Thermal Management System

Abstract

To provide a thermal management system capable of suppressing an increase in size of a multi-way valve without requiring a large-output actuator for the multi-way valve. In a thermal management system equipped with a four-way valve with a first outlet port connected to a high-temperature radiator, a second outlet port connected to a heater core, and a third outlet port connected to a water-to-water heat exchanger, the pump duty of the water pump in the high-temperature circuit is set low in the region where the opening area of ​​the third outlet port increases, thereby reducing the fluid pressure applied to the drive valve of the four-way valve and thereby reducing the sliding resistance between the fixed valve and the drive valve.

Description

[Technical Field]

[0001] The present invention relates to thermal management systems, and more particularly to improvements in the control of pumps that circulate fluids in circuits. [Background technology]

[0002] In recent years, with the increasing electrification of automobiles, thermal management systems have become more complex in order to meet thermal management requirements such as heating the vehicle interior and raising the temperature of the battery. As disclosed in Patent Document 1, this type of thermal management system generally employs a multi-way valve as a valve for switching the circulation path of the heat medium (fluid) in a thermal management circuit through which the heat medium circulates. This multi-way valve generally changes the opening of the ports connected to each circuit by sliding and rotating a drive valve relative to a fixed valve.

[0003] Furthermore, as the thermal management circuit becomes more complex due to the increasing complexity of the thermal management system, the flow rate of the heat transfer medium in the entire circuit is also increasing, and therefore, a multi-way valve capable of handling a large flow rate is required. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-84424 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-9668 Summary of the Invention [Problem to be solved by the invention]

[0005] In a multi-way valve designed to handle large flow rates, the fluid pressure acting on the valve may become high depending on the rotational position of the valve, which tends to increase the sliding resistance between the fixed valve and the valve. To address this, an actuator with a large output is required to increase the rotational force of the valve.

[0006] However, in this case, the actuator becomes larger, which in turn results in the entire multi-way valve becoming larger, which may lead to an increase in the size of the thermal management system, a rise in manufacturing costs, and an increase in power consumption, leaving room for improvement.

[0007] The present invention has been made in consideration of the above points, and its purpose is to provide a thermal management system that can prevent the multi-way valve from becoming too large without requiring a high-output actuator for the multi-way valve. [Means for solving the problem]

[0008] The solution of the present invention for achieving the above object is based on a thermal management system including a pump for circulating a fluid in a circuit, a pump control unit for controlling the pump, and a multi-way valve having a plurality of outlets for switching the circuit through which the fluid flows. This thermal management system is characterized in that, when the multi-way valve is operated to change the flow rate ratio of the fluid at each outlet, the pump control unit controls the multi-way valve to reduce the flow rate through the multi-way valve.

[0009] This feature allows the pump to be controlled to reduce the flow rate through the multi-way valve in the operating range of the multi-way valve, where the sliding resistance inside the multi-way valve (the sliding resistance between the fixed valve and the drive valve) could increase, thereby reducing the sliding resistance. This eliminates the need for a high-output actuator to obtain a high valve rotation force, making it possible to prevent the multi-way valve from becoming larger. [Effects of the Invention]

[0010] In the present invention, when the multi-way valve provided in the thermal management system changes the flow rate ratio of the fluid at each outlet, the pump control unit controls to reduce the flow rate through the multi-way valve. This reduces the sliding resistance inside the multi-way valve, eliminating the need for a high-output actuator to obtain high valve rotation force, and making it possible to prevent the multi-way valve from becoming larger. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing a high-temperature circuit in a thermal management system according to an embodiment, and a portion of various circuits that exchange heat with the high-temperature circuit. [Figure 2] FIG. 2(a) is a schematic cross-sectional view showing the valve periphery in a four-way valve provided in the high-temperature circuit of a thermal management system according to an embodiment, and FIG. 2(b) is a diagram showing an example of the transition of the opening area for each outlet port as the four-way valve operates. [Figure 3] FIG. 3(a) is a functional block diagram of the pump ECU, and FIG. 3(b) is a timing chart showing an example of the operation when the pump duty is changed. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the present invention is applied to a thermal management system mounted on an electric vehicle. Note that the thermal management system according to the present invention is not limited to electric vehicles, but can also be applied to hybrid vehicles, plug-in hybrid vehicles, etc.

