JP2017114298A - Cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration of energy efficiency of a cooling system.SOLUTION: A cooling system includes; a first circuit 10 for cooling an engine 1; a second circuit 20 for cooling an electric motor 2; valves V, V, V; and a control section 50. In the first circuit 10, a first refrigerant pressure-fed by an engine-driven first pump Pis caused to flow. In the second circuit 20. a second refrigerant pressure-fed by an electric second pump Pis caused to flow. The valves V, V, Vare provided in communication passages 30, 31, 32 for communicating the first circuit 10 and the second circuit 20 with each other. When a predetermined condition including a situation where the first pump Pis driven by the engine 1 is satisfied, the control device 50 suppresses output of the second pump Pwhile opening the valves V, V, V.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a system for cooling an engine and an electric motor in a hybrid vehicle.

  In a hybrid vehicle equipped with an engine and an electric motor as a travel drive source, a cooling system is known that is individually equipped with a cooling system for cooling the engine and the electric motor. The engine cooling system is provided with an engine cooling circuit through which refrigerant pumped by an engine-driven mechanical pump circulates, and the motor cooling circuit through which the refrigerant pumped by electric pump is circulated in the electric motor cooling system Is provided.

The engine cooling system has a higher heat generation capacity than the electric motor cooling system, so the cooling capacity is increased, and a large amount of refrigerant is pumped by the pump, and the heat absorbed by the refrigerant is large. There is a tendency.
In view of this, a technique has been developed in which heat absorbed by the refrigerant in the engine cooling system is used in the cooling system of the electric motor. For example, in order to heat the cooling system of an electric motor in a cold environment, an on-off valve is provided in the flow path connecting the motor cooling circuit and the engine cooling circuit, and then the on-off valve is opened to provide two cooling circuits. A technique for communicating the above has been studied (see Patent Documents 1 and 2).

JP 2013-073533 Japanese Patent No. 4958637

In the cooling system to which the two cooling circuits as described above are connected, the cooling capacity of the engine cooling system is higher than the cooling system of the electric motor, so that the mechanical pump has a higher output than the electric pump. Is used.
However, if the temperature of the refrigerant decreases and the viscosity increases, the pumping load of the pump increases due to an increase in the viscous resistance, leading to a decrease in energy efficiency. In this case, the energy efficiency of the electric pump having a lower output than the mechanical pump is likely to decrease. In addition, if the engine is not started in the first place, the mechanical pump cannot be driven, and even if two cooling circuits are connected, refrigerant is not pumped by the engine cooling circuit. There is also a risk of increasing energy efficiency.

  The cooling system of the present case has been created in view of the above-described problems, and has an object to suppress a decrease in energy efficiency. Note that the present invention is not limited to this purpose, and is an operation and effect derived from each configuration shown in “Mode for Carrying Out the Invention” to be described later. It can be positioned as another purpose.

(1) The cooling system disclosed herein includes a first circuit for cooling the engine, a second circuit for cooling the electric motor, a valve, and a control unit.
A first refrigerant that is pumped by a first pump flows through the first circuit. The first pump is driven by the engine.
A second refrigerant pumped by an electric second pump flows through the second circuit.
The valve is interposed in a communication path that connects the first circuit and the second circuit.
The control unit suppresses the output of the second pump while opening the valve when a predetermined condition is satisfied including that the engine is driving the first pump.
The first pump has a higher output than the second pump. Further, when the valve is opened, the first circuit and the second circuit are communicated, and when the valve is closed, the communication between the first circuit and the second circuit is blocked.

(2) It is preferable that the predetermined condition includes that the temperature of the first refrigerant is lower than an upper limit temperature allowed in the second circuit.
The temperature of the first refrigerant varies greatly depending on the amount of heat generated by the engine, and may be high, for example, to the extent that it exceeds the operating upper limit temperature of the electric motor. However, if the valve is opened in such a situation, there is a risk that the stable operation of the electric motor cannot be guaranteed. Therefore, it is preferable that the control unit opens the valve on condition that the first refrigerant is not excessively hot.
If the temperature of the first refrigerant is equal to or higher than the upper limit temperature allowed in the second circuit, the control unit preferably closes the valve and maintains the output of the second pump.

(3) It is preferable that the control unit increases the output suppression amount of the second pump as the temperature of the second refrigerant is lower when the predetermined condition is satisfied. The first refrigerant and the second refrigerant increase in viscosity as the temperature decreases.
(4) Moreover, it is preferable that the said control part enlarges the output suppression amount of said 2nd pump, so that the temperature of said 1st refrigerant | coolant is low, when the said predetermined conditions are satisfied.
(5) It is preferable that the predetermined condition includes that the temperature of the first refrigerant is higher than the temperature of the second refrigerant.

(6) Preferably, the first circuit is provided with a first radiator that radiates heat of the first refrigerant. Further, it is preferable that the communication path is provided with a first series path that communicates the second circuit with the downstream side of the engine in the first circuit and the upstream side of the first radiator. In this case, it is preferable that the valve has a first valve interposed in the first series passage.
(7) Moreover, it is preferable that the said 2nd circuit is provided with the 2nd radiator which thermally radiates said 2nd refrigerant | coolant. Furthermore, it is preferable that the communication path is provided with a second communication path that connects the first circuit with the upstream side of the second radiator in the second circuit. In this case, it is preferable that the valve has a second valve interposed in the second communication path.

(8) Preferably, when the second pump fails while the engine is stopped, the control unit starts the engine and opens the valve.
(9) It is preferable that the control unit increases the output suppression amount of the second pump as the output of the first pump increases when the predetermined condition is satisfied.

