Start control device for internal combustion engine

Abstract

To provide suppress a power consumption while shortening a time until a completion of a start of an internal combustion engine.SOLUTION: A start control device 100 for an internal combustion engine for starting the internal combustion engine 1 by controlling a starter motor 3 for cranking the internal combustion engine 1, and a motor 2 connected to the internal combustion engine 1 in a power transmissible manner. The device includes: a target cranking rotation speed acquiring means 102 for acquiring a target cranking rotation speed based on a temperature of the internal combustion engine 1; an estimated cranking rotation speed acquiring means 102 for acquiring an estimated cranking rotation speed which is a cranking rotation speed by the starter motor 3 that is estimated based on the temperature of the internal combustion engine 1 and an applied voltage to the starter motor 3; a control means 105 for controlling a start assist by the motor 2 in addition to a cranking by the starter motor 3 when the estimated cranking rotation speed is less than the target cranking rotation speed at the start of the internal combustion engine 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a start control device for an internal combustion engine. [Background technology]

[0002] Patent Document 1 discloses a technology relating to the start-up control of an internal combustion engine mounted on a vehicle, in which after a starter motor is started, it is determined whether the engine speed is equal to or greater than a reference speed, and if the engine speed is not equal to or greater than the reference speed, a generator motor is started as an electric motor to assist the start of the engine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-217225 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology disclosed in Patent Document 1, after attempting cranking using the starter motor, if it is determined that the engine is not rotating fast enough, the generator motor assists the engine start. This delays the timing at which the assist begins, and it takes a long time to complete the engine start. Furthermore, cranking continues using only the starter motor until it is determined that the engine is not rotating fast enough, which unnecessarily consumes power.

[0005] The present invention has been made in view of the above circumstances, and has an object to shorten the time until the start of an internal combustion engine is completed and to suppress power consumption. [Means for solving the problem]

[0006] The internal combustion engine start control device of the present invention is a start control device for an internal combustion engine that controls a starter motor that cranks the internal combustion engine and an electric motor that is connected to the internal combustion engine so as to be able to transmit power, and starts the internal combustion engine, and is characterized in that it comprises: a temperature acquisition means that acquires the temperature of the internal combustion engine; a voltage acquisition means that acquires the voltage applied to the starter motor; a target cranking rotation speed acquisition means that acquires a target cranking rotation speed based on the temperature of the internal combustion engine acquired by the temperature acquisition means; an estimated cranking rotation speed acquisition means that acquires an estimated cranking rotation speed, which is the cranking rotation speed by the starter motor, estimated based on the temperature of the internal combustion engine acquired by the temperature acquisition means and the applied voltage acquired by the voltage acquisition means; and a control means that, when the estimated cranking rotation speed is less than the target cranking rotation speed at the start of the internal combustion engine, controls to perform start assistance by the electric motor in addition to cranking by the starter motor. [Effects of the Invention]

[0007] According to the present invention, it is possible to shorten the time until the start of an internal combustion engine is completed and to suppress power consumption. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a schematic configuration of a main part of an automobile according to an embodiment; [Figure 2] 4 is a flowchart showing a process executed by an ECU. [Figure 3] FIG. 4 is a diagram for explaining a target cranking rotation speed and an estimated cranking rotation speed. DETAILED DESCRIPTION OF THE INVENTION

[0009] A start control device for an internal combustion engine according to one embodiment of the present invention is an internal combustion engine start control device (100) that controls a starter motor (3) that cranks an internal combustion engine (1) and an electric motor (2) that is connected to the internal combustion engine (1) so as to be capable of transmitting power, thereby starting the internal combustion engine (1), and includes temperature acquisition means (103) that acquires a temperature of the internal combustion engine (1), voltage acquisition means (104) that acquires a voltage applied to the starter motor (3), and target cranking rotation speed acquisition means that acquires a target cranking rotation speed based on the temperature of the internal combustion engine (1) acquired by the temperature acquisition means (103). (102), an estimated cranking rotation speed acquisition means (102) for acquiring an estimated cranking rotation speed, which is the cranking rotation speed by the starter motor (3), estimated based on the temperature of the internal combustion engine (1) acquired by the temperature acquisition means (103) and the applied voltage acquired by the voltage acquisition means (104), and a control means (105) for controlling the electric motor (2) to perform start-up assistance in addition to cranking by the starter motor (3) when the estimated cranking rotation speed is less than the target cranking rotation speed at the time of starting the internal combustion engine (1). This reduces the time required to complete the start of the internal combustion engine (1) and reduces power consumption. [Example]

[0010] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. FIG. 1 shows a schematic configuration of the main parts of an automobile according to the embodiment. As shown in FIG. 1, the automobile is a hybrid vehicle equipped with an engine 1 and a motor generator 2.