[0013] -Circuit configuration of thermal management system- FIG. 1 is a diagram showing a high-temperature circuit 2 and a portion of various circuits 3, 4, and 5 that exchange heat with the high-temperature circuit 2 in a thermal management system 1 according to this embodiment.

[0014] As shown in FIG. 1, the thermal management system 1 includes a high-temperature circuit 2, a low-temperature circuit 3, a refrigeration cycle 4, and a battery circuit 5.

[0015] The high temperature circuit 2 includes a main circuit 2A, a heater core circuit 2B, and a battery heating circuit 2C.

[0016] The main circuit 2A is composed of a water pump 21, a condenser 61, an electric heater 22, a four-way valve 23, a high-temperature (HT) radiator 24, and a reservoir tank 25, which are connected in this order by piping 26. The outlet side of the electric heater 22 is connected to an inlet port 23a of the four-way valve 23 by piping 26a, and a first outlet port 23b of the four-way valve 23 is connected to the high-temperature radiator 24 by piping 26b. The heater core circuit 2B is configured by arranging a heater core 27 in a pipe 26c that connects the second outlet port 23c of the four-way valve 23 and the upstream side of the reservoir tank 25.

[0017] The battery heating circuit 2C is configured by arranging a water-water heat exchanger (heat exchanger for raising the battery temperature) 62 in the pipe 26d that connects the third outlet port 23d of the four-way valve 23 and the downstream side of the high-temperature radiator 24.

[0018] The water pump 21 discharges a heat medium at a predetermined discharge rate in accordance with a control command signal from a pump ECU 100 (see FIG. 3A), which will be described later, and circulates the heat medium through the high-temperature circuit 2. Antifreeze (e.g., an ethylene glycol solution) is used as the heat medium circulating through the high-temperature circuit 2. The condenser 61 exchanges heat between the heat medium circulating through the high-temperature circuit 2 and the refrigerant circulating through the refrigeration cycle 4. The electric heater 22 heats the heat medium in accordance with a control command signal from an ECU (not shown). The four-way valve 23 adjusts the rotational position of a drive valve 234 (see FIG. 2A, which shows a schematic cross section of the four-way valve 23), which will be described later, in accordance with a control command signal from the ECU (not shown), thereby adjusting the valve opening (opening area) of each of the outlet ports 23b, 23c, and 23d. The heater core 27 exchanges heat between the heat medium circulating through the high-temperature circuit 2 and the air blown into the vehicle cabin, thereby heating the air. The reservoir tank 25 stores a portion of the heat medium in the high-temperature circuit 2, thereby maintaining the pressure and circulation amount of the heat medium in the high-temperature circuit 2.

[0019] The low-temperature circuit 3 is a circuit for cooling a smart power unit (SPU) and a power control unit (PCU), not shown, and is composed of a low-temperature (LT) radiator 31 that exchanges heat with the high-temperature radiator 24, as well as a water pump, the smart power unit, the power control unit, an oil cooler, a step-up / step-down converter, etc., all of which are connected in sequence by piping 32.

[0020] The refrigeration cycle 4 is a circuit for cooling the vehicle interior and heating the heat medium circulating in the high-temperature circuit 2, and in addition to the condenser 61, includes a compressor (not shown), an expansion valve, an evaporator, a chiller for exchanging heat with the heat medium circulating in the battery circuit 5, and the like, all of which are connected by refrigerant piping 41 to enable the circulation of the refrigerant.