  According to the cooling system of the present invention, when the first pump is driven, the valve is opened to allow the first circuit and the second circuit to communicate with each other, and the output of the electric second pump is suppressed. At least a part of the pumping load of the second refrigerant can be carried by the engine-driven first pump, and a reduction in energy efficiency can be suppressed.

It is a schematic diagram which shows a cooling system, and the white arrow is the distribution direction of a refrigerant | coolant. It is a graph which illustrates correspondence with refrigerant temperature and a correction coefficient for controlling an output of an electric pump. It is a graph which illustrates the correspondence between the magnitude of the output of the mechanical pump and the correction coefficient for suppressing the output of the electric pump. It is a flowchart which illustrates the procedure of control in a cooling system. It is a flowchart which illustrates the procedure of the output suppression control of FIG.

  A cooling system as an embodiment will be described with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment. Each configuration of the present embodiment can be implemented with various modifications without departing from the spirit thereof. Further, they can be selected as necessary, or can be appropriately combined.

The cooling system of the present embodiment is installed in a hybrid vehicle equipped with an engine and an electric motor as a travel drive source. In a hybrid vehicle, an engine and an electric motor are selectively used according to the traveling state. For example, an electric motor or an engine is used alone, or an electric motor and an engine are used in combination.
In this cooling system, each of the engine and the electric motor is to be cooled, and these cooling objects are cooled by the refrigerant. In the present embodiment, upstream and downstream are determined based on the refrigerant flow direction.

[1. Construction]
First, the basic structure of the cooling system will be described with reference to FIG. Hereinafter, two cooling structures for cooling each of the engine 1 and the electric motor 2 and a structure for connecting these cooling structures will be described in this order.
[1-1. Cooling structure]
In the cooling system, a cooling system for the engine 1 and a cooling system for the electric motor 2 are individually provided. An engine cooling circuit (first circuit) 10 for cooling the engine 1 is provided in the cooling system of the engine 1, and a motor cooling circuit (second circuit) 20 for cooling the electric motor 2 is provided in the cooling system of the electric motor 2. Is provided. Further, the same coolant is used for the engine refrigerant (first refrigerant) flowing through the engine cooling circuit 10 and the motor refrigerant (second refrigerant) flowing through the motor cooling circuit 20. These refrigerants have the property that the viscosity increases as the temperature decreases.

The engine cooling circuit 10 includes an engine 1 to be cooled, a mechanical pump (first pump) P ₁ driven by the engine 1, and an engine radiator (first radiator) 12 that radiates engine refrigerant. The
The engine cooling circuit 10 is provided with an upstream circuit 101 through which engine refrigerant flows from the engine radiator 12 to the engine 1 and a downstream circuit 102 through which engine refrigerant flows from the engine 1 to the engine radiator 12.

The engine 1 is an internal combustion engine that outputs a driving force by heat energy obtained by burning fuel. As the engine refrigerant circulates inside the engine 1, the operating heat of the engine 1 is absorbed by the engine refrigerant and cooled. The driving force of the engine 1 is output to the mechanical pump P ₁ in addition to the wheels.

The mechanical pump P ₁ is an engine refrigerant pressure feeder that uses the driving force of the engine 1 as a power source. The mechanical pump P ₁ operates in conjunction with the engine P1. That is, when the engine 1 is operated, the mechanical pump P ₁ is also operated, and when the engine 1 is stopped, the operation of the mechanical pump P ₁ is also stopped.
The engine radiator 12 is a radiator that cools engine refrigerant by exchanging heat with outside air. As the engine refrigerant flows through the engine radiator 12, the engine refrigerant radiates heat by the outside air.

The motor cooling circuit 20 includes an electric motor (shown as “M / G” <Motor Generator>) 2 in FIG. 1 as an object to be cooled, an electric motor 2 and a battery for driving (shown as “BAT” in FIG. 1). ) 6 and other components such as an inverter (shown as “INV” in FIG. 1) 3 and an in-vehicle charger (shown as “OBC” <On Board Charger> in FIG. 1) 4 are interposed. Further, the motor cooling circuit 20 is provided with an electric pump (second pump) P ₂ driven by the auxiliary battery 9 and a motor radiator (second radiator) 22 for radiating the motor refrigerant.

The motor cooling circuit 20 is provided with an upstream circuit 201 through which motor refrigerant flows from the motor radiator 22 to the electric motor 2 and a downstream circuit 202 through which motor refrigerant flows from the electric motor 2 to the motor radiator 22. .
The electric motor 2 is a motor generator that has both a function of powering during traveling and a function of regenerating during braking. The inverter 3 connected to the electric motor 2 is also referred to as a DC-AC inverter, and is a converter that converts current from direct current to alternating current or converts current from alternating current to direct current. When the electric motor 2 is powered, the AC frequency and the AC voltage are controlled by, for example, an IGBT (Insulated Gate Bipolar Transistor) module built in the inverter 3, and when the electric motor 2 is regenerated, the generated power is converted into DC power and travels. The driving battery 6 is charged.

The on-vehicle charger 4 is also referred to as an AC-DC inverter, and is a converter that converts current from alternating current to direct current when charging the driving battery 6 using an external charging facility such as a charging station or a household outlet. is there. For example, several hundreds of volts of AC power supplied from an external power supply device is converted into several hundreds of volts of DC power, and the travel drive battery 6 is charged.
Since the electric motor 2, the inverter 3 and the on-vehicle charger 4 generate heat during operation, the electric motor 2, the inverter 3 and the in-vehicle charger 4 are cooled so as to continue to operate within a predetermined use temperature range.

