Drive unit

Abstract

To suppress inconvenience that is caused by unexpected excessive torque, which may be generated when charging an electric storage device with generated electric power obtained by driving a motor as a power generator in a state where an engine outputs power to a driving shaft, acting on the driving shaft.SOLUTION: A driving device comprises: an engine that outputs power to a driving shaft; a motor, connected to a crank shaft of the engine, which can generate electric power; an electric storage device that exchanges electric power with the motor; and a control device that controls the engine and the motor. The control device controls the engine and the motor so that required torque that is required in the driving shaft is outputted to the driving shaft, and target generated electric power, which is obtained by guarding generated electric power required based on an electric storage ratio of the electric storage device to an upper limit at an upper limit of power generation amounts based on a rotation speed of the driving shaft, is generated by the motor, so that the electric storage device is charged with the electric power.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a drive device, and more particularly to a drive device including a motor capable of generating electricity that is connected to a crankshaft of an engine. [Background technology]

[0002] Conventionally, as this type of drive device, a device has been proposed that controls a motor capable of generating electricity using a drive mode in which the engine is driven by power supplied from a power storage device to start the engine, a power generation mode in which the power storage device is charged by power generated during normal engine operation, and a regenerative generation mode in which regenerative generation is performed when the vehicle decelerates (see, for example, Patent Document 1). In this device, in the regenerative generation mode, when regenerative generation starts, the field current of the motor is set to the same maximum value as in the drive mode, which exceeds the maximum value of the field current in the power generation mode, and then the temperature of the motor and each part of the motor is measured, and when at least one of the temperatures of each part exceeds a predetermined threshold, the field current is reduced, thereby increasing the amount of power generated during regeneration and preventing damage to the motor due to overheating. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-081741 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-described drive system, when the power storage device is charged with the generated power obtained by driving the motor as a generator while the engine is outputting power to the drive shaft, the engine is controlled so that a torque corresponding to the torque required for the drive shaft plus a torque corresponding to the regenerative torque of the motor is output from the engine. If the regenerative torque is lost due to a motor failure or other reason, an unexpectedly large torque is output to the drive shaft. When the drive system is installed in a vehicle, the unexpectedly large torque output causes discomfort to the driver.

[0005] The main purpose of the drive device of the present invention is to suppress the inconvenience caused by unexpected excessive torque acting on the drive shaft, which may occur when charging an electric storage device with the generated electricity obtained by driving the motor as a generator while power is being output from the engine to the drive shaft. [Means for solving the problem]

[0006] The driving device of the present invention employs the following means to achieve the above-mentioned main object.

[0007] The drive device of the present invention comprises: an engine that outputs power to a drive shaft; a motor connected to a crankshaft of the engine and capable of generating electricity; a power storage device that exchanges power with the motor; a control device that controls the engine and the motor; A drive device comprising: the control device controls the engine and the motor so that a required torque required for the drive shaft is output to the drive shaft, and a target generated power obtained by upper limiting a required power generation amount based on a power storage rate of the power storage device with an upper power generation amount value based on a rotation speed of the drive shaft is generated by the motor, and the power storage device is charged. It is characterized by:

[0008] In the drive system of the present invention, the engine and the motor are controlled so that the required torque of the drive shaft is output to the drive shaft, and the target power generated by the motor is calculated by limiting the required power generation based on the power storage rate of the power storage device with an upper limit value for power generation based on the rotational speed of the drive shaft, thereby charging the power storage device. Because the target power generation is limited by the upper limit value for power generation based on the rotational speed of the drive shaft, even if the regenerative torque of the motor is lost due to a motor failure or other reason, the magnitude of unexpected excessive torque output to the drive shaft can be suppressed. When the drive system of the present invention is installed in a vehicle, the discomfort felt by the driver due to unexpected excessive torque output to the drive shaft is suppressed by suppressing the magnitude of the unexpected excessive torque. As a result, the inconvenience caused by unexpected excessive torque acting on the drive shaft, which may occur when the power storage device is charged with generated power obtained by driving the motor as a generator while power is being output from the engine to the drive shaft, can be suppressed. It is preferable that the "power generation upper limit value" be an upper limit value that increases as the rotation speed of the drive shaft increases, and when the drive device of the present invention is installed in a vehicle, it is preferable that the upper limit value be an upper limit value that increases as the vehicle speed increases. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing an outline of the configuration of an automobile 20 equipped with a drive unit according to an embodiment of the present invention. [Figure 2] 4 is a flowchart showing an example of torque control during power generation executed by a main ECU 70 of an automobile 20 equipped with the drive device of the embodiment. [Figure 3] FIG. 4 is an explanatory diagram showing an example of a power generation upper limit value setting map. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, an embodiment of the present invention will be described with reference to the accompanying drawings. [Example]