[0011] The engine 1 is an internal combustion engine having multiple cylinders, and is configured to perform a series of four strokes for each cylinder, consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke, and to output power by burning gasoline fuel. The power output from the output shaft of the engine 1 is transmitted to drive wheels 9 via a transmission 6, an output shaft 7, and a rotating shaft 8. The engine 1 is provided with a starter motor 3 that cranks the engine 1 to start it. The starter motor 3 is driven by a battery 11 as a power source. The engine 1 is also provided with a temperature sensor 12 that measures the temperature of the cooling water. The temperature sensor 12 may also measure the temperature of the engine 1 oil.

[0012] The motor generator 2 is coupled to the engine 1 via pulleys 4a, 4b and a belt 5 so as to be able to transmit power. The motor generator 2 is connected to a battery 11 via a power converter 10. The motor generator 2 functions as an electric motor that rotates the output shaft of the engine 1 by being driven using the battery 11 as a power source. The motor generator 2 also functions as a generator that generates power to charge the battery 11 by being driven by the output shaft of the engine 1. Note that, although the example in which the motor generator 2 is coupled to the engine 1 via pulleys 4a, 4b and a belt 5 has been given, the present invention is not limited to this, and the motor generator 2 may be coupled to the engine 1 so as to be able to transmit power via a clutch, gear, etc.

[0013] The automobile is also equipped with an ECU (Electronic Control Unit) 100 that electronically controls various functions of the automobile. Various sensors including a temperature sensor 12 are connected to the ECU 100. The ECU 100 is responsible for engine control, and performs fuel supply control, opening and closing control of intake and exhaust valves, and ignition timing control. The ECU 100 is configured by a computer unit that includes, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), a flash memory for storing backup data, etc., an input port, and an output port.

[0014] In this embodiment, the ECU 100 functions as a start control device for an internal combustion engine to which the present invention is applied. The following description will focus on the function of the start control device for an internal combustion engine to which the present invention is applied. As shown in FIG. 1, the ECU 100 includes a storage unit 101, a reading unit 102, a temperature acquisition unit 103, a voltage acquisition unit 104, and a control unit 105.

[0015] As shown in FIG. 3(a), the memory unit 101 stores, in table form, target cranking speeds that are preset for each temperature range (°C) of the cooling water temperature. The target cranking speed is the cranking speed at which the engine can be started using only the starter motor 3. For example, a cooling water temperature of "0" represents a temperature range of 0 to -10, and "-10" represents a temperature range of -10 to -20. In low-temperature environments, the target cranking speed tends to decrease due to increased engine friction, etc. The target cranking speed is a value that is determined in advance through tests on an actual machine and calculations.

[0016] As shown in FIG. 3B, the storage unit 101 also stores, in table form, estimated cranking rotation speeds that are preset for each temperature range (°C) of the coolant temperature and each voltage range (V) of the voltage applied to the starter motor 3. The estimated cranking rotation speed is the cranking rotation speed of the starter motor 3 estimated based on the coolant temperature and the voltage applied to the starter motor 3. For example, a coolant temperature of "0" represents a temperature range of 0 to -10, and "-10" represents a temperature range of -10 to -20. For example, an applied voltage of "9" represents a voltage range of 9 to 10, and "10" represents a voltage range of 10 to 11. In low-temperature environments, the estimated cranking rotation speed tends to decrease due to increased engine friction, etc. In low-temperature environments, the performance of the battery 11 decreases, the applied voltage becomes low, and the estimated cranking rotation speed tends to decrease. The estimated cranking rotation speed is a value previously determined through tests and calculations using an actual vehicle. Although not shown in Figure 3(b), the estimated cranking speeds in each field of the table are associated with estimated times required to reach those speeds. The estimated times are values ​​previously obtained through tests on an actual machine and calculations.

