JP2008184994A - Electric water pump control device - Google Patents

Abstract

An electric water pump control device capable of preventing a decrease in engine speed immediately after engine startup is provided.
An electric water pump control device includes an internal-combustion-engine speed determination unit and an electric water pump drive unit. The internal combustion engine rotational speed determination means determines whether or not the rotational speed of the internal combustion engine is greater than a predetermined value after the internal combustion engine is started. The electric water pump drive means stops the drive of the electric water pump from when the internal combustion engine is started until the internal combustion engine speed determination means determines that the rotational speed of the internal combustion engine is greater than a predetermined value. As a result, the motor that performs cranking of the internal combustion engine can receive electric power necessary for cranking from the battery, and can prevent a decrease in the rotational speed of the internal combustion engine.
[Selection] Figure 2

Description

  The present invention relates to a control device for an electric water pump that controls an electric water pump that circulates engine coolant.

  Conventionally, a technique using an electric water pump (hereinafter referred to as “electric W / P”) that circulates cooling water for cooling an engine has been proposed. For example, Patent Document 1 describes an exhaust heat recovery device that circulates cooling water even after the engine is stopped. Patent Document 2 describes a technique for stopping an electric water pump after the mechanical water pump is actuated after the engine is started. Patent Document 3 describes a technique for providing a limit value for an electric load that can be used when the engine is started according to the remaining capacity of the battery power. Patent Document 4 describes a technique for stopping the operation of the electric water pump for a predetermined period after the engine is cold-started.

JP-A-2-104952 JP 2006-161745 A JP 2002-327668 A JP 2006-214279 A

  By the way, when starting the engine, it is necessary to perform cranking in which the engine is rotated by a motor. However, at this time, when the electric W / P is driven, electric power is consumed by the electric W / P, so that the power consumption of the motor used for cranking is reduced and the engine speed is reduced. . Such a decrease in engine speed may cause engine misfire.

  In the techniques described in Patent Documents 1 to 4 described above, when the electric W / P is driven at the time of starting the engine, electric power is consumed by the electric W / P, and the engine speed decreases. End up.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to prevent the engine speed from decreasing immediately after the engine is started.

  In one aspect of the present invention, a control device for an electric water pump that controls an electric water pump that circulates cooling water in an internal combustion engine has a rotational speed of the internal combustion engine that is greater than a predetermined value after the internal combustion engine is started. Internal combustion engine speed determining means for determining whether or not the engine speed is larger, and from when the internal combustion engine is started until the internal combustion engine speed determining means determines that the engine speed is greater than a predetermined value. Electric water pump driving means for stopping the driving of the electric water pump.

  The control device for the electric water pump is preferably used for controlling the electric water pump that circulates the cooling water in the internal combustion engine. The control device for the electric water pump includes an internal combustion engine speed determination means and an electric water pump drive means. The internal combustion engine rotational speed determination means is, for example, an ECU (Electronic Control Unit), and determines whether the rotational speed of the internal combustion engine is greater than a predetermined value after the internal combustion engine is started. The electric water pump driving means drives the electric water pump from when the internal combustion engine is started until the internal combustion engine rotational speed determination means determines that the rotational speed of the internal combustion engine is greater than a predetermined value. To stop. Thereby, the motor that performs cranking of the internal combustion engine can receive power necessary for cranking from the battery, and can prevent a decrease in the rotational speed of the internal combustion engine.

  In a preferred embodiment of the control apparatus for the electric water pump, the predetermined value is a value of the rotational speed of the internal combustion engine when the rotational speed of the internal combustion engine increases due to combustion in a combustion chamber of the internal combustion engine. .

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[Vehicle configuration]
First, a hybrid vehicle to which a hybrid vehicle cooling system according to this embodiment is applied will be described with reference to FIG.

  FIG. 1 is a diagram showing a schematic configuration of the hybrid vehicle 100. Hybrid vehicle 100 mainly includes an engine (internal combustion engine) 1, an axle 2, wheels 3, motors (motor generators) MG1 and MG2, planetary gear 4, inverter 5, battery 6, and SOC sensor 6a. , ECU (Electronic Control Unit) 20.

