JP7703899B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device.

The vehicle in Patent Document 1 is equipped with a chain mechanism for transmitting the driving force of the crankshaft of the internal combustion engine. The chain mechanism includes a drive sprocket, two driven sprockets, a chain, a swing guide, and a chain tensioner. The vehicle also includes an oil pump for supplying oil into the chain tensioner. The drive sprocket is connected to the crankshaft of the internal combustion engine. The drive sprocket rotates integrally with the crankshaft. Each driven sprocket is connected to an intake camshaft and an exhaust camshaft of the internal combustion engine, respectively. The chain is wound around the drive sprocket and the two driven sprockets. The swing guide is located near the chain. The internal combustion engine supports the swing guide so that it can swing. The chain tensioner presses the swing guide against the chain. That is, the chain tensioner applies tension to the chain via the swing guide. The oil pump discharges oil based on the rotation of the crankshaft. The oil discharged from the oil pump is then supplied to the chain tensioner as hydraulic oil. The chain tensioner presses the oscillating guide against the chain with a force that corresponds to the pressure of the supplied oil.

JP 2014-109237 A

Vehicles that are equipped with a motor generator as a drive source in addition to an internal combustion engine are known. Furthermore, such vehicles are capable of running in what is called EV mode. EV mode is a mode in which the vehicle runs by driving the motor generator while stopping the internal combustion engine.

Now, let us assume that a vehicle capable of running in EV mode is equipped with the chain tensioner described in Patent Document 1. Because the internal combustion engine is stopped during EV mode, the oil pump, which is driven by the internal combustion engine, is also stopped. In this state, if a force acts from the chain to the chain tensioner, causing the chain tensioner to operate, oil may leak out of the chain tensioner. And because the oil pump is stopped during EV mode, the leaked oil cannot be resupplied to the chain tensioner. Therefore, after the internal combustion engine starts to drive again, it takes time for the oil pressure in the chain tensioner to reach an appropriate pressure and for sufficient tension to be applied to the chain.

A vehicle control device for solving the above problem is applied to a vehicle including an internal combustion engine as a drive source, a motor generator as a drive source, a battery that supplies power to the motor generator, a drive sprocket fixed to a crankshaft of the internal combustion engine, a driven sprocket to which drive force from the drive sprocket is transmitted, a chain wound around the drive sprocket and the driven sprocket, a swingable guide supported by the drive sprocket, a chain tensioner that presses the swingable guide against the chain, and an oil pump that discharges oil based on the rotation of the crankshaft, and the vehicle A control device that controls the driving mode of the vehicle to either an EV mode in which the motor generator is driven while the internal combustion engine is stopped to drive the vehicle, or a non-EV mode in which the internal combustion engine is driven to drive the vehicle, and the chain tensioner presses the oscillating guide against the chain by the pressure of the oil supplied from the oil pump, and executes a drive process that rotates the crankshaft to drive the oil pump, on the condition that the vehicle is in the EV mode and the pressure of the oil in the chain tensioner is equal to or lower than a predetermined specified pressure.

According to the above configuration, the oil pump is driven when the oil pressure in the chain tensioner is low. This causes the oil discharged from the oil pump to be supplied to the chain tensioner. This prevents the oil pressure in the chain tensioner from dropping too much. As a result, it is possible to prevent the oil pressure in the chain tensioner from taking too long to reach an appropriate pressure after the internal combustion engine starts to drive.

In the above configuration, if the crankshaft continues to rotate repeatedly in the forward and reverse directions for a period of time equal to or longer than a predetermined period of time, the condition may be deemed to be met and the drive process may be executed.

In the above configuration, the state in which the crankshaft repeatedly rotates forward and backward only occurs when the internal combustion engine is stopped. When the crankshaft repeatedly rotates forward and backward, the tension of the chain changes, and a force may act from the chain to the chain tensioner. In other words, when the crankshaft repeatedly rotates forward and backward, the oil pressure in the chain tensioner may decrease. Based on this principle, the above configuration makes it possible to determine that the oil pressure in the chain tensioner has decreased, without measuring the oil pressure in the chain tensioner with a pressure sensor or the like.

In the above configuration, in the drive process, when the oil pressure in the chain tensioner is low, the target value of the pressure of the oil discharged from the oil pump may be set higher than when the oil pressure in the chain tensioner is high. With the above configuration, even if the oil pressure in the chain tensioner is low, the oil pressure in the chain tensioner can be quickly increased.

In the above configuration, when the rotation direction of the crankshaft when the chain runs in the order of the drive sprocket, the oscillating guide, and the driven sprocket is defined as a first rotation direction, and the opposite direction to the first rotation direction is defined as a second rotation direction, the pressure of the oil in the chain tensioner may be estimated based on the integrated value of the rotation amount of the crankshaft in the second rotation direction during the EV mode.

With the above configuration, the integrated value of the force acting on the chain tensioner from the chain can be accurately estimated by the integrated value of the rotation amount of the crankshaft in the second rotation direction. Therefore, the amount of oil that has escaped from the chain tensioner, and therefore the oil pressure inside the chain tensioner, can be accurately estimated.

In the above configuration, the drive process may rotate the crankshaft by operating the internal combustion engine autonomously. With the above configuration, the oil pressure in the chain tensioner can be increased without reducing the charging rate of the battery.

In the above configuration, the drive process may rotate the crankshaft by operating the internal combustion engine autonomously when the charging rate of the battery is less than a predetermined specified value, and rotate the crankshaft by transmitting the driving force of the motor generator to the crankshaft when the charging rate of the battery is equal to or greater than the specified value.

According to the above configuration, the internal combustion engine does not operate autonomously when the battery charge rate is equal to or higher than a specified value. This reduces the chances of the internal combustion engine operating autonomously when the drive process is executed. This reduces the consumption of fuel just to supply oil to the chain tensioner.

FIG. 1 is a schematic diagram of a vehicle. FIG. FIG. 4 is a cross-sectional view of the peripheral configuration of the chain tensioner. 4 is a flowchart showing pressure control.

<Vehicle Mechanical Configuration>
An embodiment of the present invention will now be described with reference to Figures 1 to 4. First, the mechanical configuration of a vehicle 100 to which a control device 90 of the present invention is applied will be described.

