control unit 60 determines that the warm-up of the engine 10 has been completed, and proceeds to S12. On the other hand, if the coolant temperature is lower than the predetermined temperature, the control unit 60 determines that the warm-up of the engine 10 has not been completed, and proceeds to S11.

[0030] In S11, the control unit 60 drives the water pump 20 in reverse rotation so that the coolant flows in the coolant flow path 30 in the reverse circulation direction. Therefore, the coolant in the coolant flow path 30 flows in the reverse circulation direction as shown in FIG. 2(a). As described above, in the reverse circulation direction, the first check valve 51 is closed and the second check valve 52 is open, so that the coolant is prohibited from flowing through the heat exchange flow path 37 and flows only through the bypass flow path 39.

[0031] In this way, even when the engine 10 has not yet been warmed up, the occurrence of heat spots can be suppressed by circulating the coolant through the coolant flow path 30. Furthermore, by circulating the coolant through the coolant flow path 30, it is possible to suppress the deviation between the coolant temperature measured by the temperature sensor 55 and the actual coolant temperature in the engine 10 (water jackets 13, 14). Furthermore, since the coolant is prohibited from flowing through the heat exchange flow path 37, the heat obtained from the engine 10 by the coolant is not dissipated to the heat exchange components, allowing the engine 10 to be warmed up quickly.

[0032] In S12, the control unit 60 drives the water pump 20 in the forward direction so that the coolant flows in the coolant flow path 30 in the forward circulation direction. Therefore, the coolant in the coolant flow path 30 flows in the forward circulation direction as shown in FIG. 2(b). As described above, in the forward circulation direction, the first check valve 51 opens and the second check valve 52 closes, so that the coolant is prohibited from flowing through the bypass flow path 39 and flows only through the heat exchange flow path 37. Note that when the water pump 20 is driven in the forward direction from the state in which it was driven in the reverse direction in S11, it is preferable to gradually rotate the water pump in the forward direction so that a large amount of low-temperature coolant in the heat exchange flow path 37 does not flow into the engine 10.

[0033] In this way, when the warm-up of the engine 10 is complete (when the warm-up is complete), the coolant is circulated through the heat exchange components within the coolant flow path 30, thereby cooling the engine 10 and allowing the heat exchange components to perform heat exchange. When the coolant temperature rises further while the coolant is flowing in the forward circulation direction, the thermostat 42 opens, and part of the coolant flows into the radiator-side flow path 41, where it is cooled by the radiator 40, thereby lowering the coolant temperature. The temperature of the coolant when the thermostat 42 opens is higher than the predetermined temperature that is compared with the coolant temperature in S10.

[0034] After the process of S11 or S12, the process returns to S10 and repeats the processes of S10 to S12. The flowchart of Fig. 3 ends when the driving of the engine 10 ends.

[0035] As described above, engine cooling system 1 of the present embodiment includes first check valve 51 that prohibits coolant from flowing through heat exchange passage 37 when water pump 20 is circulating coolant in a predetermined circulation direction, and second check valve 52 that prohibits coolant from flowing through bypass passage 39 when water pump 20 is circulating coolant in a circulation direction different from the predetermined circulation direction. In engine cooling system 1, water pump 20 is circulated in the predetermined circulation direction to minimize forward and reverse rotation until warm-up of engine 10 is complete, thereby achieving quieter operation than when forward and reverse rotation is repeated.

[0036] Furthermore, since the engine cooling system 1 of this embodiment circulates the coolant even when the engine 10 has not yet warmed up, it is possible to reduce the deviation between the coolant temperature measured by the temperature sensor 55 and the actual coolant temperature inside the engine 10 compared to when the coolant is not circulated. Therefore, even when correcting the fuel injection amount of the engine 10 based on the coolant temperature measured by the temperature sensor 55, the accuracy of the correction can be improved.

[0037] Furthermore, in the engine cooling system 1 of this embodiment, when the engine 10 has not yet warmed up, the coolant flows through the bypass flow path 39, which allows the engine 10 to warm up more quickly than if the coolant always flows through the heat exchange flow path 37. Furthermore, the length of the flow path in the circulation direction via the bypass flow path 39 is short, and the amount of coolant circulated is small, allowing the engine 10 to warm up more quickly.

[0038] Furthermore, since the engine cooling system 1 of this embodiment does not require the use of special valves, the cost of the entire system can be reduced. Furthermore, since the engine cooling system 1 of this embodiment uses check valves, it is not necessary to control the valves, which reduces the processing load on the control unit 60 and reduces the cost of the entire system.

[0039] Furthermore, according to the engine cooling system 1 of this embodiment, during warm-up, the water pump 20 is driven to circulate the coolant in a predetermined circulation direction, thereby preventing heat dissipation from the coolant to the heat exchange components, thereby enabling the engine 10 to warm up quickly.

[0040] Furthermore, according to the engine cooling system 1 of this embodiment, when the warm-up is complete, the water pump 20 is driven to circulate the cooling water in a direction different from the predetermined circulation direction, so that the same processing as that of a normal engine cooling system can be performed.

[0041] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and modifications and the like are possible within the scope of the present invention.

[0042] In the embodiment described above, the first check valve 51 and the second check valve 52 are disposed adjacent to each other at the first branch section 33. By disposing the first check valve 51 and the second check valve 52 adjacent to each other in this way, it is possible to improve the ease of assembly or maintenance of the engine cooling system 1. However, the arrangement of the first check valve 51 and the second check valve 52 is not limited to the above-described arrangement, and any arrangement is possible as long as the first check valve 51 is disposed on the heat exchange passage 37 and the second check valve 52 is disposed on the bypass passage 39.

[0043] In the above-described embodiment, the first check valve 51 is arranged on the heat exchange flow path 37, and the second check valve 52 is arranged on the bypass flow path 39. However, this is not limited to this case, and a three-way valve or the like that switches the flow path in response to a signal from the control unit 60 may be arranged on the first branch section 33. [Explanation of symbols]

[0044] 1: Engine cooling system 10: Engine 13, 14: Water jacket 20: Water pump 37: Heat exchange passage (first passage) 38a: Heater core (heat exchange part) 38b: EGR cooler (heat exchange part) 39: Bypass passage (second passage) 51: First check valve 52: Second check valve 55: Temperature sensor 60: Control unit

Claims

1. a cooling water flow path having a first flow path that passes through a heat exchange element and a second flow path that does not pass through the heat exchange element; a water pump that circulates the cooling water in the cooling water flow path so that the direction of circulation of the cooling water can be reversed, a first check valve that prohibits the cooling water from flowing through the first flow path when the cooling water is circulated in a predetermined circulation direction by the water pump; and a second check valve that prohibits the cooling water from flowing through the second flow path when the water pump is circulating the cooling water in a direction different from the predetermined circulation direction.

2. 2. The engine cooling system according to claim 1, wherein, during warm-up, the water pump is driven to circulate the cooling water in the predetermined circulation direction.

3. 3. The engine cooling system according to claim 1, wherein, when warm-up is complete, the water pump is driven to circulate the cooling water in a direction different from the predetermined direction.

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