[0017] The reading unit 102 reads the target cranking rotation speed, the estimated cranking rotation speed and the corresponding estimated time from the memory unit 101 based on the cooling water temperature acquired by the temperature acquisition unit 103 and the applied voltage to the starter motor 3 acquired by the voltage acquisition unit 104.

[0018] The temperature acquisition unit 103 acquires the coolant temperature measured by the temperature sensor 12. Note that, although the coolant temperature or oil temperature is acquired as the temperature of the engine 1, it is not limited to this. As long as it represents the temperature of the engine 1, it is also possible to measure the temperature of the housing of the engine 1, for example.

[0019] The voltage acquisition unit 104 acquires the voltage applied to the starter motor 3 .

[0020] When starting the engine 1, the control unit 105 compares the estimated cranking rotation speed read by the reading unit 102 from the memory unit 101 with the target cranking rotation speed. If the estimated cranking rotation speed is less than the target cranking rotation speed, the control unit 105 controls the starter motor 3 to crank and the motor generator 2 to function as an electric motor to provide start-up assistance. If the estimated cranking rotation speed is equal to or greater than the target cranking rotation speed, the control unit 105 determines whether the estimated time read by the reading unit 102 from the memory unit 101 is equal to or greater than a predetermined time. If the estimated time is less than the predetermined time, the control unit 105 controls the starter motor 3 to crank only, whereas if the estimated time is equal to or greater than the predetermined time, the control unit 105 controls the starter motor 3 to crank and the motor generator 2 to function as an electric motor to provide start-up assistance.

[0021] 2 is a flowchart showing the process executed by the ECU 100, which functions as a start control device for an internal combustion engine. This flowchart is executed when the engine 1 is started. In step S1, the temperature acquisition unit 103 acquires the coolant temperature measured by the temperature sensor 12. Furthermore, the voltage acquisition unit 104 acquires the voltage applied to the starter motor 3.

[0022] In step S2, the reading unit 102 reads the target cranking speed, the estimated cranking speed and the corresponding estimated time from the memory unit 101 based on the coolant temperature acquired in step S1 and the applied voltage to the starter motor 3 acquired in step S1.

[0023] In step S3, the control unit 105 determines whether the estimated cranking rotation speed acquired in step S2 is equal to or greater than the target cranking rotation speed acquired in step S2. If the estimated cranking rotation speed is equal to or greater than the target cranking rotation speed, the process proceeds to step S4. If the estimated cranking rotation speed is less than the target cranking rotation speed, the process proceeds to step S6.

[0024] In step S4, the control unit 105 determines whether the estimated time acquired in step S2 is equal to or greater than a predetermined time. If the estimated time is equal to or greater than the predetermined time, the process proceeds to step S6. If the estimated time is less than the predetermined time, the process proceeds to step S5.

[0025] In step S5, the control unit 105 controls the engine 1 to start by cranking using only the starter motor 3.

[0026] In step S6, the control unit 105 controls the engine 1 to start by cranking the engine with the starter motor 3 and by causing the motor generator 2 to function as an electric motor to perform start-up assistance. In steps S5 and S6, the ECU 100 may optimize the fuel injection amount and the air amount by increasing or decreasing them according to the cranking rotation, thereby reducing exhaust gas when the engine 1 is started.

[0027] As described above, whether or not the engine 1 can be started by the starter motor 3 alone is determined before cranking, and if necessary, starting assistance is performed by the motor generator 2 in addition to cranking by the starter motor 3. This shortens the time required to complete starting the engine 1 and reduces power consumption. Furthermore, even if the engine 1 can be started using only the starter motor 3 but requires time, the motor generator 2 assists in starting in addition to cranking by the starter motor 3. This allows the time required to complete the start of the engine 1 to be shortened.

[0028] In this embodiment, even if the estimated cranking rotation speed is equal to or higher than the target cranking rotation speed, if the estimated time is equal to or higher than a predetermined time, starting assistance is performed by the motor generator 2 in addition to cranking by the starter motor 3, but this is not limited to this. If the estimated cranking rotation speed is equal to or higher than the target cranking rotation speed, cranking may be performed only by the starter motor 3 without taking the estimated time into consideration.