As shown in FIG. 1, the vehicle 100 includes an internal combustion engine 10, a power split mechanism 40, a reduction mechanism 50, a first motor generator 61, a second motor generator 62, a transmission mechanism 66, a differential 67, and a number of drive wheels 68 as power transmission paths.

The internal combustion engine 10 has a crankshaft 11 as an output shaft. The crankshaft 11 is connected to the power split mechanism 40. The power split mechanism 40 is a planetary gear mechanism having a sun gear 41, a carrier 42, multiple pinion gears 43, a ring gear 44, and a ring gear shaft 45. The sun gear 41, which is an external gear, and the ring gear 44, which is an internal gear, are positioned coaxially. The sun gear 41 is connected to the ring gear 44 via multiple pinion gears 43. The carrier 42 supports the pinion gear 43 in a state in which it can rotate. The carrier 42 also supports the pinion gear 43 so that it can revolve. In other words, the pinion gear 43 revolves with the rotation of the carrier 42. The carrier 42 is connected to the crankshaft 11. The sun gear 41 is connected to the rotating shaft of the first motor generator 61.

When the driving force of the internal combustion engine 10 is input to the carrier 42, the driving force of the internal combustion engine 10 is distributed to the sun gear 41 side and the ring gear 44 side. Then, when the driving force of the internal combustion engine 10 transmitted via the sun gear 41 is input to the rotating shaft of the first motor generator 61, the first motor generator 61 functions as a generator.

On the other hand, when the first motor generator 61 is made to function as an electric motor, the driving force of the first motor generator 61 is input to the sun gear 41. The driving force of the first motor generator 61 input to the sun gear 41 is then distributed to the carrier 42 side and the ring gear 44 side. When the driving force of the first motor generator 61 transmitted via the carrier 42 is input to the crankshaft 11 of the internal combustion engine 10, the crankshaft 11 of the internal combustion engine 10 rotates. In other words, the first motor generator 61 is able to rotate the crankshaft 11 by transmitting the driving force of the first motor generator 61 to the crankshaft 11.

The ring gear 44 is connected to a ring gear shaft 45. The ring gear shaft 45 rotates integrally with the ring gear 44. The ring gear shaft 45 is connected to a transmission mechanism 66. The transmission mechanism 66 includes, for example, a reduction gear mechanism and an automatic transmission. The transmission mechanism 66 is connected to drive wheels 68 via a differential 67. The differential 67 allows a difference in rotational speed to occur between the left and right drive wheels 68.

The ring gear shaft 45 is connected to the reduction mechanism 50. The reduction mechanism 50 is a planetary gear mechanism having a sun gear 51, a carrier 52, multiple pinion gears 53, a ring gear 54, and a case 55. The sun gear 51, which is an external gear, and the ring gear 54, which is an internal gear, are located on the same axis. The sun gear 51 is connected to the ring gear 54 via multiple pinion gears 53. The carrier 52 supports the pinion gear 53 in a state in which it can rotate. The carrier 52 is fixed to the case 55 of the reduction mechanism 50. In other words, the carrier 52 cannot rotate, and the pinion gear 53 cannot revolve due to the carrier 52. The ring gear 54 is connected to the ring gear shaft 45. The sun gear 51 is connected to the rotating shaft of the second motor generator 62.

The second motor generator 62 functions as a generator when decelerating the vehicle 100, thereby generating a regenerative braking force in the vehicle 100 that corresponds to the amount of power generated by the second motor generator 62.

On the other hand, when the second motor generator 62 is made to function as an electric motor, the driving force of the second motor generator 62 is input to the driving wheels 68 via the reduction mechanism 50, the ring gear shaft 45, the transmission mechanism 66, and the differential 67. Then, the driving force of the second motor generator 62 rotates the driving wheels 68.

As shown in FIG. 1, the vehicle 100 is equipped with a supply passage 76 and an oil pump 77 as mechanisms for supplying oil. Although not shown, the oil pump 77 is connected to the crankshaft 11. The oil pump 77 is driven by the rotation of the crankshaft 11. Therefore, the oil pump 77 is a so-called mechanical oil pump that discharges oil based on the rotation of the crankshaft 11. The supply passage 76 is connected to the oil pump 77. The supply passage 76 supplies the oil discharged from the oil pump 77 to various parts of the internal combustion engine 10.

As shown in FIG. 2, the vehicle 100 includes a chain mechanism 20 for transmitting the driving force of the crankshaft 11 to other devices. The chain mechanism 20 includes a drive sprocket 21, an intake sprocket 22, an exhaust sprocket 23, a chain 24, a fixed guide 25, a swinging guide 26, a cover 27, and a chain tensioner 30.

The drive sprocket 21 is connected to the crankshaft 11. The intake side sprocket 22 is connected to an intake camshaft (not shown) of the internal combustion engine 10. The exhaust side sprocket 23 is connected to an exhaust side camshaft (not shown) of the internal combustion engine 10. The intake camshaft is for opening and closing the intake valve of the internal combustion engine 10. The exhaust camshaft is for opening and closing the exhaust valve of the internal combustion engine 10. The chain 24 is wound around the drive sprocket 21, the intake side sprocket 22, and the exhaust side sprocket 23. Therefore, as shown by the two-dot chain arrow in FIG. 2, when the drive sprocket 21 rotates in the clockwise direction, the chain 24 runs and a driving force is transmitted to the intake side sprocket 22 and the exhaust side sprocket 23. Then, the intake side sprocket 22 and the exhaust side sprocket 23 rotate in the clockwise direction. In this embodiment, the intake side sprocket 22 and the exhaust side sprocket 23 are driven sprockets. In FIG. 2, the drive sprocket 21, the intake sprocket 22, and the exhaust sprocket 23 are illustrated in a simplified manner.

The cover 27 is located near the intake side sprocket 22 and the exhaust side sprocket 23. The cover 27 covers the portion of the chain 24 that is wound around the intake side sprocket 22 and the exhaust side sprocket 23 from the outside of the chain 24.

