vehicle

Abstract

Ensure that the pumps that circulate the refrigerant to multiple heat sources are properly operated. [Solution] The ECU performs a process that includes the steps of acquiring the coolant temperature (S100), acquiring the oil temperature (S102), calculating a first requested flow rate from the oil temperature and a map (S104), calculating a second requested flow rate from the coolant temperature and a map (S106), setting the first requested flow rate as the requested amount if the first requested flow rate is greater than the second requested flow rate (YES in S108) (S110), setting the second requested flow rate as the requested amount if the first requested flow rate is less than or equal to the second requested flow rate (NO in S108) (S112), and calculating the output of the water pump from the coolant temperature, the requested amount and a map (S114).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a vehicle.

BACKGROUND ART

[0002] For example, Japanese Patent Laid-Open No. 2008-303918 (Patent Document 1) discloses a technology that, when the temperature of ATF (Automatic Transmission Fluid) which is the working oil of an automatic transmission reaches a cooling start temperature, switches the output of a switching valve to cause an oil cooler to cool the ATF.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0003]

PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] For example, a hybrid vehicle is equipped with a plurality of heat sources such as an inverter in addition to an automatic transmission. A configuration is conceivable in which a common pump is used to circulate a coolant in order to cool such a plurality of heat sources. Therefore, it is conceivable to operate the pump on the assumption that the heat generation amounts of both the automatic transmission and the inverter increase. However, since the period in which the heat generation amount in the automatic transmission increases and the period in which the heat generation amount in the inverter increases do not necessarily overlap, operating the pump on the assumption that both are cooled in parallel may lead to deterioration of losses and reduction in the service life of components in some cases.

[0005] The present disclosure has been made to solve the above-described problems, and an object thereof is to provide a vehicle that appropriately operates a pump for circulating a coolant to a plurality of heat sources.

MEANS FOR SOLVING THE PROBLEMS

[0006] A vehicle relating to a certain aspect of this disclosure includes a transmission mounted on the vehicle, an inverter, a cooling system for cooling the hydraulic fluid of the transmission and the inverter, and a control device for controlling the operation of the cooling system. The cooling system includes an oil cooler through which the hydraulic fluid of the transmission flows, a refrigerant passage through which the refrigerant flows to the inverter, and a pump for circulating refrigerant between the oil cooler and the refrigerant passage. The control device controls the output of the pump using the higher of a first required flow rate, which is the flow rate of refrigerant required in the oil cooler, and a second required flow rate, which is the flow rate of refrigerant required in the refrigerant passage.

[0007] In this configuration, if the first required flow rate is higher than the second required flow rate, the pump output is controlled using the first required flow rate, thereby effectively cooling the transmission's hydraulic fluid. Furthermore, if the second required flow rate is higher than the first required flow rate, the pump output is controlled using the second required flow rate, thereby effectively cooling the inverter. As a result, over-driving of the pump can be suppressed.

[0008] In one embodiment, the control device controls the pump output using the upper limit value if the pump output is greater than the upper limit value set when the vehicle is in a predetermined state.

[0009] This approach prevents the pump's output from becoming unnecessarily high, thereby reducing any discomfort the user might experience.

[0010] In one embodiment, the control device sets a first required flow rate using the temperature of the hydraulic fluid and a second required flow rate using the temperature of the refrigerant.

[0011] In this way, the first and second required flow rates can be set with high precision. [Effects of the Invention]

[0012] According to this disclosure, it is possible to provide a vehicle that properly operates a pump that circulates a refrigerant to multiple heat sources. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows an example of the configuration of a vehicle according to this embodiment. [Figure 2] This flowchart shows an example of a process performed by the ECU. [Figure 3] This figure shows an example of the relationship between oil temperature and the first required flow rate. [Figure 4] This figure shows an example of the relationship between cooling water temperature and the second required flow rate. [Figure 5] This diagram shows an example of the relationship between coolant temperature, coolant demand, and water pump output in tabular form. [Figure 6] This diagram illustrates an example of how to set the upper limit of the guard value. [Modes for carrying out the invention]

[0014] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0015] The following describes an example of the configuration of vehicle 1 according to this embodiment. Figure 1 is a diagram showing an example of the configuration of vehicle 1 according to this embodiment. In this embodiment, as shown in Figure 1, vehicle 1 comprises a cooling device 5, an inverter 10, a transmission 40, a power transmission gear 60, drive wheels 62, and an ECU (Electronic Control Unit) 100. Vehicle 1 is, for example, a hybrid vehicle that uses an engine and an MG (Motor Generator) (neither of which are shown) as power sources. Note that vehicle 1 may be any vehicle equipped with an inverter 10 and a transmission 40, and may be, for example, an electric vehicle that uses only an MG as a power source.