[0021] The battery circuit 5 is a circuit for raising the temperature of the battery, and in addition to the water-water heat exchanger 62, a water pump, chiller, five-way valve, electric heater, battery, reservoir tank, etc. (not shown) are connected by piping 51 so that the heat medium can circulate.

[0022] The functions of the devices provided in the low-temperature circuit 3, the refrigeration cycle 4, and the battery circuit 5 are publicly known (for example, as disclosed in Patent Document 1), and therefore a description thereof will be omitted here.

[0023] -Four-way valve configuration- Next, the schematic configuration of the four-way valve 23 provided in the high-temperature circuit 2 will be described with reference to Fig. 2(a). Fig. 2(a) is a schematic cross-sectional view showing the periphery of the valves 231 and 234 in the four-way valve 23. Note that the configuration of the four-way valve 23 is not limited to that shown in Fig. 2(a).

[0024] 2(a), four-way valve 23 has drive shaft 233 housed inside casing 232 to which fixed valve 231 is attached, and drive valve 234 attached to the tip of drive shaft 233 so as to rotate integrally with drive shaft 233. Fixed valve 231 and drive valve 234 each have openings corresponding to outlet ports 23b, 23c, and 23d (only some of the openings are visible in FIG. 2(a), and the arrow indicates the state where the heat medium flows out at the portion where the opening of fixed valve 231 and the opening of drive valve 234 communicate).

[0025] The drive shaft 233 includes a holder portion 235 and an axis portion 236. An electric motor 237 is attached to the base end portion (the upper end portion in FIG. 2(a)) of the drive shaft 233, and the drive valve 234 rotates relative to the fixed valve 231 as the drive shaft 233 rotates due to the operation of the electric motor 237. This changes the communication state of the openings provided in each of the valves 231 and 234, thereby changing the opening area for each of the ports 23b, 23c, and 23d, and thereby changing the flow rate of the heat medium toward the high-temperature radiator 24, the flow rate of the heat medium toward the heater core 27, and the flow rate of the heat medium toward the water-water heat exchanger 62.

[0026] More specifically, a lever 238 is fixed to the upper surface of the drive valve 234, and a compression spring SP1 is interposed in a compressed state between this lever 238 and the holding part 235. The biasing force of this compression spring SP1 is in a direction that presses the drive valve 234 toward the fixed valve 231, so that no gap is created between the drive valve 234 and the fixed valve 231, and the drive valve 234 slides relative to the fixed valve 231.

[0027] Additionally, a torsion spring SP2 is disposed around the outer periphery of the holding portion 235. The biasing force of this torsion spring SP2 acts as a rotational force in one direction on the driven valve 234 via the holding portion 235 and the shaft portion 236. For this reason, by operating the electric motor 237, a rotational force in the other direction is applied to the torsion spring SP2, increasing the reaction force of the torsion spring SP2 (the reaction force in one direction), and then weakening the rotational force from the electric motor 237, the driven valve 234 is rotated by the reaction force of the torsion spring SP2.

[0028] Fig. 2(b) is a diagram showing an example of the transition of changes in the opening area of ​​each of the outflow ports 23b, 23c, and 23d in association with the operation of the four-way valve 23. In Fig. 2(b), the dashed line indicates the change in the opening area of ​​the first outflow port (port connected to the high-temperature radiator 24) 23b, the dashed line indicates the change in the opening area of ​​the second outflow port (port connected to the heater core 27) 23c, and the solid line indicates the change in the opening area of ​​the third outflow port (port connected to the water-water heat exchanger 62) 23d.