The fixed guide 25 is located outside the area surrounded by the chain 24 and in the vicinity of the chain 24. The fixed guide 25 is located between the drive sprocket 21 and the exhaust sprocket 23. The fixed guide 25 extends from the drive sprocket 21 toward the exhaust sprocket 23. The fixed guide 25 is fixed to the outer surface of the internal combustion engine 10 by bolts. The fixed guide 25 contacts the chain 24 from outside the area surrounded by the chain 24.

The oscillating guide 26 is located outside the area surrounded by the chain 24 and in the vicinity of the chain 24. The oscillating guide 26 is located between the drive sprocket 21 and the intake side sprocket 22. The oscillating guide 26 includes a guide body 26A, a support protrusion 26B, an abutment protrusion 26C, and a rotating shaft 26D. The guide body 26A extends from the drive sprocket 21 toward the intake side sprocket 22. The guide body 26A has a generally bow-shaped shape with the central portion in the longitudinal direction curved so as to be convex toward the chain 24. The support protrusion 26B is located at the end of the guide body 26A close to the drive sprocket 21. The support protrusion 26B protrudes in a direction away from the chain 24. The rotating shaft 26D penetrates the support protrusion 26B. The rotating shaft 26D is fixed to the internal combustion engine 10. The support protrusion 26B and the guide body 26A can swing around the pivot shaft 26D. The abutment protrusion 26C is located closer to the intake sprocket 22 than the longitudinal center of the guide body 26A. The abutment protrusion 26C protrudes in a direction away from the chain 24. As shown in FIG. 3, the protruding end surface of the abutment protrusion 26C is curved so that the center portion of the protruding end surface is recessed.

As shown by the dashed double-dashed arrow in FIG. 2, when the internal combustion engine 10 is driven and the crankshaft 11 rotates clockwise, the chain 24 runs in the order of the drive sprocket 21, the oscillating guide 26, and the intake sprocket 22. Therefore, in this embodiment, the forward rotation direction of the crankshaft 11 is the first rotation direction. Also, the opposite direction to the first rotation direction, i.e., the reverse rotation direction of the crankshaft 11, is the second rotation direction.

As shown in FIG. 2, the chain tensioner 30 is located on the opposite side of the oscillating guide 26 from the chain 24. As shown in FIG. 3, the chain tensioner 30 includes a housing 31, a plunger 32, a biasing spring 33, a check valve mechanism 34, an upper flange 36, and a lower flange 37.

As shown in FIG. 3, the housing 31 is substantially cylindrical. One end of the housing 31 is closed. The opening of the housing 31 faces the abutment protrusion 26C. The housing 31 has an internal space 31A, an expanded diameter space 31B, and a supply hole 31C as spaces within the housing 31. The internal space 31A extends from the opening of the housing 31 toward the bottom surface. The internal space 31A is a substantially cylindrical space. The expanded diameter space 31B is connected to the substantially central portion of the internal space 31A in the axial direction. The expanded diameter space 31B surrounds the internal space 31A in the circumferential direction. In other words, the expanded diameter space 31B is a substantially annular space. The supply hole 31C penetrates from the expanded diameter space 31B to the outer circumferential surface of the housing 31. The supply hole 31C is connected to the supply passage 76.

The upper flange 36 protrudes upward from the outer circumferential surface of the housing 31. The upper flange 36 is fixed to the outer surface of the internal combustion engine 10 by bolts. The lower flange 37 protrudes downward from the outer circumferential surface of the housing 31. The lower flange 37 is fixed to the outer surface of the internal combustion engine 10 by bolts.

The plunger 32 is generally cylindrical. The outer diameter of the plunger 32 is slightly smaller than the inner diameter of the internal space 31A in the housing 31. The plunger 32 is located in the internal space 31A in the housing 31. A portion of the plunger 32 including the first end protrudes from the internal space 31A. The end face including the first end of the plunger 32 abuts against the abutment protrusion 26C of the swing guide 26. The end face including the first end of the plunger 32 is curved so that the central portion protrudes. In addition, a hydraulic chamber 30A to which oil is supplied is defined between the end face including the second end of the plunger 32 and the bottom surface of the internal space 31A in the housing 31. The chain tensioner 30 also functions as an oil damper by the oil supplied to the hydraulic chamber 30A.

The plunger 32 has a first space 32A, a second space 32B, a connection hole 32C, and an introduction hole 32D as spaces within the plunger 32. The second space 32B, the connection hole 32C, and the first space 32A are arranged in this order from the second end to the first end of the plunger 32. The second space 32B is a space having an approximately cylindrical shape. The second space 32B is open to the hydraulic chamber 30A. The connection hole 32C is connected to the second space 32B. The connection hole 32C is a space having an approximately cylindrical shape. The inner diameter of the connection hole 32C is smaller than the inner diameter of the second space 32B. The first space 32A is connected to the connection hole 32C. The first space 32A is a space having an approximately cylindrical shape. The inner diameter of the first space 32A is larger than the inner diameter of the connection hole 32C. The introduction hole 32D is connected to the first space 32A. The introduction hole 32D reaches the outer peripheral surface of the plunger 32.

The biasing spring 33 is located between the housing 31 and the plunger 32. The biasing spring 33 is compressed. A first end of the biasing spring 33 is in contact with the bottom surface of the housing 31. A part of the biasing spring 33, including the second end, is located in the second space 32B of the plunger 32. The biasing spring 33 is in contact with the bottom surface of the plunger 32 that defines the second space 32B. The biasing spring 33 biases the plunger 32 toward the abutment protrusion 26C of the swing guide 26.

The check valve mechanism 34 is located in the second space 32B of the plunger 32. The check valve mechanism 34 is attached to the bottom surface that divides the second space 32B. The check valve mechanism 34 regulates the flow of oil between the first space 32A and the second space 32B according to the oil pressure in the first space 32A and the second space 32B. Specifically, when the oil pressure in the first space 32A is higher than the oil pressure in the second space 32B, the check valve mechanism 34 allows the oil to flow from the first space 32A to the second space 32B through the connection hole 32C. On the other hand, when the oil pressure in the first space 32A is equal to or lower than the oil pressure in the second space 32B, the check valve mechanism 34 regulates the flow of oil from the second space 32B to the first space 32A through the connection hole 32C. Then, the plunger 32 protrudes relative to the housing 31 in response to the pressure of the oil supplied to the second space 32B. As a result, the chain tensioner 30 presses the oscillating guide 26 against the chain 24 with a force corresponding to the pressure of the oil supplied to the second space 32B.