[0029] In this embodiment, the memory unit 101 stores a target cranking speed corresponding to the temperature of the engine 1, and the target cranking speed is acquired by reading the stored target cranking speed using the reading unit 102. In other words, the reading unit 102 functions as the target cranking speed acquisition means of the present invention. However, this is not limited to this. For example, the target cranking speed acquisition means may be configured to include a calculation unit that calculates the target cranking speed using a predetermined calculation formula based on the coolant temperature acquired by the temperature acquisition unit 103. In this embodiment, the memory unit 101 stores an estimated cranking rotation speed corresponding to the temperature of the engine 1 and the voltage applied to the starter motor 3, and the estimated cranking rotation speed is acquired by reading the stored estimated cranking rotation speed using the reading unit 102. In other words, the reading unit 102 functions as the estimated cranking rotation speed acquisition means referred to in the present invention. However, this is not limited to this. For example, the estimated cranking rotation speed acquisition means may be configured to include a calculation unit that calculates the estimated cranking rotation speed using a predetermined calculation formula based on the coolant temperature acquired by the temperature acquisition unit 103 and the voltage applied to the starter motor 3 acquired by the voltage acquisition unit 104. The same applies to the estimated time.

[0030] Although the embodiments of the present invention have been described in detail above with reference to the drawings, each embodiment merely shows a specific example of how the present invention can be implemented. The technical scope of the present invention is not limited to each embodiment. Various modifications of the present invention are possible within the scope of the gist of the present invention, and these modifications are also included within the technical scope of the present invention. The internal combustion engine start control device to which the present invention is applied is configured by a computer device equipped with, for example, a CPU, ROM, RAM, etc., and the functions of each means are realized by the CPU executing a predetermined program stored, for example, in the ROM. [Explanation of symbols]

[0031] 1: engine, 2: motor generator, 3: starter motor, 100: ECU, 101: storage unit, 102: reading unit, 103: temperature acquisition unit, 104: voltage acquisition unit, 105: control unit

Claims

1. A start control device for an internal combustion engine that controls a starter motor that cranks the internal combustion engine and an electric motor that is connected to the internal combustion engine so as to be able to transmit power, and starts the internal combustion engine, a temperature acquisition means for acquiring a temperature of the internal combustion engine; a voltage acquisition means for acquiring a voltage applied to the starter motor; a target cranking rotation speed acquisition means for acquiring a target cranking rotation speed based on the temperature of the internal combustion engine acquired by the temperature acquisition means; an estimated cranking rotation speed acquisition means for acquiring an estimated cranking rotation speed, which is the cranking rotation speed of the starter motor, estimated based on the temperature of the internal combustion engine acquired by the temperature acquisition means and the applied voltage acquired by the voltage acquisition means; and control means for controlling the internal combustion engine so that, when the estimated cranking rotation speed is lower than the target cranking rotation speed at the time of starting the internal combustion engine, in addition to cranking by the starter motor, start-up assistance by the electric motor is performed.

2. 2. The internal combustion engine start control device according to claim 1, wherein the control means controls the internal combustion engine so that cranking is performed only by the starter motor when the estimated cranking rotation speed is equal to or higher than the target cranking rotation speed at the time of starting the internal combustion engine.

3. an estimated time acquisition means for acquiring an estimated time until the estimated cranking rotation speed is reached; 3. The internal combustion engine start control device according to claim 2, wherein the control means controls the starter motor to perform start-up assistance in addition to cranking when the estimated time is equal to or longer than a predetermined time, even when the estimated cranking speed is equal to or higher than the target cranking speed.

4. the target cranking rotation speed corresponding to the temperature of the internal combustion engine is stored in a storage unit, 4. The internal combustion engine start control device according to claim 1, wherein the target cranking rotation speed acquisition means reads the target cranking rotation speed from the memory unit based on the temperature of the internal combustion engine acquired by the temperature acquisition means.

5. the estimated cranking rotation speed according to the temperature of the internal combustion engine and the applied voltage is stored in a storage unit, 4. A start control device for an internal combustion engine according to claim 1, wherein the estimated cranking rotation speed acquisition means reads the estimated cranking rotation speed from the memory unit based on the temperature of the internal combustion engine acquired by the temperature acquisition means and the applied voltage acquired by the voltage acquisition means.

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