[0011] 1 is a diagram showing an outline of the configuration of an automobile 20 equipped with a drive system according to one embodiment of the present invention. As shown in the figure, the automobile 20 of the embodiment includes an engine 22, a starter 25, a motor 30, an inverter 32, an automatic transmission 40, a high-voltage battery 60, a low-voltage battery 67, a DC / DC converter 68, and a main electronic control unit (hereinafter referred to as "main ECU") 70. The engine 22, motor 30, high-voltage battery 60, and main electronic control unit 70 primarily constitute the drive system.

[0012] The engine 22 is configured as a multi-cylinder (four-cylinder, six-cylinder, etc.) internal combustion engine that uses gasoline, diesel, or the like as fuel supplied from a fuel tank via a fuel supply system and outputs power through intake, compression, expansion (explosive combustion), and exhaust strokes. The operation of the engine 22 is controlled by an engine electronic control unit (hereinafter referred to as "engine ECU") 24.

[0013] Although not shown, the engine ECU 24 is configured as a microprocessor centered on a CPU, and in addition to the CPU, includes a ROM for storing processing programs, a RAM for temporarily storing data, an input / output port, and a communication port. Signals from various sensors required for controlling the operation of the engine 22 are input to the engine ECU 24 via input ports, and various control signals for controlling the operation of the engine 22 are output from the engine ECU 24 via output ports.

[0014] A starter motor 25 for cranking the engine 22 is connected to the crankshaft 23 serving as the output shaft of the engine 22. The input side of a damper 28 serving as a torsion element is also connected to the crankshaft 23 of the engine 22. A pulley 23b is attached to the crankshaft 23 of the engine 22.

[0015] The motor 30 is configured as, for example, a synchronous generator motor. A pulley 30b is attached to the rotating shaft of the motor 30. A belt 31 is wound around the pulley 30b so as to rotate and drive a pulley 23b attached to the crankshaft 23 of the engine 22. The inverter 32 is used to drive the motor 30 and is connected to a high-voltage power line 61. The main ECU 70 controls the switching of multiple switching elements of the inverter 32, thereby rotating and driving the motor 30.

[0016] The automatic transmission 40 includes a torque converter 43, an automatic transmission 45 with, for example, six speeds, and a hydraulic circuit (not shown). The torque converter 43 is configured as a typical fluid-type transmission device and amplifies the torque of the input shaft 41 connected to the rotary shaft of the motor 30 and transmits it to an intermediate rotary shaft 44, which is the input shaft of the automatic transmission 45, or transmits the torque directly without amplifying it. The automatic transmission 45 is connected to the intermediate rotary shaft 44 and to an output shaft 42, which is connected to a drive shaft 46. The automatic transmission 45 has multiple planetary gears and multiple hydraulically driven friction engagement elements (clutches and brakes). The drive shaft 46 is connected to rear wheels 55a, 55b via an axle 56 and a rear differential gear 57. The automatic transmission 45 transmits power between the intermediate rotary shaft 44 and the output shaft 42, forming, for example, forward gears (first through sixth gears) and reverse gears by engaging and disengaging the friction engagement elements.

[0017] High-voltage battery 60 is, for example, a lithium-ion battery or a nickel-metal hydride battery, and is connected to a high-voltage power line 61 that is connected to inverter 32. Low-voltage battery 67 is, for example, a lead battery whose rated voltage is lower than that of high-voltage battery 60, and is connected to a low-voltage power line 66 that is connected to starter motor 25. DC / DC converter 68 is connected to high-voltage power line 61 and low-voltage power line 66. DC / DC converter 68 is controlled by main ECU 70 to step down the power on high-voltage power line 61 and supply the power to low-voltage power line 66.