<Vehicle Electrical Configuration>
Next, the electrical configuration of the vehicle 100 will be described.
1 , the vehicle 100 includes, as devices for transferring electric power, a first inverter 71, a second inverter 72, and a battery 73. The first inverter 71 adjusts the amount of electric power transferred between the first motor generator 61 and the battery 73. The second inverter 72 adjusts the amount of electric power transferred between the second motor generator 62 and the battery 73.

As shown in FIG. 1, the vehicle 100 is equipped with a crank angle sensor 81, an accelerator opening sensor 83, a vehicle speed sensor 84, a current sensor 86, a voltage sensor 87, a temperature sensor 88, and an accelerator pedal 89. The crank angle sensor 81 is located near the crankshaft 11. The crank angle sensor 81 detects a crank angle SC, which is the rotation angle of the crankshaft 11. The accelerator opening sensor 83 is located near an accelerator pedal 89 operated by the driver. The accelerator opening sensor 83 detects an accelerator opening ACC, which is the amount of operation of the accelerator pedal 89 operated by the driver. The vehicle speed sensor 84 detects a vehicle speed SP, which is the speed of the vehicle 100. The current sensor 86 detects a current IB, which is a current input/output to the battery 73. The voltage sensor 87 detects a voltage VB, which is a terminal voltage of the battery 73. The temperature sensor 88 detects a battery temperature TB, which is the temperature of the battery 73.

The vehicle 100 is equipped with a control device 90. The control device 90 obtains a signal indicating the crank angle SC from the crank angle sensor 81. The control device 90 obtains a signal indicating the accelerator opening ACC from the accelerator opening sensor 83. The control device 90 obtains a signal indicating the vehicle speed SP from the vehicle speed sensor 84. The control device 90 obtains a signal indicating the current IB from the current sensor 86. The control device 90 obtains a signal indicating the voltage VB from the voltage sensor 87. The control device 90 obtains a signal indicating the battery temperature TB from the temperature sensor 88.

The control device 90 calculates the engine speed NE, which is the number of revolutions per unit time of the crankshaft 11, based on the crank angle SC. The control device 90 calculates the charging rate SOC of the battery 73 based on the current IB, the voltage VB, and the battery temperature TB. Specifically, the control device 90 calculates the charging rate SOC based on the following formula:

Equation (1): Charging rate SOC [%] = remaining capacity of battery 73 [Ah] / fully charged capacity of battery 73 [Ah] × 100 [%]
In the above formula (1), the full charge capacity is calculated based on, for example, the voltage VB and the battery temperature TB of the battery 73. The remaining capacity is calculated based on, for example, the voltage VB and the current IB of the battery 73.

The control device 90 controls the charging of the battery 73. This charging control controls the charging rate SOC of the battery 73 to be in a range between the upper charging rate limit SOCH and the lower charging rate limit SOCL. An example of the upper charging rate limit SOCH is 60 to 80%. An example of the lower charging rate limit SOCL is 20 to 30%.

The control device 90 also calculates the vehicle required output, which is the required value of the output required for the vehicle 100 to travel, based on the accelerator opening ACC and the vehicle speed SP. The control device 90 determines the torque distribution of the internal combustion engine 10, the first motor generator 61, and the second motor generator 62 based on the vehicle required output. The control device 90 controls the output of the internal combustion engine 10 and the power running and regeneration of the first motor generator 61 and the second motor generator 62 based on the torque distribution of the internal combustion engine 10, the first motor generator 61, and the second motor generator 62.

The control device 90 performs various controls such as adjusting the intake air amount, adjusting the fuel injection amount, and adjusting the ignition timing in the internal combustion engine 10 by outputting a control signal to the internal combustion engine 10. The control device 90 also outputs a control signal to the first inverter 71 when controlling the first motor generator 61. The control device 90 controls the first motor generator 61 by adjusting the amount of power exchanged between the first motor generator 61 and the battery 73 via the first inverter 71. The control device 90 also outputs a control signal to the second inverter 72 when controlling the second motor generator 62. The control device 90 controls the second motor generator 62 by adjusting the amount of power exchanged between the second motor generator 62 and the battery 73 via the second inverter 72.

When the vehicle 100 is traveling, the control device 90 selects either the EV mode or the HV mode as the traveling mode of the vehicle 100. Here, the EV mode is a traveling mode in which the vehicle 100 is traveled by driving at least one of the first motor generator 61 and the second motor generator 62 while stopping the internal combustion engine 10. Therefore, in the EV mode, the vehicle 100 is traveled by the driving force of the first motor generator 61 and the driving force of the second motor generator 62. Also, the HV mode is a traveling mode of the vehicle 100 in which the internal combustion engine 10 is driven in addition to the first motor generator 61 and the second motor generator 62. Therefore, in the HV mode, the vehicle 100 is traveled by the driving force of the internal combustion engine 10 in addition to the driving force of the first motor generator 61 and the second motor generator 62. In this embodiment, the HV mode is an example of a non-EV mode.

The control device 90 selects the EV mode, for example, when there is sufficient margin in the charging rate SOC of the battery 73 and the above-mentioned vehicle required output is small. Examples of small vehicle required output include when the vehicle 100 starts moving and when the vehicle 100 is running under light load with low acceleration. On the other hand, the control device 90 selects the HV mode, for example, when there is not sufficient margin in the charging rate SOC of the battery 73.

The control device 90 may be configured as a circuit including one or more processors that execute various processes according to a computer program (software). The control device 90 may also be configured as a circuit including one or more dedicated hardware circuits, such as an application specific integrated circuit (ASIC), that execute at least some of the various processes, or a combination thereof. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions that are configured to cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes any medium that can be accessed by a general-purpose or dedicated computer.