The electric pump P ₂ is a motor refrigerant pump that uses the power of the auxiliary battery 9 as a power source. The operating state of the electric pump P ₂ is controlled independently from the operating state of the engine 1. For example, the electric pump P ₂ can be operated while the engine 1 is stopped, and the operation of the electric pump P ₂ can be stopped while the engine 1 is operating.
The motor radiator 22 is a radiator that cools the motor refrigerant by exchanging heat with the outside air, like the engine radiator 12 described above. As the motor refrigerant flows through the motor radiator 22, the motor refrigerant radiates heat by the outside air.

Next, the cooling system of the engine 1 and the cooling system of the electric motor 2 will be compared and described.
The amount of heat generated during operation of the engine 1 is greater than the amount of heat generated during operation of the electric motor 2, the inverter 3, and the in-vehicle charger 4. Therefore, the cooling capacity of the engine 1 is higher than that of the electric motor 2. Specifically, the engine coolant amount (for example, 100 to 200 liters) of the engine cooling circuit 10 is larger than the motor coolant amount (for example, 5 to 10 liters) of the motor cooling circuit 20. Further, the mechanical pump P ₁ that pumps the engine refrigerant has a higher output than the electric pump P ₂ that pumps the motor refrigerant.

In addition, the cooling target of the motor cooling circuit 20 (the electric motor 2, the inverter 3, and the in-vehicle charger 4) has a lower allowable upper limit temperature (heat resistance) than the cooling target of the engine cooling circuit 10 (engine 1). . For example, the upper limit temperature allowed in the engine cooling circuit 10 is about 120 ° C., and the upper limit temperature allowed in the motor cooling circuit 20 is about 60 ° C. Therefore, the temperature of the motor refrigerant in the motor cooling circuit 20 (hereinafter referred to as “motor refrigerant temperature”) T _M is higher than the temperature of the engine refrigerant in the engine cooling circuit 10 (hereinafter referred to as “engine refrigerant temperature”) T _E. It is exclusively cold.

[1-2. Communication structure]
Next, a structure for connecting the two cooling circuits 10 and 20 described above will be described. Here, as the connection structure, three communication passages 30, 31, 32 are provided.
The communication paths 30, 31, and 32 are refrigerant flow paths that allow the engine cooling circuit 10 and the motor cooling circuit 20 to communicate with each other.
In these communication passages 30, 31, and 32, one inflow communication passage 30 through which engine refrigerant flows from the engine cooling circuit 10 to the motor cooling circuit 20, and motor refrigerant from the motor cooling circuit 20 to the engine cooling circuit 10 circulates. Are roughly divided into two outflow communication passages 31 and 32.

The inflow communication path 30 allows the downstream circuit 102 of the engine cooling circuit 10 and the upstream circuit 201 of the motor cooling circuit 20 to communicate with each other. That is, the first connection portions S ₁ to the upstream end of the inflow communication path 30 on the downstream side circuit 102 of the engine cooling circuit 10 is connected, the flow passage which is branched to the three-way intersection shape is formed. Similarly, the second connecting point S ₂ of the downstream end of the inlet communicating passage 30 on the upstream side circuit 201 of the motor cooling circuit 20 is connected, the flow passage which is branched to the three-way intersection shape is formed.

One of the two outflow communication passages 31 and 32 is a first outflow communication passage 31 that connects the downstream circuit 102 in the engine cooling circuit 10 and the upstream circuit 201 in the motor cooling circuit 20, and the other is the motor cooling. This is a second outflow communication path 32 that communicates the downstream circuit 202 of the circuit 20 and the downstream circuit 102 of the engine cooling circuit 10.
The upstream end portion of the first outflow communication passage 31 is connected to the third connection location S ₃ upstream of the second connection location S ₂ to which the inflow communication passage 30 is connected in the upstream circuit 201 of the motor cooling circuit 20. Is done. Further, the downstream end portion of the first outflow communication passage 31 is a fourth connection location S ₄ downstream of the first connection location S ₁ to which the inflow communication passage 30 is connected in the downstream circuit 102 of the engine cooling circuit 10. Connected to.

The upstream end portion of the second outflow communication passage 32 is the fifth connection point S downstream of all the cooling objects (electric motor 2, inverter 3, on-vehicle charger 4) in the downstream circuit 202 of the motor cooling circuit 20. Connected to ₅ . Further, the downstream end portion of the second outflow communication passage 32 is a sixth connection location S ₆ downstream of the first connection location S ₁ to which the inflow communication passage 30 is connected in the downstream circuit 102 of the engine cooling circuit 10. Connected to. Here, the downstream circuit 102 of the engine cooling circuit 10, the sixth connection point S ₆ is disposed on the downstream side of the fourth connection point S _4.
In the third to sixth connection locations S _{3 to} S ₆ , a flow path branched into a three-way shape is formed in the same manner as the first and second connection locations S ₁ and S ₂ .

[2. control]
Next, control related to the circulation of the refrigerant in the above-described cooling structure will be described. This control is performed by the control device (control unit) 50.
[2-1. Connection device]
First, a device connected to the control device 50 will be described.
A device that transmits information to the control device 50 is connected to the input side of the control device 50, and a control target of the control device 50 is connected to the output side of the control device 50.

Specifically, the engine coolant temperature sensor (first sensor) 41, the motor coolant temperature sensor (second sensor) 42, the mechanical pump P ₁ and the electric pump P ₂ described above, The engine 1 and four valves V _{1 to} V ₄ are connected.
The engine refrigerant temperature sensor 41, the motor refrigerant temperature sensor 42, and the mechanical pump P ₁ are connected to the input side of the control device 50, and the valves V _{1 to} V ₄ are connected to the output side of the control device 50. Further, the electric pump P ₂ and the engine 1 are connected to the input side and the output side of the control device 50, respectively.