  The axle 2 is a part of a power transmission system that transmits the power of the engine 1 and the motor MG2 to the wheels 3. The wheels 3 are wheels of the hybrid vehicle 100, and only the left and right front wheels are particularly shown in FIG. The engine 1 is constituted by a gasoline engine or the like, and functions as a power source that outputs the main driving force of the hybrid vehicle 100. The engine 1 is controlled variously by the ECU 20. Specifically, the ECU 20 controls the engine speed, and controls the opening (throttle opening) of a throttle valve (not shown).

  The motor MG1 is configured to function mainly as a generator for charging the battery 6 or a generator for supplying electric power to the motor MG2. The motor MG2 is mainly configured to function as an electric motor that assists (assists) the output of the engine 1. These motors MG1 and MG2 are configured as, for example, synchronous motor generators, and include a rotor having a plurality of permanent magnets on the outer peripheral surface, and a stator wound with a three-phase coil that forms a rotating magnetic field. The planetary gear (planetary gear mechanism) 4 is configured to be able to distribute the output of the engine 1 to the motor MG1 and the axle 2 and functions as a power split mechanism.

  The inverter 5 is a DC / AC converter that controls power input / output between the battery 6 and the motors MG1 and MG2. For example, the inverter 5 converts the DC power taken out from the battery 6 into AC power, or supplies AC power generated by the motor MG1 to the motor MG2 and converts the AC power generated by the motor MG1 into DC power. It can be converted to and supplied to the battery 6.

  The battery 6 is a rechargeable storage battery configured to be able to function as a power source for driving the motors MG1 and MG2 and an electric water pump described later. The SOC sensor 6a is a sensor configured to be able to detect the state of charge of the battery 6 (hereinafter also referred to as “SOC (State Of Charge)”). The SOC sensor 6a is electrically connected to the ECU 20, and the SOC of the battery 6 is always grasped by the ECU 20.

[Configuration of cooling system]
FIG. 2 is a diagram showing a schematic configuration of a cooling system 50 to which the control device for the electric water pump according to the embodiment of the present invention is applied. In FIG. 1, solid arrows indicate the flow of cooling water, and broken arrows indicate input / output of signals. A solid line indicated by a bold line indicates a passage (cooling water passage) through which the cooling water flows.

  The cooling system 50 mainly includes an engine 1, a radiator 13, a thermostat 14, an electric water pump (hereinafter referred to as “electric W / P”) 15, a crank angle sensor 16, and a cooling water passage 17a. , 17b, 17c and an ECU (Engine Control Unit) 20.

  The cooling system 50 according to the present embodiment is a system for mainly cooling the engine 1 using cooling water and warming up the engine 1 and the like using cooling water. In this case, the cooling water circulates through the cooling water passages 17a, 17b, and 17c. Hereinafter, when the cooling water passages 17a to 17c are not distinguished from each other, they are simply used as the “cooling water passage 17”.

  The engine 1 is a device that generates power by burning a mixture of supplied fuel and air. The engine 1 is constituted by a gasoline engine, a diesel engine, or the like. The crank angle sensor 16 is attached to the engine 1. The crank angle sensor 16 detects the rotational speed of the engine 1 and supplies the detected rotational speed of the engine 1 to the ECU 20 as a detection signal S1.

  In the radiator 13, the cooling water passing through the inside thereof is cooled by outside air. In this case, cooling of the cooling water in the radiator 13 is promoted by the wind introduced by the rotation of the electric fan (not shown). The electric W / P 15 circulates the cooling water in the cooling water passage 17 by driving an electric motor. Specifically, the electric W / P 15 is supplied with electric power from the battery 16 and the rotational speed and the like are controlled by a control signal S2 supplied from the ECU 20.