[0016] The transmission 40 may be an automatic transmission and is not particularly limited, and for example, it may be a stepped automatic transmission or a continuously variable automatic transmission. For example, ATF is stored in the transmission 40. Inside the transmission 40, for example, a mechanical or electric oil pump operates in conjunction with the rotation of the rotating shaft within the transmission 40, and the operation of the oil pump causes ATF to circulate inside the transmission and flow through the oil passage in the oil cooler 20.

[0017] The output shaft of the engine is connected to the input shaft of the transmission 40. A power transmission gear 60 including a speed reducer, a differential device and the like is connected to the output shaft of the transmission 40. The left and right drive wheels 62 of the vehicle 1 are coupled to the power transmission gear 60.

[0018] The cooling device 5 includes a refrigerant passage 6, a refrigerant passage 7 in the inverter 10, a refrigerant passage 8 in the oil cooler 20 provided in the transmission 40, a water pump 30 provided in the middle of the refrigerant passage 6, a reserve tank 32, and a radiator 50. The refrigerant passage 6, the refrigerant passage 7 provided in the inverter 10, and the refrigerant passage 8 provided in the oil cooler 20 are connected to form an annular refrigerant passage. The water pump 30 is provided in the middle of the refrigerant passage 6, and circulates the refrigerant in the annular refrigerant passage in response to a control signal from the ECU 100.

[0019] The ECU 100 sets the output (driving amount) of the water pump 30, and transmits a driving command (duty command) to the water pump 30 so as to achieve the set output. The ECU 100, for example, sets any ratio from 0% to 100% with the maximum driving amount defined as 100% output as the driving command, and transmits the set driving command to the water pump 30. The water pump 30 operates in response to the driving command from the ECU 100. The reserve tank 32 stores a part of the coolant. The radiator 50 is a heat exchanger configured to allow heat exchange between outside air and the refrigerant. The refrigerant passage 7 provided in the inverter 10 is, for example, disposed at a position close to a heat source such as a switching element of the inverter 10, and is provided so that heat exchange is performed between the heat source and the refrigerant. Further, the refrigerant passage 8 provided in the oil cooler 20 is, for example, disposed at a position close to a pipe through which hydraulic oil (hereinafter referred to as ATF (Automatic Transmission Fluid)) circulating in the transmission 40 inside the oil cooler 20 flows, and is provided so that heat exchange is performed between the ATF and the refrigerant.

[0020] The inverter 10 performs power conversion between a battery (not shown) and an electric load. The electric load includes, for example, a motor-generator (MG) and the like. The MG has a function as an electric motor and a function as a generator. The MG may drive the drive wheels 62, or may drive wheels other than the drive wheels 62. The inverter 10 converts DC power of the battery into AC power in response to a control command from the ECU 100, and supplies the AC power to the electric load (MG). Alternatively, the inverter 10 converts AC power (regenerative power) from the electric load (MG) into DC power in response to a control command from the ECU, and supplies the DC power to the battery.

[0021] The battery is, for example, a rechargeable DC power supply (secondary battery), and is configured by stacking a plurality of unit cells (battery cells). The battery may be composed of, for example, a lithium-ion battery.

[0022] The ECU 100 is connected to a coolant temperature sensor 102 and an oil temperature sensor 104. The coolant temperature sensor 102 detects the temperature Tw of the coolant in the coolant passage 6 (hereinafter referred to as coolant temperature Tw) and transmits a signal indicating the detected coolant temperature Tw to the ECU 100. The oil temperature sensor 104 detects the temperature To of the ATF in the transmission 40 (hereinafter referred to as oil temperature To) and transmits a signal indicating the detected oil temperature To to the ECU 100.

[0023] The ECU 100 includes a CPU (Central Processing Unit) and memory (neither of which are shown). Based on signals from the coolant temperature sensor 102, the oil temperature sensor 104, and various other sensors, as well as information such as maps and programs stored in memory, the ECU 100 controls each component (water pump 30) so that the vehicle 1 reaches a desired state. The ECU 100 performs control processing such as operating the water pump 30. The ECU 100 may be composed of multiple ECUs, each with its own assigned function.

[0024] As described above, vehicle 1 is equipped with multiple heat sources, such as an inverter 10 in addition to the transmission 40. To cool these multiple heat sources, one possible configuration is to circulate a refrigerant using a common water pump 30. Therefore, the water pump 30 is operated assuming that the heat generated by both the transmission 40 and the inverter 10 increases. However, since the period when the heat generated by the transmission 40 increases and the period when the heat generated by the inverter 10 increases do not necessarily overlap, operating the water pump 30 assuming that both will be cooled in parallel may lead to increased losses or a reduction in the lifespan of the components.