[0018] Although not shown, the main ECU 70 is configured as a microprocessor centered around a CPU. In addition to the CPU, the main ECU 70 also includes a ROM for storing processing programs, a RAM for temporarily storing data, input / output ports, and communication ports. Signals from various sensors are input to the main ECU 70 via the input ports. Examples of signals input to the main ECU 70 include the rotational position φm of the rotor of the motor 30 from a rotational position sensor (not shown) that detects the rotational position of the rotor of the motor 30, and the rotational speed Np of the drive shaft 46 from a rotational speed sensor 46a attached to the drive shaft 46. Other signals input to the main ECU 70 include the battery temperature Tb from a temperature sensor 60a attached to the high-voltage battery 60, the voltage Vh of the high-voltage battery 60 from a voltage sensor (not shown) attached between the terminals of the high-voltage battery 60, the current Ih of the high-voltage battery 60 from a current sensor (not shown) attached to the output terminals of the high-voltage battery 60, and the voltage Vb of the low-voltage battery 67 from a voltage sensor (not shown) attached between the terminals of the low-voltage battery 67. Further examples include an ignition signal from an ignition switch 80, a shift position SP from a shift position sensor 82 that detects the operating position of a shift lever 81, an accelerator opening Acc from an accelerator pedal position sensor 84 that detects the amount of depression of an accelerator pedal 83, a brake pedal position BP from a brake pedal position sensor 86 that detects the amount of depression of a brake pedal 85, and a vehicle speed V from a vehicle speed sensor 88. The main ECU 70 calculates the power storage percentage SOC based on the voltage Vh of the high-voltage battery 60, the current Ih flowing through the high-voltage battery 60, etc.

[0019] Various control signals are output from the main ECU 70 via an output port. Examples of signals output from the main ECU 70 include a control signal to the starter motor 25, a control signal to the inverter 32, a control signal to the automatic transmission 40, and a control signal to the DC / DC converter 68. The main ECU 70 is connected to the engine ECU 24 via a communication port.

[0020] While the automobile 20 is traveling, the main ECU 70 sets a drive shaft torque demand Td* required of the drive shaft 46 based on the accelerator pedal position Acc and the vehicle speed V, and also sets a motor torque demand Tm* to be output from the motor 30. The main ECU 70 then calculates an effective torque Teg* as the sum of the torque obtained by converting the drive shaft torque Td* to the crankshaft 23 and the torque obtained by converting the motor torque Tm* to the crankshaft 23, and transmits the effective torque Teg* to the engine ECU 24. The engine ECU 24 controls the intake air amount, fuel injection, and ignition so that the received effective torque Teg* is output from the engine 22. The main ECU 70 also controls the switching of the switching elements of the inverter 32 so that the motor torque demand Tm* is output from the motor 30. The main ECU 70 also controls the automatic transmission 40 so that the automatic transmission 40 is in a gear position determined by a gear shift map in which gear positions are divided according to the vehicle speed V and the drive shaft torque demand Td*.

[0021] Next, the operation of the automobile 20 of this embodiment, particularly the operation when charging the high-voltage battery 60 while the automobile is running, will be described. Figure 2 is a flowchart showing an example of torque control during power generation executed by the main ECU 70. This routine is repeatedly executed at predetermined time intervals.

[0022] When power generation torque control is executed, the main ECU 70 first executes a process of inputting data required for control, such as the charge storage rate SOC of the high-voltage battery 60, the vehicle speed V, and the drive shaft torque demand Td* (step S100).

[0023] When the data is input, it is determined whether the power storage rate SOC is less than a threshold value Sref (step S110). The threshold value Sref is a threshold value for determining whether charging of the high-voltage battery 60 is necessary, and may be, for example, 50% or 40%. When it is determined that the power storage rate SOC is equal to or greater than the threshold value Sref, it is determined that charging of the high-voltage battery 60 is unnecessary, and the torque to be output from the engine 22 to the crankshaft 23 is calculated by multiplying the drive shaft required torque Td* by a conversion coefficient km corresponding to the gear position of the automatic transmission 40. This torque is set as the effective torque Teg* and transmitted to the engine ECU 24 (step S120), and the process ends. As described above, when the engine ECU 24 receives the effective torque Teg*, it executes intake air amount control, fuel injection control, and ignition control so that the effective torque Teg* is output from the engine 22.