  The thermostat 14 is configured by a valve that opens and closes according to the temperature of the cooling water. Basically, the thermostat 14 opens when the temperature of the cooling water becomes high. In this case, the cooling water passage 17 b and the cooling water passage 17 c are connected via the thermostat 14, and the cooling water passes through the radiator 13. Thereby, a cooling water is cooled and the overheating of the engine 1 is suppressed. On the other hand, when the temperature of the cooling water is relatively low, the thermostat 14 is closed. In this case, the cooling water does not pass through the radiator 13. Thereby, since the temperature fall of a cooling water is suppressed, the overcool of the engine 1 is suppressed.

  The ECU 20 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown). The ECU 20 controls the entire operation of the hybrid vehicle 100 and controls the electric W / P 15 based on the detection signal S1 supplied from the crank angle sensor 16 described above. Specifically, the ECU 20 performs control for stopping the driving of the electric W / P 15 (hereinafter simply referred to as “stop control”) in order to sufficiently increase the rotational speed of the engine 1 when the engine 1 is started. Do. Further, the ECU 20 determines whether or not the rotational speed of the engine 1 is larger than a predetermined value based on the detection signal S1 supplied from the crank angle sensor 16. This predetermined value is a preset value and is stored in the ROM of the ECU 20 or the like.

  This predetermined value is the value of the rotational speed when the rotational speed of the engine 1 is sufficiently increased, that is, the rotational speed when the rotational speed is increased by combustion in the combustion chamber of the engine 1 exceeding the rotational speed due to cranking. It is a number value. Specifically, a value of the rotational speed when the rotational speed increases due to combustion in the combustion chamber of the engine 1 is measured in advance, and the measured rotational speed value is set as the predetermined value. For example, in the case of a hybrid vehicle, the predetermined value is about 1200 [rpm].

  When the ECU 20 determines that the rotational speed of the engine 1 is greater than a predetermined value, that is, when it is determined that the rotational speed of the engine 1 has increased sufficiently, the ECU 20 starts driving the electric W / P 15. (Hereinafter simply referred to as “start control”). As described above, the ECU 20 corresponds to the control device for the electric water pump in the present invention. Specifically, the ECU 20 functions as an internal combustion engine speed determination unit and an electric water pump drive unit.

[Control method of electric W / P]
Next, a method for controlling the electric W / P 15 performed by the ECU 20 will be described. As described above, the ECU 20 performs control (stop control) to stop the electric W / P 15 in order to sufficiently increase the rotational speed of the engine 1 when the engine 1 is started.

  The reason why such stop control is performed is as follows. When the engine 1 is started, the engine 1 is cranked by the motor MG2. At this time, since the temperature in the crank chamber of the engine 1 is about −30 [° C.], the lubricating oil is in a highly viscous state. When the motor MG2 performs cranking in such a state, the power consumed by the motor MG2 increases.

  Therefore, at this time, if the electric power of the battery 6 is consumed by driving the electric W / P 15, the motor MG 2 may not be able to receive the electric power necessary for driving from the battery 6. . When the motor MG2 cannot receive the power necessary for driving from the battery 6, the rotational speed of the engine 1 decreases.

  For this reason, the ECU 20 performs control to stop the electric W / P 15 when the engine 1 is started.

  In the above-described embodiment, an example in which the present invention is applied to a hybrid vehicle has been described, but it goes without saying that examples to which the present invention can be applied are not limited to hybrid vehicles.

[Control processing of electric W / P]
Next, the control process of the electric W / P 5 according to the present embodiment will be described with reference to FIG.

  FIG. 3 is a flowchart showing the control process of the electric W / P 15. In step S101, the ECU 20 determines whether or not the engine 1 has started. Specifically, the ECU 20 determines that the engine 1 has started starting when the ECU 20 itself has transmitted a control signal for starting to the engine 1. If the ECU 20 determines in step S101 that the engine 1 has not started (step S101: No), the ECU 20 ends the process, and if it determines that the engine 1 has started (step S101). : Yes), the process proceeds to step S102.