[0029] As described above, in this embodiment, at a valve opening of 0° (the initial rotational position of the actuated valve 234), the opening area for the first outlet port 23b is maximum, and the opening areas for the second outlet port 23c and the third outlet port 23d are minimum. As the valve opening increases from this state (increasing toward the positive side in the rotational direction of the actuated valve 234), the opening area for the first outlet port 23b gradually decreases, and the opening area for the second outlet port 23c gradually increases. Then, from the point where the opening area for the first outlet port 23b is minimum and the opening area for the second outlet port 23c is maximum (a valve opening of 54° in the figure), as the valve opening increases further, the opening area for the second outlet port 23c gradually decreases, and the opening area for the third outlet port 23d gradually increases. Then, from the point where the opening area for the second outlet port 23c is minimum and the opening area for the third outlet port 23d is maximum (the point where the valve opening is 108° in the figure), as the valve opening increases further, the opening area for the third outlet port 23d gradually decreases and the opening area for the first outlet port 23b gradually increases.

[0030] In the four-way valve 23 of this embodiment, the fluid pressure inside the casing 232 of the four-way valve 23 increases between the time when the valve opening reaches 90° and the time when it reaches 135°, and the sliding resistance between the fixed valve 231 and the drive valve 234 is likely to increase. Hereinafter, this period (valve opening period) will be referred to as the choke occurrence region.

[0031] In this embodiment, in order to suppress an increase in sliding resistance between the fixed valve 231 and the drive valve 234 in this choke region, the rotation speed (duty ratio) of the water pump 21 is reduced so as to reduce the fluid pressure inside the casing 232 of the four-way valve 23. The configuration for performing this control will be described below.

[0032] -Pump ECU- 3(a) is a functional block diagram of a pump ECU 100 that adjusts the duty ratio of the water pump 21. As shown in FIG. 3(a), the pump ECU 100 includes a valve opening degree recognition unit 110 and a pump duty adjustment unit 120.

[0033] The valve opening recognition unit 110 is a functional unit that recognizes the valve opening, which is the rotational position of the drive valve 234. To recognize this valve opening, the rotational position of the drive valve 234 may be recognized by recognizing a control command signal given to the electric motor 237, or the rotational position of the drive valve 234 may be detected by a sensor or the like.

[0034] The pump duty adjustment unit 120 adjusts the pump duty (sets the pump duty low for a predetermined time from the point in time when the valve opening reaches a predetermined opening) in accordance with the valve opening recognized by the valve opening recognition unit 110, thereby controlling the pump rotation speed (discharge rate of the heat medium) of the water pump 21. Specifically, the pump duty can be set low in the aforementioned choke-up occurrence region (the valve opening period during which sliding resistance between the fixed valve 231 and the drive valve 234 increases: from the point in time when the valve opening reaches 90° to the point in time when the valve opening reaches 135°) by specifying the time during which the pump duty is set low (set to be lower than the pump duty during other valve opening periods). This reduces the fluid pressure inside the casing 232 of the four-way valve 23, thereby keeping the sliding resistance between the fixed valve 231 and the drive valve 234 low. The amount of reduction in the pump duty in this case is set by experiment or simulation. For example, it is set to a value that allows the drive valve 234 to rotate smoothly (enables the sliding resistance between the drive valve 234 and the fixed valve 231 to be sufficiently small) without requiring the electric motor 237 to be made larger.

[0035] In particular, in a configuration in which the drive valve 234 is rotated in response to the rotational force of the electric motor 237 and the reaction force of the torsion spring SP2 as described above, when the drive valve 234 is rotated in the negative direction (e.g., when the valve opening is shifted from 135° to 90°), the torsion spring SP2 is loosened, and so there is no need to set the pump duty low. For this reason, in this embodiment, the pump duty is set low for a predetermined period of time when the drive valve 234 is rotated in the positive direction and the valve opening is shifted from 90° to 135°. Furthermore, in the thermal management system 1 of this embodiment, the heater core 27 of the high-temperature circuit 2 including the pump 21 contributes to heating the vehicle cabin. For this reason, it is not preferable to set the pump duty low when there is a request for heating the vehicle cabin. Furthermore, it may not be preferable to set the pump duty low due to other requests, not just when there is a request for heating the vehicle cabin. For this reason, in this embodiment, a condition for permitting the pump duty to be set low is that there is a request to increase the battery temperature and there are no other requests that cannot be fulfilled due to setting the pump duty low. For example, a minimum required value for the opening area (opening area toward the heater core 27) of the second outflow port 23c necessary to fulfill the request for heating the vehicle interior is set in advance, and when there is a request for heating the vehicle interior, if the opening area of ​​the second outflow port 23c cannot be secured to be equal to or greater than this minimum required value, setting the pump duty low is prohibited.