<Pressure control>
Next, a description will be given of the pressure control performed by the control device 90. In this embodiment, the pressure control is a control for suppressing an excessive decrease in pressure in the hydraulic chamber 30A of the chain tensioner 30 during the EV mode. When the EV mode is selected as the driving mode of the vehicle 100, the control device 90 repeatedly executes the pressure control.

As shown in FIG. 4, when the control device 90 starts pressure control, it proceeds to the process of step S11. In step S11, the control device 90 calculates the fluctuation amount XA of the crankshaft 11. Here, in the EV mode, since the internal combustion engine 10 is stopped, the crankshaft 11 may rotate slightly forward or backward, that is, the angular position of the crankshaft 11 may fluctuate. Therefore, the control device 90 calculates the magnitude of the fluctuation of the angular position of the crankshaft 11 as the fluctuation amount XA. Specifically, in step S11, the control device 90 acquires the transition of the crank angle SC from the processing time of step S11 until a certain period ago. Then, the control device 90 calculates the value obtained by subtracting the minimum value from the maximum value of the transition of the crank angle SC as the fluctuation amount XA. Note that when the crankshaft 11 rotates forward, the crank angle SC gradually becomes a larger value within a range of 0 degrees or more and less than 720 degrees. Therefore, the fluctuation amount XA is calculated as a positive value. The control device 90 then proceeds to step S12.

In step S12, the control device 90 judges whether the fluctuation amount XA is equal to or greater than a predetermined judgment value. Here, the judgment value is set in advance by experiment or the like as a value for judging the fluctuation of the angular position of the crankshaft 11. The judgment value is, for example, several degrees to several tens of degrees. In this embodiment, the process of step S12 is an example of a process for judging whether the crankshaft 11 is in a state of forward and reverse rotation. In step S12, if the control device 90 judges that the fluctuation amount XA is less than the judgment value (S12: NO), the control device 90 ends the current pressure control and proceeds to step S11 again. Note that, if the control device 90 judges negative in step S12, it resets the fluctuation period XB described later. On the other hand, in step S12, if the control device 90 judges that the fluctuation amount XA is equal to or greater than the judgment value (S12: YES), the control device 90 proceeds to step S13.

In step S13, the control device 90 starts timing the variable period XB. The variable period XB is the period during which the crankshaft 11 continues to rotate repeatedly forward and backward. Specifically, if the variable period XB is not being timed at the time of processing step S13, the control device 90 starts timing the variable period XB. Furthermore, if the variable period XB is being timed at the time of processing step S13, the control device 90 continues timing the variable period XB.

In step S14, the control device 90 determines whether the fluctuation period XB is equal to or greater than a predetermined period. Here, the predetermined period is determined, for example, as follows. Specifically, when setting the predetermined period, the minimum value of the oil pressure in the chain tensioner 30 that allows the chain tensioner 30 to apply sufficient tension to the chain 24 is obtained by experiment or the like. In addition, a value that is a certain value higher than the minimum value of the oil pressure in the chain tensioner 30 is set as the allowable pressure. Furthermore, the average value of the oil pressure in the chain tensioner 30 that is higher than the allowable pressure and is used when the vehicle 100 is running in HV mode is set as the reference pressure. In addition, the period during which the oil pressure in the chain tensioner 30 changes from the reference pressure to the allowable pressure due to the fluctuation in the angular position of the crankshaft 11 during the EV mode is obtained by experiment or the like. The period during which the oil pressure in the chain tensioner 30 changes from the reference pressure to the allowable pressure is set as the predetermined period. The predetermined period is, for example, several tens of minutes to several tens of minutes. In this embodiment, the process of step S14 is an example of a process for determining whether the oil pressure in the chain tensioner 30 is equal to or lower than a predetermined specified pressure. Also, the above-mentioned allowable pressure is an example of a predetermined specified pressure.

If the control device 90 determines in step S14 that the fluctuation period XB is less than the predetermined period (S14: NO), the control device 90 ends the current pressure control and proceeds to step S11 again. On the other hand, if the control device 90 determines in step S14 that the fluctuation period XB is equal to or greater than the predetermined period (S14: YES), the control device 90 first resets the fluctuation period XB. Then, the control device 90 proceeds to step S21. In this way, the control device 90 proceeds to step S21 on the condition that the vehicle is in EV mode and the oil pressure in the chain tensioner 30 is equal to or less than the predetermined pressure.

In step S21, the control device 90 calculates an integrated value XC of the reverse rotation amount of the crankshaft 11. Specifically, the control device 90 acquires the transition of the crank angle SC from the processing time of step S14 until a predetermined period ago. The predetermined period used here is the same period as the predetermined period used as the threshold value in step S14. The control device 90 also identifies all the maximum and minimum values of the crank angle SC for the transition of the crank angle SC described above. Furthermore, for each maximum and minimum value of the crank angle SC, the control device 90 calculates the reverse rotation amount by subtracting the minimum value of the crank angle SC next to the maximum value from the maximum value of the crank angle SC. The control device 90 then calculates the integrated value XC by accumulating all the reverse rotation amounts calculated as described above. The calculated integrated value XC is a positive value. The control device 90 then proceeds to step S22.

In step S22, the control device 90 calculates the amount of oil XD that has leaked out from the chain tensioner 30 based on the integrated value XC of the amount of reverse rotation of the crankshaft 11. Specifically, the control device 90 calculates the amount of oil leaked out XD to be a larger value as the integrated value XC of the amount of reverse rotation of the crankshaft 11 is larger. The control device 90 then proceeds to step S23.

In step S23, the control device 90 estimates the estimated pressure XE, which is an estimate of the pressure of the oil in the chain tensioner 30, based on the amount of oil that has leaked XD. Specifically, the control device 90 calculates the estimated pressure XE to be a lower value as the amount of oil that has leaked XD increases. The control device 90 then advances the process to step S24.