[0025] Therefore, in this embodiment, the ECU 100 controls the output of the water pump 30 using the higher of the first required flow rate, which is the flow rate of refrigerant required in the oil cooler 20, and the second required flow rate, which is the flow rate of refrigerant required in the refrigerant passage 7 provided in the inverter 10.

[0026] In this configuration, if the first required flow rate is higher than the second required flow rate, the output of the water pump 30 is controlled using the first required flow rate, thereby effectively cooling the hydraulic fluid of the transmission 40. Furthermore, if the second required flow rate is higher than the first required flow rate, the output of the water pump 30 is controlled using the second required flow rate, thereby effectively cooling the inverter 10. As a result, over-driving of the water pump 30 can be suppressed.

[0027] The following describes an example of the processing performed by ECU100, with reference to Figure 2. Figure 2 is a flowchart showing an example of the processing performed by ECU100.

[0028] In step 100 (hereinafter referred to as S), the ECU 100 obtains the coolant temperature. The ECU 100 obtains the coolant temperature Tw using the detection result of the coolant temperature sensor 102. The process then moves to S102.

[0029] In S102, ECU100 obtains the oil temperature To. ECU100 obtains the oil temperature To using the detection result of the oil temperature sensor 104. The process then moves to S104.

[0030] In S104, the ECU100 calculates the first required flow rate F(1) using the oil temperature To of the transmission 40 and the map. For example, the ECU100 calculates the first required flow rate F(1) from the oil temperature To using the map shown in Figure 3. Figure 3 is a diagram showing an example of the relationship between oil temperature To and the first required flow rate F(1). The vertical axis in Figure 3 represents the first required flow rate F(1). The horizontal axis in Figure 3 represents the oil temperature To. LN1 (dashed line) in Figure 3 shows the change in the reference value of the first required flow rate F(1) in response to a change in oil temperature To. LN2 (solid line) in Figure 3 shows the change in the set value of the first required flow rate F(1) in response to a change in oil temperature To.

[0031] As shown in LN1 of Figure 3, the reference value of the first requested flow rate F(1) is set to increase in proportion to the rise in oil temperature To until it rises to a predetermined oil temperature To(0), and once it exceeds the predetermined oil temperature To(0), it is set to remain constant regardless of the oil temperature To. The ECU 100 may set the first requested flow rate F(1) based on the reference value of the first requested flow rate F(1), or it may set the first requested flow rate F(1) based on the setting value of the first requested flow rate F(1) set as shown in LN2 of Figure 3 by stepwise changing the first requested flow rate F(1) in response to changes in oil temperature To based on the reference value shown in LN1 of Figure 3. The process then proceeds to S106.

[0032] In S106, the ECU100 calculates the second required flow rate F(2) using the coolant temperature Tw and the map. For example, the ECU100 calculates the second required flow rate F(2) from the coolant temperature Tw using the map shown in Figure 4. Figure 4 is a diagram showing an example of the relationship between the coolant temperature Tw and the second required flow rate F(2). The vertical axis in Figure 4 represents the second required flow rate F(2). The horizontal axis in Figure 4 represents the coolant temperature Tw. LN3 in Figure 4 shows the change in the reference value of the second required flow rate F(2) in response to the change in coolant temperature Tw. LN4 in Figure 4 shows the change in the set value of the second required flow rate F(2) in response to the change in coolant temperature Tw.

[0033] As shown in LN3 of Figure 4, the reference value of the second required flow rate F(2) is set to increase monotonically and nonlinearly in response to the increase in the coolant temperature Tw. The ECU 100 may set the second required flow rate F(2) based on the reference value of the second required flow rate F(2), or it may set the second required flow rate F(2) based on the set value of the second required flow rate F(2) set as shown in LN4 of Figure 4 by stepwise changing the second required flow rate F(2) in response to the change in the coolant temperature Tw based on the reference value shown in LN3 of Figure 4. The process then proceeds to S108.

[0034] In S108, the ECU100 determines whether the first requested flow rate F(1) is greater than the second requested flow rate F(2). If it is determined that the first requested flow rate F(1) is greater than the second requested flow rate F(2) (YES in S108), the process moves to S110.

[0035] In S110, the ECU100 sets the first requested flow rate F(1) as the requested amount Fr. The process then moves to S114. If it is determined that the first requested flow rate F(1) is less than or equal to the second requested flow rate F(2) (NO in S10), the process moves to S112.