[0036] -Pump duty adjustment operation- Next, the pump duty adjustment operation in the thermal management system 1 configured as described above will be described with reference to the timing chart of FIG. 3(b) (a timing chart showing an example of the operation when changing the pump duty).

[0037] As described above, the condition for allowing a low pump duty is that no requests that would be unable to be fulfilled by setting the pump duty low are present. Therefore, when a battery warming-up request alone is present (when no other requests that would be unable to be fulfilled by setting the pump duty low are present), the pump duty is set low when the valve opening reaches θ1 (e.g., 90°). In the example shown in FIG. 3(b), a battery warming-up request alone occurs at time T1 in the figure, and the valve opening reaches θ1 at time T2 in the figure. Therefore, the pump duty is set low for a predetermined time from time T2 to time T3 in the figure (the pump duty is reduced from D1 to D2 in the figure). This predetermined time is set to, for example, 15 seconds. However, this value is not limited to this. This predetermined time is set in advance to be sufficient for the valve opening to reach 135° from 90° (in FIG. 3(b) the valve opening reaches θ2 (e.g., 135°) before timing T3). After this predetermined time has elapsed, the pump duty is returned to its original value (timing T3 in the figure).

[0038] -Effects of the embodiment- As described above, in this embodiment, in the choke region, the pump duty is set low to reduce the flow rate through the four-way valve 23, lowering the fluid pressure inside the casing 232 of the four-way valve 23, thereby reducing the sliding resistance between the fixed valve 231 and the drive valve 234. This eliminates the need for a high-output electric motor 237 to increase the rotational force of the drive valve 234, making it possible to prevent the four-way valve 23 from becoming larger. As a result, it is possible to prevent the thermal management system 1 from becoming larger, the manufacturing costs from rising, the amount of power consumed, and the like.

[0039] -Other embodiments- The present invention is not limited to the above-described embodiments, and all modifications and applications within the scope of the claims and equivalents thereto are possible.

[0040] For example, in the above embodiment, the four-way valve 23 was described as an example in which the choke region occurs between the point at which the valve opening reaches 90° and the point at which it reaches 135°, but the choke region is not limited to this.

[0041] Furthermore, in the above embodiment, an example has been described in which the sliding resistance between the valves in the four-way valve 23 provided in the high-temperature circuit 2 is reduced. However, the present invention is not limited to this, and can also be applied to a case in which the sliding resistance between the valves in a five-way valve provided in the battery circuit 5 is reduced. [Industrial Applicability]

[0042] The present invention is applicable to the control of a water pump provided in a high-temperature circuit of a thermal management system mounted on an electric vehicle. [Explanation of symbols]

[0043] 1...Thermal management system 2...High temperature circuit 21...Water pump (pump) 23...Four-way valve (multi-way valve) 23b...First outlet port 23c...Second outlet port 23d...Third outflow port 100...Pump ECU (pump control unit) 120...Pump duty adjustment section

Claims

[Claim 1] A thermal management system including a pump for circulating a fluid in a circuit, a pump control unit for controlling the pump, and a multi-way valve having a plurality of outlets for switching the circuit through which the fluid flows, A thermal management system characterized in that when the flow rate ratio of the fluid at each outlet is changed by operating the multi-way valve, the pump control unit controls to reduce the flow rate flowing to the multi-way valve.

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