In step S24, the control device 90 calculates the target pressure Z, which is the target value of the pressure of the oil discharged from the oil pump 77, based on the estimated pressure XE. Specifically, the lower the estimated pressure XE, the higher the target pressure Z calculated by the control device 90. In other words, the larger the integrated value XC of the reverse rotation amount of the crankshaft 11, the higher the target pressure Z calculated by the control device 90. Also, as described above, the forward rotation direction of the crankshaft 11 shown by the two-dot chain arrow in FIG. 2 is the first rotation direction, and the reverse direction of the crankshaft 11 is the second rotation direction. Therefore, the process of step S24 is an example of a process of estimating the target pressure Z based on the integrated value of the rotation amount of the crankshaft 11 in the second rotation direction during the EV mode. The control device 90 then proceeds to step S30.

In step S30, the control device 90 determines whether the charging rate SOC of the battery 73 is equal to or greater than a predetermined specified value. Here, the specified value is set as a value for determining whether the charging rate SOC of the battery 73 has sufficient margin. In this embodiment, the specified value is a value greater than the charging rate lower limit SOCL. An example of the specified value is 40%. In step S30, if the control device 90 determines that the charging rate SOC of the battery 73 is equal to or greater than the specified value (S30: YES), the process proceeds to step S31.

In step S31, the control device 90 rotates the crankshaft 11 by the first motor generator 61. Specifically, the control device 90 controls the first motor generator 61 via the first inverter 71. Then, the driving force of the first motor generator 61 is transmitted to the crankshaft 11 via the power split mechanism 40. As a result, the crankshaft 11 rotates forward. At this time, the control device 90 controls the first motor generator 61 so that the rotation speed of the crankshaft 11, i.e., the engine rotation speed NE, increases as the target pressure Z increases. Therefore, the amount of oil discharged from the oil pump 77 increases as the target pressure Z increases. The control device 90 then advances the process to step S41.

On the other hand, in step S30, when the control device 90 determines that the charging rate SOC of the battery 73 is less than the specified value (S30: NO), the control device 90 proceeds to step S32.
In step S32, the control device 90 rotates the crankshaft 11 by operating the internal combustion engine 10 autonomously. At this time, the control device 90 controls the internal combustion engine 10 so that the engine rotation speed NE increases as the target pressure Z increases. Therefore, the amount of oil discharged from the oil pump 77 increases as the target pressure Z increases. Here, the autonomous operation of the internal combustion engine 10 refers to an operating state in which the crankshaft 11 can be continuously rotated only by the driving force caused by the combustion of fuel in the cylinders of the internal combustion engine 10. Note that the process of step S32 temporarily switches the driving mode of the vehicle 100 from the EV mode to the HV mode. After that, the control device 90 advances the process to step S41.

In step S41, the control device 90 calculates the rotation period XT of the crankshaft 11. Specifically, the control device 90 calculates the elapsed time from the start of the processing of step S31 or the processing of step S32 to the processing point of step S41 as the rotation period XT of the crankshaft 11. The control device 90 then advances the process to step S42.

In step S42, the control device 90 determines whether the rotation period XT of the crankshaft 11 is equal to or longer than a predetermined specified period. Here, the specified period is determined, for example, as follows. First, the oil pressure in the chain tensioner 30 at the time when the process of step S31 or the process of step S32 is started is the above-mentioned allowable pressure. Then, the period from the start of the process of step S31 or the process of step S32 until the oil pressure in the chain tensioner 30 becomes a reference pressure higher than the above-mentioned allowable pressure is set as the specified period. As described above, the reference pressure is a pressure higher than the above-mentioned allowable pressure and is the average value of the oil pressure in the chain tensioner 30 when the vehicle 100 is running in HV mode. In step S42, if the control device 90 determines that the rotation period XT of the crankshaft 11 is less than the specified period (S42: NO), the process returns to step S41. On the other hand, in step S42, if the control device 90 determines that the rotation period XT of the crankshaft 11 is equal to or longer than the specified period (S42: YES), the process proceeds to step S43.

In step S43, the control device 90 stops the rotation of the crankshaft 11. Specifically, if the crankshaft 11 was rotated by the first motor generator 61 in step S31, the control device 90 controls the first motor generator 61 so that the driving force of the first motor generator 61 is not transmitted to the crankshaft 11. As a result, the rotation of the crankshaft 11 stops. On the other hand, if the crankshaft 11 was rotated by operating the internal combustion engine 10 independently in step S32, the control device 90 stops the rotation of the crankshaft 11 by stopping the internal combustion engine 10. In this case, the driving mode of the vehicle 100 returns from the HV mode to the EV mode by the process of step S43. Thereafter, the control device 90 ends the current pressure control and proceeds to the process of step S11 again. In this embodiment, the processes of steps S21 to S43 are an example of a drive process.

<Action of this embodiment>
During the EV mode of the vehicle 100, the internal combustion engine 10 stops, and the oil pump 77, which is driven by the internal combustion engine 10, also stops. Therefore, oil from the oil pump 77 is not supplied to the chain tensioner 30. Meanwhile, during the EV mode of the vehicle 100, the driving force of the second motor generator 62 may be transmitted to the crankshaft 11 via the reduction mechanism 50 and the power split mechanism 40. When the crankshaft 11 rotates forward and backward, the chain 24 runs, causing the tension of the chain 24 to change. Therefore, a force acts on the chain tensioner 30 from the chain 24 via the swing guide 26. Then, the oil in the chain tensioner 30 is discharged. Therefore, the pressure of the oil in the chain tensioner 30 decreases due to the crankshaft 11 continuing to rotate forward and backward.

<Effects of this embodiment>
(1) In this embodiment, when the vehicle 100 is in the EV mode and the oil pressure in the chain tensioner 30 is equal to or lower than a predetermined specified pressure, the crankshaft 11 is rotated to drive the oil pump 77. When the oil pump 77 is driven in this manner, oil from the oil pump 77 is supplied to the chain tensioner 30. Because the oil from the oil pump 77 is supplied to the chain tensioner 30 in this manner, an excessive drop in the oil pressure in the chain tensioner 30 is suppressed. This makes it possible to suppress the time required for the oil pressure in the chain tensioner 30 to reach an appropriate pressure after the internal combustion engine 10 starts to drive. As a result, it is also possible to suppress the time required for sufficient tension to be applied to the chain 24.