[0024] When it is determined in step S110 that the power storage ratio SOC is less than the threshold value Sref, a required power generation Pin* to charge the high-voltage battery 60 is set based on the power storage ratio SOC (step S130). In this embodiment, the required power generation Pin* is set by predetermining the relationship between the power storage ratio SOC and the required power generation Pin* and storing it as a required power generation setting map, and deriving the corresponding required power generation Pin* from the map when the power storage ratio SOC is given. Note that the required power generation Pin* is preferably set so that it increases as the power storage ratio SOC decreases, but it may also be a constant value.

[0025] Next, a power generation upper limit value Pinlim is set based on the vehicle speed V (step S140). In this embodiment, the power generation upper limit value Pinlim is set by determining the power generation upper limit value Pinlim from the map when the vehicle speed V is given, based on a relationship between the vehicle speed V and the power generation upper limit value Pinlim that is predetermined and stored as a power generation upper limit value setting map. FIG. 3 shows an example of the power generation upper limit value setting map. In this embodiment, the power generation upper limit value Pinlim tends to increase as the vehicle speed V increases. This is based on the idea that the discomfort felt by the driver due to unexpected excessive torque acting on the drive shaft 46 when regenerative torque is lost from the motor 30 due to a failure of the motor 30 or the like increases as the vehicle speed V decreases. Note that there is a linear relationship between the vehicle speed V and the rotation speed Nd of the drive shaft 46, so setting the power generation upper limit value Pinlim based on the vehicle speed V is equivalent to setting the power generation upper limit value Pinlim based on the rotation speed Nd of the drive shaft 46.

[0026] Once the power generation upper limit value Pinlim has been set in this manner, the required power generation power Pin* is upper-bounded by the power generation upper limit value Pinlim (step S150), and the required power generation power Pin* is divided by the product of the rotation speed Nd of the drive shaft 46 multiplied by a conversion coefficient km corresponding to the gear position of the automatic transmission 40 and a conversion coefficient kp based on the pulleys 23b and 30b to set the motor required torque Tm* (step S160). Once the motor required torque Tm* has been set, the main ECU 70 controls the switching of the switching elements of the inverter 32 so that the motor 30 outputs the motor required torque Tm*.

[0027] Then, the effective torque Teg* is set as the sum of the torque converted to the crankshaft 23 of the drive shaft required torque Td* obtained by multiplying the drive shaft required torque Td* by a conversion coefficient km corresponding to the gear position of the automatic transmission 40, and the torque converted to the crankshaft 23 of the motor required torque Tm* obtained by multiplying the motor required torque Tm* by a conversion coefficient kp based on the pulleys 23b and 30b, and sends this to the engine ECU 24 (step S170), thereby ending this process. As described above, upon receiving the effective torque Teg*, the engine ECU 24 executes intake air amount control, fuel injection control, and ignition control so that the effective torque Teg* is output from the engine 22.

[0028] In an automobile 20 equipped with the drive system of the embodiment described above, the required generation power Pin* to charge the high-voltage battery 60 is set based on the power storage rate SOC, and the required generation power Pin* is upper-limit-guarded by a power generation upper limit value Pinlim set based on the vehicle speed V. Next, the required generation power Pin* is set by dividing the required generation power Pin* by the product of the rotation speed Nd of the drive shaft 46 and a conversion factor km corresponding to the gear position of the automatic transmission 40 and a conversion factor kp based on the pulleys 23b and 30b. The effective torque Teg* is then set as the sum of the torque converted to the crankshaft 23 of the drive shaft required torque Td* obtained by multiplying the drive shaft required torque Td* by the conversion factor km corresponding to the gear position of the automatic transmission 40, and the torque converted to the crankshaft 23 of the motor required torque Tm* obtained by multiplying the motor required torque Tm* by the conversion factor kp based on the pulleys 23b and 30b. In this way, by setting the motor required torque Tm* and the effective torque Teg* while upper limiting the required power generation power Pin* using the power generation upper limit value Pinlim based on the vehicle speed V, it is possible to reduce the unexpected excessive torque acting on the drive shaft 46 when the regenerative torque of the motor 30 is lost due to a failure of the motor 30, etc. As a result, it is possible to reduce inconveniences (such as discomfort felt by the driver) caused by the unexpected excessive torque acting on the drive shaft 46.