Engine coolant temperature sensor 41 is a detector for detecting an engine coolant temperature T _E. Similarly, the motor coolant temperature sensor 42 is a detector for detecting the motor coolant temperature T _M. Here, an engine refrigerant temperature sensor 41 is provided between the engine 1 and the first connection location S ₁ in the downstream circuit 102 of the engine cooling circuit 10, and the engine refrigerant temperature of the downstream circuit 102 is determined by the engine refrigerant temperature sensor 41. T _E is detected. Further, in the upstream circuit 201 of the motor cooling circuit 20, a motor refrigerant temperature sensor 42 is provided between the second connection location S ₂ and the electric motor 2, and the motor refrigerant temperature sensor 42 detects the motor refrigerant temperature of the upstream circuit 201. T _M is detected. Information on the engine refrigerant temperature T _E and the motor refrigerant temperature T _M is transmitted to the control device 50.

From the mechanical pump P ₁ , information regarding the magnitude of its output is transmitted to the control device 50. The information on the magnitude of the output is information about the pumping quantity and pumping pressure of the mechanical pump P _1. This information includes pump rotation speed information and operating current information that vary depending on the output level of the mechanical pump P ₁ .
From the electric pump P ₂ , information about its own failure is transmitted to the control device 50. The information on the failure is information indicating whether the electric pump P ₂ is faulty. Examples of this information include pump rotation speed information and operating current information.
From the engine 1, information about its own operation is transmitted to the control device 50. The information regarding the operation is information indicating whether or not the engine 1 is operating. This information includes crank rotation speed information.

The valves V _{1 to} V ₄ are interposed in the refrigerant flow path. Specifically, the first valve V ₁ is interposed in the inflow communication passage 30, the second valve V ₂ is interposed in the first outflow communication passage 31, and the third valve (second valve) V ₃ is the second. The fourth valve V ₄ is interposed downstream of the fifth connection point S ₅ in the downstream circuit 202 of the motor cooling circuit 20.
These valves V _{1 to} V ₄ are electromagnetic on-off valves that are controlled to open and close by the control device 50. The first valve V ₁ , the second valve V ₂ , and the third valve V ₃ are normally closed valves that maintain a closed state when not energized (during non-control). On the other hand, the fourth valve V ₄ is a normally open valve that maintains an open state when not energized (not controlled).

[2-2. Control device]
Next, the control device 50 will be described. The control device 50 includes an electronic device (ECU, electronic device) in which a microprocessor such as a CPU (Central Processing Unit) and an MPU (Micro Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and a nonvolatile memory are integrated. Control device). The processor here is, for example, a processing device (processor) including a control unit (control circuit), an arithmetic unit (arithmetic circuit), a cache memory (register), and the like. The ROM, RAM, and nonvolatile memory are memory devices that store programs and working data. The contents of the control performed by the control device 50 are recorded in the ROM, RAM, nonvolatile memory, and removable medium as firmware and application programs. When the program is executed, the contents of the program are expanded in the memory space in the RAM and executed by the processor.

The control device 50 has a function of outputting various control commands to a control target according to success or failure of various control conditions.
As an element for performing various controls, the control device 50 determines various control conditions based on the determination unit 510 that determines various control conditions and the success or failure of the control conditions determined by the determination unit 510. And a command unit 520 for performing the operation. The command unit 520 includes a valve command unit 530 that commands opening and closing of the valves V _{1 to} V ₄ , a pump command unit 540 that commands the operating state of the electric pump P ₂ , and an engine that commands the operating state of the engine 1. A command unit 550 is provided. Further, the pump command unit 540 is provided with an output calculation unit 541 that calculates the magnitude of the output of the electric pump P ₂ .

The determination unit 510, the command unit 520, the valve command unit 530, the pump command unit 540, the output calculation unit 541, and the engine command unit 550 indicate some functions of a program executed by the control device 50. It shall be realized by software. However, some or all of the functions may be realized by hardware (electronic control circuit), or may be realized by using software and hardware in combination.
Here, the correspondence between the success or failure of various control conditions determined by the determination unit 510 and the various controls whose control contents are commanded by the command unit 520 is shown in Table 1 below.

<Control conditions>
Hereinafter, each of the control conditions shown in Table 1 will be described in the order of engine operating conditions, fail conditions, and refrigerant temperature conditions (predetermined conditions).
The engine operating condition is a condition for determining whether or not the engine 1 is operating. Therefore, the engine operating condition is satisfied when the engine 1 is operating, and is not satisfied when the engine 1 is stopped. Since the operation of the mechanical pump P ₁ is linked to the engine 1, the engine operating condition can be said to be a condition for determining whether or not the mechanical pump P ₁ is operating.

The normal conditions for starting the stopped engine 1 include the following conditions A1 to A3 (OR conditions).
Condition A1: The environmental temperature is equal to or lower than the predetermined environmental temperature Condition A2: The capacity (SOC: State Of Charge, charging rate) of the driving battery 6 is
Condition A3: The required output torque is greater than the predetermined torque

  The environmental temperature of condition A1 is the temperature of the environment to which the cooling system is exposed. As this environmental temperature, for example, the outside air temperature or the refrigerant temperature can be used. In addition, as the predetermined environmental temperature, a lower limit temperature (for example, −10 ° C.) at which stable operation of the electric motor 2 and the traveling drive battery 6 is guaranteed is set. In addition, the predetermined capacity of the condition A2 is set to a lower limit capacity (for example, 30%) at which it can be considered that the capacity of the battery 6 for driving and driving is sufficiently remaining, and the predetermined torque of the condition A3 includes the electric motor 2 The maximum output torque is set.

Fail condition is a condition for determining whether the electric pump P ₂ is faulty. Therefore, the fail condition, electric pump P ₂ is satisfied if the failure, the electric pump P ₂ is not satisfied unless a failure.