(2) In the vehicle 100, the state in which the crankshaft 11 repeatedly rotates forward and backward occurs only when the internal combustion engine 10 is stopped. As described above, the oil pressure in the chain tensioner 30 decreases as the crankshaft 11 continues to rotate forward and backward.

Therefore, in this embodiment, when the fluctuation period XB, which is the period during which the crankshaft 11 continues to rotate forward and backward repeatedly, is equal to or longer than a predetermined period, the crankshaft 11 is rotated to drive the oil pump 77. That is, in this embodiment, in the above case, it is assumed that the conditions are met that the vehicle 100 is in EV mode and the oil pressure in the chain tensioner 30 is equal to or lower than a predetermined specified pressure. With this configuration, based on the above principle, it is possible to determine that the oil pressure in the chain tensioner 30 has dropped, for example, without measuring the oil pressure in the chain tensioner 30 with a pressure sensor or the like.

(3) In this embodiment, the lower the estimated pressure XE, which is the estimated value of the pressure of the oil in the chain tensioner 30, the higher the target pressure Z, which is the target value of the pressure of the oil discharged from the oil pump 77, is calculated. And, the higher the target pressure Z, the higher the rotational speed of the crankshaft 11 becomes, and thus the greater the amount of oil discharged from the oil pump 77. As a result, even if the pressure of the oil in the chain tensioner 30 is low, the pressure of the oil in the chain tensioner 30 can be quickly increased by driving the oil pump 77.

(4) As shown by the dashed-dotted arrow in FIG. 2, when the crankshaft 11 rotates clockwise in FIG. 2, the chain 24 runs in the order of the drive sprocket 21, the oscillating guide 26, the intake side sprocket 22, and the exhaust side sprocket 23. At this time, the portion of the chain 24 between the exhaust side sprocket 23 and the drive sprocket 21 is pulled by the drive sprocket 21. Therefore, the tension of the portion of the chain 24 between the exhaust side sprocket 23 and the drive sprocket 21 is relatively high. On the other hand, the tension of the portion of the chain 24 between the drive sprocket 21 and the intake side sprocket 22 is relatively low because the chain 24 is sent out from the drive sprocket 21.

2, the chain 24 runs in the order of the intake side sprocket 22, the swing guide 26, the drive sprocket 21, and the exhaust side sprocket 23. At this time, the tension of the chain 24 between the drive sprocket 21 and the exhaust side sprocket 23 is relatively low because the chain 24 is sent out from the drive sprocket 21. On the other hand, the chain 24 between the intake side sprocket 22 and the drive sprocket 21 is pulled by the drive sprocket 21. Therefore, the tension of the chain 24 between the intake side sprocket 22 and the drive sprocket 21 is relatively high. And when the tension of the chain 24 between the intake side sprocket 22 and the drive sprocket 21 increases, there is a high possibility that oil will leak out of the chain tensioner 30. Therefore, even if the period during which the crankshaft 11 continues to rotate forward and backward repeatedly is the same, the greater the cumulative value XC of the amount of reverse rotation of the crankshaft 11, the more likely it is that force will act on the chain tensioner 30. As a result, the oil pressure in the chain tensioner 30 will be more likely to decrease.

In this regard, in this embodiment, the larger the integrated value XC of the reverse rotation amount of the crankshaft 11, the lower the estimated pressure XE, which is the estimated value of the oil pressure in the chain tensioner 30, is calculated to be. In other words, the larger the integrated value XC of the reverse rotation amount of the crankshaft 11, the easier it is for force to act on the chain tensioner 30, so the estimated pressure XE is calculated to be a lower value. This allows the estimated pressure XE to be estimated accurately.

(5) In this embodiment, when the charging rate SOC of the battery 73 is equal to or higher than a specified value, the driving force of the first motor generator 61 is transmitted to the crankshaft 11 to rotate the crankshaft 11. In other words, when the charging rate SOC of the battery 73 is equal to or higher than a specified value, the internal combustion engine 10 does not operate independently due to the low oil pressure in the chain tensioner 30. Therefore, the internal combustion engine 10 is less likely to operate independently in order to rotate the crankshaft 11 and drive the oil pump 77. This makes it possible to prevent fuel from being consumed in the internal combustion engine 10 just to supply oil to the chain tensioner 30.

<Example of change>
This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

- In the above embodiment, the drive source for driving the oil pump 77 in the drive process can be changed as appropriate. For example, the control device 90 may rotate the crankshaft 11 by operating the internal combustion engine 10 independently, regardless of the charging rate SOC of the battery 73. In this case, the pressure inside the chain tensioner 30 can be increased without lowering the charging rate SOC of the battery 73. In addition, since control based on the charging rate SOC of the battery 73, etc. is no longer necessary, the series of pressure control processes can be simplified.

- For example, the control device 90 may rotate the crankshaft 11 by driving the first motor generator 61 regardless of the charging rate SOC of the battery 73. Since the power of the battery 73 is used in EV mode, it can be expected that the charging rate SOC of the battery 73 is secured to a certain degree when pressure control is executed. Also, since the period during which the oil pump 77 is driven in the drive process is relatively short, the impact of driving the first motor generator 61 regardless of the charging rate SOC of the battery 73 is small.

- In the above embodiment, the vehicle 100 does not need to have two motor generators, but only needs to have at least one motor generator. In addition, a so-called series hybrid vehicle is known as such a vehicle 100, in which an internal combustion engine, a clutch, a motor generator, and driving wheels are connected in that order. In this vehicle 100, when performing the drive process, the clutch may be engaged, and the driving force of the motor generator may be transmitted to the crankshaft of the internal combustion engine via the clutch.

- In the above embodiment, the conditions for executing the drive process may be changed. For example, when the duration of the EV mode of the vehicle 100 is equal to or longer than a predetermined period, the control device 90 may execute the drive process assuming that the conditions for executing the drive process are satisfied. In other words, it is not essential to determine whether the crankshaft 11 is rotating forward and backward, and to time that period.