  In step S102, the ECU 20 determines whether or not a flag indicating ON / OFF of the start control of the electric W / P 15 (hereinafter referred to as an “electric W / P operation permission flag”) is set to ON. This is because when the engine 1 is started, if the electric W / P operation permission flag is set to ON, the electric W / P 15 is driven, and thus the ECU 20 performs stop control of the electric W / P. It is necessary.

  In step S102, when the ECU 20 determines that the electric W / 15 operation permission flag is set to ON (step S102: Yes), the process proceeds to step S103. On the other hand, if the ECU 20 determines that the electric W / P15 operation permission flag is set to OFF (step S102: No), the ECU 20 proceeds to step S104.

  In step S103, the ECU 20 sets the electric W / P15 operation permission flag to OFF. By doing in this way, stop control which stops electric W / P15 is performed, and the electric power of battery 6 is not consumed by electric W / P15. Thereby, since motor MG2 can receive the electric power required for cranking from battery 6, it can prevent the rotation speed of engine 1 from decreasing.

  In step S104, the ECU 20 determines whether or not the rotational speed of the engine 1 is greater than a predetermined value. If the ECU 20 determines in step S104 that the rotational speed of the engine 1 is not greater than a predetermined value (step S104: No), the operation of step S104 is repeated, and the rotational speed of the engine 1 is greater than the predetermined value. If it is determined that the value is also larger (step S104: Yes), the process proceeds to step S105.

  As described above, this predetermined value exceeds the value of the rotational speed when the rotational speed of the engine 1 is sufficiently increased, that is, exceeds the rotational speed due to cranking, and the rotational speed due to combustion in the combustion chamber of the engine 1 This is the value of the rotation speed when increases. If the rotation of the engine 1 does not exceed the predetermined value and the drive of the electric W / P 15 starts, the motor MG2 cannot receive the power necessary for cranking from the battery 6. As a result, the rotational speed of the engine 1 decreases. For this reason, in step S104, the ECU 20 stops the driving of the electric W / P 15 until the rotational speed of the engine 1 becomes larger than a predetermined value.

  In step S105, the ECU 20 ends the process after turning on the electric W / P15 operation permission flag. At this stage, the engine 1 is in a state in which the rotational speed increases due to combustion in the combustion chamber of the engine 1, and therefore the rotational speed of the engine 1 decreases even when the drive of the electric W / P 15 is started. Never do.

  As described above, the control device for the electric W / P includes the internal combustion engine speed determination means for determining whether or not the engine speed is greater than a predetermined value after starting the engine, and starting the engine. Electric water pump drive means for stopping the drive of the electric W / P from the time until the internal combustion engine speed judgment means judges that the engine speed is greater than a predetermined value. As a result, the motor that performs cranking of the engine can receive power necessary for cranking from the battery, and can prevent a decrease in the rotational speed of the engine.

It is a figure showing the schematic structure of the hybrid vehicle concerning this embodiment. It is a figure which shows schematic structure of the cooling system which concerns on this embodiment. It is a flowchart which shows the control process of electric W / P.

Explanation of symbols

1 engine (internal combustion engine)
13 Radiator 14 Thermostat 15 Electric water pump (Electric W / P)
16 Crank angle sensor 17 Cooling water passage 20 ECU
50 Cooling system 100 Hybrid vehicle

Claims (2)

In a control device for an electric water pump that controls an electric water pump that circulates cooling water in an internal combustion engine,
Internal combustion engine speed determination means for determining whether or not the speed of the internal combustion engine is greater than a predetermined value after the internal combustion engine is started;
Electric water pump drive means for stopping the drive of the electric water pump from when the internal combustion engine is started until the internal combustion engine speed determination means determines that the rotational speed of the internal combustion engine is greater than a predetermined value And a control device for an electric water pump.   2. The electric water pump according to claim 1, wherein the predetermined value is a value of a rotation speed of the internal combustion engine when the rotation speed of the internal combustion engine increases due to combustion in a combustion chamber of the internal combustion engine. Control device.

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