The refrigerant temperature condition is a temperature condition for appropriately flowing the engine refrigerant of the engine cooling circuit 10 into the motor cooling circuit 20. In the determination of the refrigerant temperature condition, the first condition and the second condition are determined after determining whether the basic condition is successful.
The basic conditions include the following conditions B1 and B2 (AND conditions).
Condition B1: The engine refrigerant temperature T _E is lower than the allowable upper limit temperature T ₀ (T _E <T ₀ ) Condition B2: The engine refrigerant temperature T _E is higher than the motor refrigerant temperature T _M (T _M <T _E )
Is

The allowable upper limit temperature T ₀ of the condition B1 is an upper limit temperature (for example, 60 ° C.) at which stable operation of the electric motor 2, the inverter 3, and the in-vehicle charger 4 is guaranteed. That is, the upper limit temperature allowed in the motor cooling circuit 20 is set in advance as the allowable upper limit temperature T ₀ .
The first condition is that the motor refrigerant temperature T _M is equal to or lower than the first predetermined temperature T ₁ (T _M ≦ T ₁ ). On the other hand, the second condition is that the motor refrigerant temperature T _M is higher than the first predetermined temperature T ₁ (T _M > T ₁ ). The first predetermined temperature T ₁ is set in advance as an upper limit temperature (for example, −10 ° C.) at which the motor refrigerant can be regarded as having a high viscosity. Note that success or failure is exclusively determined under the first condition and the second condition.

  As shown in Table 1 above, when it is determined that the failure condition is not satisfied and the basic condition of the refrigerant temperature condition is not satisfied, normal control is performed. Further, when it is determined that the engine operating condition is not satisfied and the fall condition is satisfied, fail control is performed. Further, when it is determined that the engine operating condition is satisfied and the basic condition of the refrigerant temperature condition is satisfied, output suppression control is performed. In this output suppression control, the first control is performed when the basic condition is satisfied and the first condition is determined to be satisfied, and the second control is performed when the second condition is determined to be satisfied.

<Control details>
Next, with reference to Table 2 below, various controls for which control contents are commanded from the command unit 520 will be described in the order of normal control, fail control, and output suppression control.

The normal control is control in which the communication between the engine cooling circuit 10 and the motor cooling circuit 20 is cut off and the refrigerant is circulated independently of each other. In this normal control, the first valve V ₁ , the second valve V _2, and the third valve V ₃ provided in each of all the communication passages 30, 31, 32 are closed, and the first valve provided in the motor cooling circuit 20 is closed. to open four-valve V _4. By controlling the opening / closing pattern of the valves V _{1 to} V _{4 in} this way, the engine refrigerant circulates only in the engine cooling circuit 10 and the motor refrigerant circulates only in the motor cooling circuit 20. The electric pump P ₂ is not particularly controlled and operates as usual.
Here, since the opening / closing pattern of the valves V _{1 to} V ₄ at the time of de-energization is the same as the opening / closing pattern of the valves V _{1 to} V ₄ in the normal control, the engine cooling circuit 10 and the motor even if no control command is given. The refrigerant flows independently through the cooling circuit 20. Therefore, in the cooling system of this embodiment, “execution of normal control” may be read as “no control”.

The fail control is a control for circulating the motor refrigerant of the motor cooling circuit 20 using the mechanical pump P ₁ when the electric pump P ₂ fails. In this fail control, if the engine 1 is not operating, the engine 1 is forcibly started, the first valve V ₁ , the second valve V ₂ and the fourth valve V ₄ are opened, and the third valve V ₃ is closed. Let By controlling the opening / closing pattern of the valves V _{1 to} V _{4 in} this way, the engine refrigerant flowing from the engine cooling circuit 10 via the inflow communication path 30 is transferred to the motor via the electric motor 2, the inverter 3, and the on-vehicle charger 4. Cooled by the radiator 22, returned to the engine cooling circuit 10 from the first outflow communication passage 31, and cooled by the engine radiator 12.

The output suppression control is a control for suppressing the output of the electric pump P ₂ after causing the mechanical pump P ₁ to bear the pressure of the motor refrigerant in the motor cooling circuit 20. Therefore, the output suppression control, suppression of the output to the electric pump P ₂ is commanded. The output to the electric pump P ₂ commanded in this way is calculated by the output calculation unit 541.

Here, the output of the electric pump P ₂ calculated by the output calculation unit 541 will be described. The output calculation unit 541 calculates the output O _E of the electric pump P ₂ based on predetermined parameters such as the motor refrigerant temperature T _M , the engine refrigerant temperature T _E , and the output O _M of the mechanical pump P ₁ .
For example, as shown in FIG. 2, by multiplying the rated output O _E1 of the electric pump P _{2 by} a correction coefficient α that decreases as the motor refrigerant temperature T _M decreases, the output O _E of the electric pump P ₂ is obtained. (= Α · O _E1 ) is calculated.

In FIG. 2, if the motor refrigerant temperature T _M is equal to or lower than the first predetermined temperature T ₁ described above, the correction coefficient α is set to “0 (zero)”, and the electric pump P ₂ is stopped. On the other hand, if the motor refrigerant temperature T _M is higher than the second predetermined temperature T ₂ , the correction coefficient α is set to “1”, so the output O _E (= O _E1 ) of the electric pump P ₂ is not suppressed. This second predetermined temperature T ₂ is set in advance as a lower limit temperature (for example, 10 ° C.) at which the motor refrigerant can be regarded as having a low viscosity. A motor refrigerant having a temperature higher than the first predetermined temperature T _{1 and not} higher than the second predetermined temperature T ₂ can be regarded as a medium viscosity.
Alternatively, as shown in parentheses in FIG. 2, the β becomes smaller the correction coefficient as the engine coolant temperature T _E is lower, by multiplying the output O _E1 of the electric pump P _2, the output of the electric pump P ₂ O _E (= β · O _E1 ) may be calculated.