[0029] In a vehicle 20 equipped with the drive unit of the embodiment, the required generation power Pin* to charge the high-voltage battery 60 is set based on the power storage ratio SOC, the required generation power Pin* is upper-bounded by a power generation upper limit value Pinlim set based on the vehicle speed V, the motor required torque Tm* is set based on the upper-bounded required generation power Pin*, and the effective torque Teg* of the engine 22 is set based on the motor required torque Tm* and the drive shaft required torque Td*. However, since it is sufficient if the required generation power Pin* is essentially upper-bounded by an upper limit based on the vehicle speed, it is also possible to perform processing in which the engine required torque calculated based on the required generation power Pin* and the drive shaft required torque Td* is upper-bounded by an upper limit based on the vehicle speed. In this case, the required generation power Pin* is calculated based on the upper-bounded engine required torque and the drive shaft required torque Td*, and the motor required torque Tm* is set. Alternatively, the fuel injection quantity required for engine 22 to output the engine required torque calculated based on the required power to be generated Pin* and the drive shaft required torque Td* may be subject to an upper limit guard based on vehicle speed. In this case, the engine torque is calculated from the fuel injection quantity subject to the upper limit guard, and the required power to be generated Pin* is calculated based on this engine torque and the drive shaft required torque Td* to set the motor required torque Tm*. When considering that the drive shaft required torque Td* is output to drive shaft 46, whether an upper limit guard is applied to the engine required torque or the fuel injection quantity, the required power to be generated Pin* will end up being subject to an upper limit guard.

[0030] In the automobile 20 equipped with the drive device of the embodiment, the motor 30 is attached to the crankshaft 23 of the engine 22 via pulley 23b and pulley 30b, but the motor may also be attached to the crankshaft (input shaft) between the engine and the automatic transmission.

[0031] In the embodiment, the drive unit is mounted on an automobile 20, but the drive unit may be mounted on a vehicle other than an automobile, a moving body other than a vehicle, or incorporated into construction equipment or other facilities. In these cases, too, it is possible to reduce unexpected excessive torque acting on the drive shaft when the regenerative torque of the motor is lost due to a motor failure or the like.

[0032] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be explained below. In the embodiment, the engine 22 corresponds to the "engine," the motor 30 corresponds to the "motor," the high-voltage battery 60 corresponds to the "electricity storage device," and the main electronic control unit 70 and the engine electronic control unit 24 correspond to the "control device."

[0033] The correspondence between the main elements of the Examples and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, since the Examples are examples for specifically explaining the mode for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the Examples are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0034] The above describes the form for carrying out the present invention using examples, but the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms within the scope that does not deviate from the gist of the present invention. [Industrial Applicability]

[0035] The present invention can be used in the drive device manufacturing industry and the like. [Explanation of symbols]

[0036] 20 automobile, 22 engine, 23 crankshaft, 23a rotation speed sensor, 23b pulley, 24 engine ECU, 25 starter motor, 28 damper, 30 motor, 30b pulley, 31 belt, 32 inverter, 40 automatic transmission, 41 input shaft, 46a rotation speed sensor, 42 output shaft, 43 torque converter, 44 intermediate rotating shaft, 45 automatic transmission, 46 drive shaft, 55a rear wheel, 56 axle, 57 rear differential gear, 60 high-voltage battery, 61 high-voltage side power line, 66 low-voltage side power line, 67 low-voltage battery, 68 DC / DC converter, 70 main electronic control unit (main ECU), 80 ignition switch, 81 shift lever, 82 shift position sensor, 83 accelerator pedal, 84 accelerator pedal position sensor, 85 Brake pedal, 86 brake pedal position sensor, 88 vehicle speed sensor.

Claims

[Claim 1] an engine that outputs power to a drive shaft; an automatic transmission having an input shaft connected to a crankshaft of the engine and an output shaft connected to the drive shaft; a motor capable of generating electricity, connected to the crankshaft on the side of the engine opposite to the automatic transmission side or between the engine and the automatic transmission; a power storage device that exchanges power with the motor; a control device that controls the engine and the motor; A drive device comprising: When the power storage device is charged while the drive shaft is being driven, the control device controls the engine and the motor so that a required torque required for the drive shaft is output to the drive shaft, and a target power generation amount obtained by upper limiting a power generation required power based on a power storage rate of the power storage device with an upper power generation amount value based on the rotation speed of the drive shaft is generated by the motor, thereby charging the power storage device. A drive device characterized by:

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