[0036] In S112, the ECU100 sets the second requested flow rate F(2) as the requested amount Fr. The process then moves to S114.

[0037] In S114, the ECU100 calculates the output Pw of the water pump 30 from the coolant temperature Tw, the required amount Fr, and the map. For example, the ECU100 calculates the output Pw of the water pump 30 from the coolant temperature Tw and the required amount Fr using the map shown in Figure 5.

[0038] Figure 5 is a table illustrating an example of the relationship between coolant temperature Tw, required amount Fr, and the output Pw of the water pump 30. In Figure 5, coolant temperatures from 8°C to 31°C are shown in 1°C increments along the column direction as part of the coolant temperature Tw. Furthermore, in Figure 5, the output of the water pump 30 from 35% to 40% in 1% increments along the row direction as part of the output Pw. Then, the required amount Fr corresponding to the coolant temperature Tw and output Pw is shown at the position corresponding to each row and column in Figure 5. The ECU 100 identifies the corresponding output Pw of the water pump 30 from the coolant temperature Tw, required amount Fr, and the map shown in Figure 5. The process then proceeds to S116.

[0039] In S116, the ECU 100 determines whether or not there is an upper limit guard request. Specifically, the ECU 100 determines that there is an upper limit guard request when vehicle 1 is in a predetermined vehicle state. The predetermined vehicle state includes, for example, a state in which it is required that the water pump 30 be driven with low noise, or a state in which it is required that the water pump 30 be driven in a way that protects its components. For example, the ECU 100 may determine that there is an upper limit guard request if the current time is within a predetermined time period, if the position of vehicle 1 is within a predetermined range, or if a predetermined control mode such as silent mode is selected. If it is determined that there is an upper limit guard request (YES in S116), the process moves to S118.

[0040] In S118, the ECU100 determines whether the output Pw is less than or equal to the upper limit guard value Pwg. The upper limit guard value Pwg is a predetermined value that is determined through experiments or other means. If it is determined that the output Pw is less than or equal to the upper limit guard value Pwg (YES in S118), the process moves to S120. In addition, if it is determined that there is no upper limit guard request (NO in S116), the process also moves to S120.

[0041] In S120, the ECU100 sends the calculated output Pw of the water pump 30 as a drive command to the water pump 30. This process then ends. If it is determined that the output Pw is greater than the upper limit guard value Pwg (NO in S118), the process moves to S122.

[0042] In step S122, the ECU100 sends the upper limit guard value Pwg as a drive command to the water pump 30. This process then terminates.

[0043] The operation of the ECU100 based on the structure and flowchart described above will be explained.

[0044] For example, while vehicle 1 is in operation, the coolant temperature Tw is acquired (S100), and the oil temperature To of the transmission 40 is also acquired (S102). The first required flow rate F(1) is calculated from the acquired oil temperature To and the relationship between the oil temperature To shown in LN1 of Figure 3 and the reference value of the first required flow rate F(1) (S104). Furthermore, the second required flow rate F(2) is calculated from the acquired coolant temperature Tw and the relationship between the coolant temperature Tw shown in LN3 of Figure 4 and the reference value of the second required flow rate F(2) (S106).

[0045] If the oil temperature To in the transmission 40 rises and it is determined that the first required flow rate F(1) is greater than the second required flow rate F(2) (YES in S108), the first required flow rate F(1) is set as the required amount Fr (S110), and the output Pw of the water pump 30 is calculated using the map shown in Figure 5, which shows the relationship between the coolant temperature Tw, the required amount Fr, and the output Pw of the water pump 30 (S114).

[0046] Furthermore, if the cooling water temperature Tw rises due to an increase in the operating amount of the inverter 10 and it is determined that the first required flow rate F(1) is less than or equal to the second required flow rate F(2) (NO in S108), the second required flow rate F(2) is set as the required amount Fr (S110), and the output Pw of the water pump 30 is calculated using the map shown in Figure 5, which shows the relationship between the cooling water temperature Tw, the required amount Fr, and the output Pw of the water pump 30 (S114).

[0047] If it is determined that there is an upper limit guard request (YES in S116), and the output Pw is less than or equal to the upper limit guard value Pwg (YES in S118), the calculated output Pw of the water pump 30 is sent to the water pump 30 as a drive command (S120). On the other hand, if the output Pw exceeds the upper limit guard value Pwg (NO in S118), the upper limit guard value Pwg is sent to the water pump 30 as a drive command (S122).