In addition, as shown in FIG. 3, by multiplying the rated output O _E1 of the electric pump P _{2 by} a correction coefficient γ that decreases as the output O _M of the mechanical pump P ₁ increases, the electric pump P ₂ The output O _E (= γ · O _E1 ) may be calculated.
In FIG. 3, if the output O _M of the mechanical pump P ₁ is lower than the first predetermined output O _M1 , the correction coefficient γ is set to “1”, and if it is higher than the second predetermined output O _M2 , the correction coefficient γ Is set to “0 (zero)”. The first predetermined output O _M1 is set in advance as an upper limit output that may cause problems such as unstable combustion and stall of the engine 1 when the mechanical pump P ₁ bears a further load. On the other hand, the second predetermined output O _M2 is set in advance as a lower limit output in which the mechanical pump P ₁ has sufficient capacity.

Note that the output O _E of the electric pump P ₂ may be calculated using at least two of the correction coefficients α, β, and γ described above.
The output O _E calculated by the output calculation unit 541 in this way is used as an output command value to the electric pump P ₂ in the output suppression control.

In the first control of the output suppression control, the first condition (T _M ≦ T ₁ ) is satisfied as a control condition. That is, since the correction coefficient α is “0 (zero)”, the electric pump P ₂ is stopped. In the first control, the first valve V ₁ and the third valve V ₃ are opened, and the second valve V ₂ and the fourth valve V ₄ are closed. By controlling the opening / closing pattern of the valves V _{1 to} V _{4 in} this way, the engine refrigerant flowing from the motor cooling circuit 20 via the inflow communication path 30 passes through the electric motor 2, the inverter 3, and the on-vehicle charger 4. It returns to the engine cooling circuit 10 from the second outflow communication passage 32.

In the second control of the output suppression control, the output of the electric pump P ₂ is suppressed. At this time, the output suppression amount of the electric pump P ₂ is controlled to be larger as the motor refrigerant temperature T _M and the engine refrigerant temperature _TE are lower or the output O _M of the mechanical pump P ₁ is higher. In the second control, the first valve V ₁ , the second valve V _2, and the fourth valve V ₄ are opened and the third valve V ₃ is closed as in the fail control. Then, the engine refrigerant flowing from the engine cooling circuit 10 through the inflow communication passage 30 is cooled by the motor radiator 22 through the electric motor 2, the inverter 3, and the on-vehicle charger 4, and from the first outflow communication passage 31 to the engine cooling circuit 10. To reflux. As described above, the control device 50 during the output suppression control opens the first valve V ₁ , the second valve V _2, and the fourth valve V ₄ to allow the engine cooling circuit 10 and the motor cooling circuit 20 to communicate with each other. The output of the electric pump P ₂ is suppressed.

[3. flowchart]
Next, a control flow in the cooling system will be described.
This control flow is repeatedly performed at a predetermined cycle when the vehicle main switch is on. In addition, each step in the flowchart is implemented by each function assigned to the hardware of the control device 50 being operated by software (computer program).

As shown in FIG. 4, first, it is determined whether or not the engine 1 is operating (step A10). That is, the success or failure of the engine operating condition is determined.
If the engine 1 is operating (engine operating conditions are established), it is determined whether or not the engine refrigerant temperature T _E is lower than the allowable upper limit temperature T ₀ (step A20), and the motor refrigerant temperature T _M is determined. towards the engine coolant temperature T _E is determined whether a high temperature (step A30). That is, the success or failure of the basic condition in the refrigerant temperature condition is determined.
Then, the output of the electric pump P ₂ is calculated based on a predetermined parameter (step A40), and execution of output suppression control is commanded (step A50).

As shown in FIG. 5, in the output suppression control, it is determined whether or not the motor refrigerant temperature T _M is equal to or lower than a first predetermined temperature T ₁ (step A52). That is, it is determined whether the first condition of the refrigerant temperature condition is satisfied (whether the second condition is not satisfied).
If the motor refrigerant temperature T _M is equal to or lower than the first predetermined temperature T ₁ (the first condition is satisfied and the second condition is not satisfied), execution of the first control is commanded (step A54), and the motor refrigerant temperature T _M is If the temperature is higher than the predetermined temperature T ₁ (the first condition is not satisfied and the second condition is satisfied), the execution of the second control is commanded (step A56). Then, this control cycle ends (returns).

Further, as shown in FIG. 4, if the engine is stopped (engine operating condition is not satisfied), it determines whether the electric pump P ₂ has failed (step A60). That is, the success or failure of the fail condition is determined. If the electric pump P ₂ is out of order (fail condition is satisfied), the execution of fail control is commanded (step A70). If the electric pump P ₂ is normal (fail condition is not satisfied), the normal control is performed. The execution is commanded (step A80). Then, this control cycle ends (returns).

[4. Action and effect]
Since the cooling system of the present embodiment is configured as described above, the following operations and effects can be obtained.
(1) According to the output suppression control performed in the cooling system, when the engine operating condition is satisfied, that is, when the mechanical pump P ₁ is driven, the first inflow communication passage 30 and the second outflow communication passage 32 are provided. The one valve V ₁ and the third valve V ₃ are opened, or the first valve V ₁ and the second valve V ₂ provided in the inflow communication path 30 and the first outflow communication path 31 are opened, and the engine cooling circuit 10 And the motor cooling circuit 20 are communicated. In addition, since the output of the electric pump P ₂ can be suppressed, at least a part of the motor refrigerant pumping load in the motor cooling circuit 20 can be assigned to the mechanical pump P _1, and a decrease in energy efficiency can be suppressed. .

(2) Further, the control condition of the output suppression control, that is, the refrigerant temperature condition includes that the engine refrigerant temperature T _E is lower than the allowable upper limit temperature T ₀ (condition B1). Therefore, it is possible to avoid overheating of the electric motor 2, the inverter 3, and the in-vehicle charger 4, which are to be cooled, due to the engine refrigerant temperature T _E flowing into the motor cooling circuit 20. Therefore, it is possible to ensure the thermal protection of the object to be cooled and ensure the operational stability.

(3) By the way, the viscosity of the refrigerant increases as the temperature decreases. Due to this increase in viscosity, the pumping load of refrigerant by the pump also increases. Since the electric pump P ₂ has a lower output than the mechanical pump P _{1, the} motor refrigerant pressure-feeding load by the electric pump P ₂ tends to increase. Therefore, in the output suppression control, the output of the electric pump P ₂ that pumps the motor refrigerant whose viscosity increases as the motor refrigerant temperature T _M decreases is suppressed. Therefore, the pumping load of the motor refrigerant by the electric pump P ₂ can be appropriately reduced. Therefore, a decrease in energy efficiency can be reliably suppressed.

For example, if the motor refrigerant temperature T _M is equal to or lower than the first predetermined temperature T ₁ , there is a possibility that high-viscosity motor refrigerant cannot be pumped by the electric pump P ₂ . In this case, the motor refrigerant stays in the motor cooling circuit 20, the motor refrigerant locally overheats only around the cooling target, and there is a possibility that the thermal protection of the cooling target cannot be ensured. Further, it takes an excessive load on the electric pump P _2.

However, in the first control of the output suppression control, if the motor refrigerant temperature T _M is equal to or lower than the first predetermined temperature T ₁ and the motor refrigerant has a high viscosity, the electric pump P ₂ is stopped. Therefore, the pumping load of the electric pump P ₂ can be reduced after the cooling target of the motor cooling circuit 20 is appropriately cooled by pumping the motor refrigerant only by the mechanical pump P ₁ .
Further, if the motor refrigerant temperature T _M is higher than the first predetermined temperature T ₁ , the pumping load of the medium viscosity motor refrigerant by the electric pump P ₂ increases. In this case, the second control of the output suppression control is performed, and the motor refrigerant is pumped by the electric pump P ₂ and the mechanical pump P ₁ whose outputs are suppressed. Therefore, it is possible to suppress an increase in the pumping load of the mechanical pump P ₁ while suppressing an increase in the pumping load of the electric pump P ₂ . Therefore, the electric pump P ₂ and the mechanical pump P ₁ can appropriately share the pressure load.

(4) Similarly, in the output suppression control, if the output of the electric pump P ₂ is Rarere suppressed as the engine coolant temperature T _E is lower, the viscosity of the engine coolant flowing from the engine cooling circuit 10 to the motor cooling circuit 20 rises As a result, the output of the electric pump P ₂ is suppressed. Therefore, a decrease in energy efficiency can be reliably suppressed.

(5) Furthermore, the refrigerant temperature condition includes that the engine refrigerant temperature T _E is higher than the motor refrigerant temperature T _M (condition B2). Therefore, the viscosity reduction of the motor refrigerant in the motor cooling circuit 20 can be promoted by the engine refrigerant temperature T _E flowing into the motor cooling circuit 20. Accordingly, the viscous resistance of the motor coolant reduces the pumping load of the electric pump P ₂ can be reduced.
On the contrary, since the motor refrigerant having a temperature lower than that of the engine refrigerant flows into the engine cooling circuit 10, the cooling of the engine 1 can be promoted.

(6) In the output suppression control, the inflow communication path connected to the first connection location S ₁ of the downstream circuit 102 in the engine cooling circuit 10, that is, downstream from the engine 1 and upstream from the engine radiator 12. Thirty first valves V ₁ are opened. Therefore, warm engine refrigerant after having absorbed heat by the engine 1 and before radiating heat by the engine radiator can be caused to flow into the motor cooling circuit 20. Therefore, the viscosity reduction of the motor refrigerant in the motor cooling circuit 20 can be promoted, and the pumping load of the electric pump P ₂ can be reduced.

(7) In the first control of the output suppression control, the fifth connection point S ₅ of the downstream circuit 202 in the motor cooling circuit 20, that is, the second outflow communication path 32 connected to the upstream side of the motor radiator 22. Three valve V ₃ is opened. Therefore, the motor refrigerant before radiating heat from the motor radiator 22 can flow into the engine cooling circuit 10. Therefore, excessive cooling of the refrigerant can be suppressed, which contributes to a reduction in energy efficiency.

(8) In the fail control, the engine 1 is forcibly started and the engine cooling circuit 10 and the motor cooling circuit 20 are communicated with each other. Therefore, only the engine refrigerant in the engine cooling circuit 10 is used by the mechanical pump P ₁ . In addition, the motor refrigerant of the motor cooling circuit 20 can be pumped. Therefore, even in emergency situations, when the electric pump P ₂ has failed, it is possible to distribute the motor coolant of the motor cooling circuit 20. Therefore, local overheating of the motor refrigerant can be avoided and thermal protection of the cooling target can be ensured.
The refrigerant in the fail control flows from the engine cooling circuit 10 into the motor cooling circuit 20 and is cooled by the motor radiator 22 and then cooled by the engine radiator 12. Thus, since the refrigerant can be cooled by the two radiators 12 and 22, thermal protection can be ensured, which contributes to improving the cooling efficiency.