[0048] As described above, according to the vehicle 1 of this embodiment, when the first required flow rate F(1) is greater than the second required flow rate F(2), the output Pw of the water pump 30 is controlled using the first required flow rate F(1), so the hydraulic fluid of the transmission 40 can be effectively cooled. Furthermore, when the first required flow rate F(1) is less than or equal to the second required flow rate F(2), the output Pw of the water pump 30 is controlled using the second required flow rate F(2), so the inverter 10 can be effectively cooled. In this way, it is possible to suppress excessive operation of the water pump 30. Therefore, it is possible to provide a vehicle that appropriately operates a pump that circulates refrigerant to multiple heat sources.

[0049] The following describes some variations. In the above-described embodiment, we explained as an example the case where the upper limit guard value Pwg is a predetermined value when an upper limit guard request is made. However, for example, the upper limit guard value Pwg may be a value set using the coolant temperature Tw.

[0050] Figure 6 is a diagram illustrating an example of how to set the upper limit guard value Pwg. In Figure 6 (A) and (B), the vertical axis represents the output Pw. In Figure 6 (A) and (B), the horizontal axis represents the coolant temperature Tw. In Figure 6 (A), LN5 shows an example of how the upper limit guard value Pwg changes in response to a change in coolant temperature Tw, with the aim of suppressing the increase in noise and vibration. In Figure 6 (B), LN6 shows an example of how the upper limit guard value Pwg changes in response to a change in coolant temperature Tw, with the aim of protecting components.

[0051] Figure 6(A) LN5 shows that when the cooling water temperature Tw is higher than temperature Tw(0) and lower than Tw(1), the upper limit guard value Pwg is set to Pwg(0), and when it is lower than temperature Tw(0) or higher than temperature Tw(1), the upper limit guard value Pwg is set to Pwg(1) (>Pwg(0)).

[0052] Similarly, in LN6 in (B) of FIG. 6, when the cooling water temperature Tw is lower than temperature Tw(2), Pw(4) is set as the upper limit guard value Pwg; when the cooling water temperature Tw is higher than temperature Tw(2) and lower than temperature Tw(3), Pwg(3) (<Pwg(4)) is set as the upper limit guard value Pwg; and when the cooling water temperature Tw is higher than temperature Tw(3), Pwg(2) (<Pwg(3)) is set as the upper limit guard value Pwg.

[0053] For example, the ECU 100 can suppress an increase in noise and vibration by setting the upper limit value Pwg using the map shown in (A) of FIG. 6. Alternatively, the ECU 100 can realize component protection by setting the upper limit value Pwg using, for example, the map shown in (B) of FIG. 6.

[0054] Furthermore, in the above-described embodiment, the case where the second required flow rate F(2) is calculated using the cooling water temperature Tw has been described as an example, but the second required flow rate F(2) may be calculated using, for example, the cooling water temperature at the outlet of the refrigerant passage 7 provided in the inverter 10.

[0055] Furthermore, in the above-described embodiment, the case where the first required flow rate F(1) is calculated using the oil temperature To has been described as an example, but the first required flow rate F(1) may be calculated using, for example, the rotation amount of any rotating shaft in the transmission 40, the gear stage selected in the transmission 40, or the like.

[0056] It should be noted that all or part of the above-described modified examples may be appropriately combined for implementation. It should be considered that the embodiment disclosed this time is illustrative in all respects and is not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims. [Description of Reference Signs]

[0057] 1 Vehicle. 5 Cooling system, 6, 7, 8 Refrigerant passages, 10 Inverter, 20 Oil cooler, 30 Water pump, 32 Reserve tank, 40 Transmission, 50 Radiator, 60 Power transmission gear, 62 Drive wheels, 100 ECU, 102 Coolant temperature sensor, 104 Oil temperature sensor.

Claims

1. The transmission installed in the vehicle, Inverter and A cooling device for cooling the hydraulic fluid of the transmission and the inverter, The system includes a control device that controls the operation of the cooling device, The cooling device comprises an oil cooler through which the hydraulic fluid of the transmission flows, a refrigerant passage through which the inverter flows, and a pump for circulating the refrigerant between the oil cooler and the refrigerant passage. The control device controls the output of the pump using the higher of a first required flow rate, which is the flow rate of the refrigerant required in the oil cooler, and a second required flow rate, which is the flow rate of the refrigerant required in the refrigerant passage.

2. The vehicle according to claim 1, wherein the control device controls the output of the pump using the upper limit value if the output of the pump is greater than the upper limit value set when the vehicle is in a predetermined vehicle state.

3. The vehicle according to claim 1 or 2, wherein the control device sets the first required flow rate using the temperature of the hydraulic fluid and sets the second required flow rate using the temperature of the refrigerant.

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