(9) in the output suppression control, if the output of the electric pump P ₂ is Rarere suppressed as the output of the mechanical pump P ₁ is high, many quantity of the motor coolant pumped by the more mechanical pump P ₁ output is high At the same time, the amount of motor refrigerant pumped by the electric pump P ₂ is reduced. Accordingly, the mechanical pump P ₁ and the electric pump P ₂ can appropriately share the pressure-feeding load, and the reduction in energy efficiency can be appropriately suppressed.

[5. Modified example]
Finally, a modification of the cooling system of this embodiment will be described.
For example, an on-off valve whose opening degree can be adjusted may be used for the above-described valves V _{1 to} V ₄ . In this case, the output suppression control and fail control, in order to enhance the thermal protection of the cooling system of the electric motor 2, as the engine coolant temperature T _E is higher, the valve V ₁ ~V ₄ being opened opening Is preferably reduced.

Further, instead of the valves V _{1 to} V ₃ interposed in the communication passages 30, 31, 32, three-way opening / closing valves may be used at the connection points S _{1 to} S ₆ . This three-way opening / closing valve opens one of the two inflow ports and shuts off the other to connect one inflow port with one outflow port, or opens one of the two outflow ports. In addition, the other inlet is connected to one outlet by blocking the other. When such a three-way opening / closing valve is used, the refrigerant flowing through the other of the two inlets or outlets can be shut off, so the amount of refrigerant flowing to the open side of the three-way opening / closing valve Can be increased. Therefore, temperature controllability can be improved.

In addition, the following condition B3 or B4 may be added to the basic condition of the refrigerant temperature condition.
Condition B3: The motor refrigerant temperature T _M is lower than the allowable upper limit temperature T ₀ (T _M <T ₀ ). Condition B4: The engine refrigerant temperature T _E is higher than the first predetermined temperature T ₁ (T _E > T ₁ ). When a certain condition B3 is added to the basic condition, the high-temperature motor refrigerant is cooled only by the motor cooling circuit 20, and the thermal protection of the cooling system of the electric motor 2 can be ensured. In addition, by adding the condition B4 to the basic condition, it is possible to prevent the high-viscosity engine refrigerant from flowing into the motor cooling circuit 20, and to suppress an increase in the pumping load of the electric motor 2.

Note that the configuration is not limited to a configuration in which various control targets are centrally controlled by the single control device 50, and a configuration in which the control targets are distributedly controlled by a plurality of control devices (control units). For example, the engine ECU (control unit) may control the engine 1 and the motor ECU (control unit) may control the valves V _{1 to} V ₄ . Regardless of the configuration of the control device that is the subject of control, the same effects as those of the above-described embodiment can be obtained.

1 Engine 10 Engine cooling circuit (first circuit)
12 Engine radiator (first radiator)
DESCRIPTION OF SYMBOLS 2 Electric motor 3 Inverter 4 Car charger 6 Travel drive battery 9 Auxiliary battery 20 Motor cooling circuit (second circuit)
22 Motor radiator (second radiator)
30 Inflow communication passage (first series passage)
31 First outflow communication path 32 Second outflow communication path (second communication path)
41 Engine refrigerant temperature sensor (first sensor)
42 Motor refrigerant temperature sensor (second sensor)
50 Control device (control unit)
510 determination unit 520 command unit 530 valve command unit 540 pump command unit 541 output calculation unit 550 engine command unit T ₀ allowable upper limit temperature T ₁ first predetermined temperature T ₂ second predetermined temperature T _E engine refrigerant temperature T _M motor refrigerant temperature P ₁ mechanical pump (first pump)
P ₂ electric pump (second pump)
V ₁ first valve V ₂ second valve V ₃ third valve (second valve)
V ₄ The fourth valve alpha, beta, gamma correction factor

Claims (9)

A first circuit for circulating a first refrigerant pumped by an engine-driven first pump and cooling the engine;
A second circuit in which a second refrigerant pumped by an electric second pump flows and cools the electric motor;
A valve interposed in a communication path communicating the first circuit and the second circuit;
A cooling system comprising: a control unit that opens the valve when a predetermined condition including that the engine is driving the first pump is satisfied, and suppresses an output of the second pump. The cooling system according to claim 1, wherein the predetermined condition includes that the temperature of the first refrigerant is lower than an upper limit temperature allowed in the second circuit. The cooling system according to claim 1 or 2, wherein when the predetermined condition is satisfied, the control unit increases the output suppression amount of the second pump as the temperature of the second refrigerant is lower. The said control part makes the output suppression amount of said 2nd pump large, so that the temperature of said 1st refrigerant | coolant is low, when the said predetermined condition is satisfied. Cooling system. The cooling system according to any one of claims 1 to 4, wherein the predetermined condition includes that the temperature of the first refrigerant is higher than the temperature of the second refrigerant. The first circuit is provided with a first radiator that radiates heat of the first refrigerant,
The communication path has a first series path that communicates the second circuit with the upstream side of the first radiator and the upstream side of the engine in the first circuit,
The cooling system according to claim 1, wherein the valve has a first valve interposed in the first series passage. The second circuit is provided with a second radiator that dissipates the second refrigerant,
The communication path has a second communication path that connects the first circuit with the upstream side of the second radiator in the second circuit,
The cooling system according to claim 1, wherein the valve includes a second valve interposed in the second communication path. 8. The control unit according to claim 1, wherein the control unit starts the engine and opens the valve when the second pump breaks down while the engine is stopped. 9. Cooling system. The said control part enlarges the output suppression amount of said 2nd pump, so that the output of said 1st pump is high at the time of the said predetermined conditions being satisfied, The any one of Claims 1-8 characterized by the above-mentioned. Cooling system.

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