- In the above embodiment, the fluctuation period XB is calculated as the period during which the crankshaft 11 continues to rotate in the normal and reverse directions, but this is not limited to the above. For example, the fluctuation period XB may be calculated as the accumulated period during which the crankshaft 11 repeats rotating in the normal and reverse directions in one EV mode. In the case of this modified example, the pressure of the oil in the chain tensioner 30 can be accurately estimated even in cases where, for example, the crankshaft 11 rotates in the normal and reverse directions, then stops rotating completely, and then rotates in the normal and reverse directions again.

- In the above embodiment, the configuration for estimating the estimated pressure XE, which is an estimated value of the pressure of the oil in the chain tensioner 30, may be changed. For example, depending on the configuration of the chain mechanism 20, when the crankshaft 11 rotates in reverse, the chain 24 runs in the order of the drive sprocket 21, the oscillating guide 26, and the intake side sprocket 22. In this configuration, when the crankshaft 11 rotates forward, the force acting on the chain tensioner 30 from the chain 24 via the oscillating guide 26 tends to be larger than when the crankshaft 11 rotates in reverse. Therefore, in the above configuration, the control device 90 may calculate the estimated pressure XE based on the integrated value of the forward rotation amount of the crankshaft 11. Note that in the above configuration, the reverse direction of the crankshaft 11 is the first rotation direction, and the forward rotation direction of the crankshaft 11 is the second rotation direction.

- Also, for example, the control device 90 may calculate the estimated pressure XE based on both the integrated value XC of the reverse rotation amount of the crankshaft 11 and the integrated value of the forward rotation amount of the crankshaft 11. As a specific example, the control device 90 may calculate the estimated pressure XE to be a lower value as the sum of the integrated value XC of the reverse rotation amount of the crankshaft 11 and the integrated value of the forward rotation amount of the crankshaft 11 increases.

- In the above embodiment, the configuration for calculating the target pressure Z may be changed. For example, the lower the estimated pressure XE, the higher the target pressure Z calculated by the control device 90; however, the target pressure Z may be increased in stages. As a specific example, the control device 90 determines whether the estimated pressure XE is less than a predetermined pressure. Then, when the control device 90 determines that the estimated pressure XE is less than the predetermined pressure, the control device 90 may calculate the target pressure Z to be a higher value than when the control device 90 determines that the estimated pressure XE is equal to or greater than the predetermined pressure.

-Also, for example, the control device 90 may set a constant target pressure Z regardless of the estimated pressure XE. In this case, the processes of steps S21 to S23 can be omitted in the pressure control.

- In the above embodiment, the pressure of the oil in the chain tensioner 30 does not need to be estimated. As a specific example, the vehicle 100 may be equipped with a pressure sensor that detects the pressure of the oil in the chain tensioner 30.

- In the above embodiment, the configuration for adjusting the amount of oil discharged from the oil pump 77 during the drive process may be changed. For example, the control device 90 may set the rotational speed of the crankshaft 11 during the drive process to a constant value regardless of the target pressure Z.

- In the above embodiment, the configuration of the oil pump 77 may be changed. For example, the oil pump 77 may be an oil pump that can change the amount of oil discharged during one rotation of the crankshaft 11 by controlling an adjustment valve to adjust the capacity of the oil pump 77, i.e., a variable capacity pump. In this configuration, it is preferable that the control device 90 increases the amount of oil discharged from the oil pump 77 during one rotation of the crankshaft 11 as the target pressure Z increases. In this case, it is acceptable for the rotational speed of the crankshaft 11 in the drive process to be a constant value regardless of the target pressure Z.

LIST OF SYMBOLS 10...INTERNAL COMBUSTION ENGINE 11...CRANKSHAFT 20...CHAIN MECHANISM 21...DRIVE SPROCKET 22...INHALEUT SPROCKET 23...EXHAUST SPROCKET 24...CHAIN 25...FIXED GUIDE 26...OSCILLATING GUIDE 27...COVER 30...CHAIN TENSIONER 30A...HYDRAULIC CHAMBER 31...HOUSING 32...PLUNGER 33...PRESSURE SPRING 34...CHECK VALVE MECHANISM 40...POWER SPLIT MECHANISM 50...REDUCTION MECHANISM 61...FIRST MOTOR-GENERATOR 62...SECOND MOTOR-GENERATOR 66...TRANSMISSION MECHANISM 67...DIFFERENTIAL 68...DRIVE WHEEL 71...FIRST INVERTER 72...SECOND INVERTER 73...BATTERY 76...SUPPLY PASSAGE 77...OIL PUMP 90...CONTROL DEVICE 100...VEHICLE

Claims (6)

An internal combustion engine as a drive source;
A motor generator as a drive source;
a battery for supplying power to the motor generator;
a drive sprocket fixed to a crankshaft of the internal combustion engine;
a driven sprocket to which a driving force is transmitted from the driving sprocket;
a chain wound around the driving sprocket and the driven sprocket;
A swing guide supported to be swingable;
a chain tensioner that presses the swing guide against the chain;
an oil pump that discharges oil based on rotation of the crankshaft;
Applies to vehicles equipped with
A control device that controls a driving mode of the vehicle to either an EV mode in which the vehicle is driven by driving the motor generator while stopping the internal combustion engine, or a non-EV mode in which the vehicle is driven by driving the internal combustion engine,
the chain tensioner presses the swing guide against the chain by the pressure of oil supplied from the oil pump,
A vehicle control device that executes a drive process to rotate the crankshaft and drive the oil pump, when the vehicle is in the EV mode and the pressure of the oil in the chain tensioner is equal to or lower than a predetermined specified pressure. 2. The vehicle control device according to claim 1, wherein when a period during which the crankshaft continues to rotate repeatedly in the normal and reverse directions is equal to or longer than a predetermined period, the condition is deemed to be satisfied and the drive process is executed. 3. The vehicle control device according to claim 1, wherein in the drive processing, when the oil pressure in the chain tensioner is low, a target value for the pressure of the oil discharged from the oil pump is set to be higher than when the oil pressure in the chain tensioner is high. When the rotation direction of the crankshaft when the chain runs on the driving sprocket, the oscillating guide, and the driven sprocket in this order is defined as a first rotation direction, and the direction opposite to the first rotation direction is defined as a second rotation direction,
4. The vehicle control device according to claim 1, further comprising: a pressure of oil in the chain tensioner being estimated based on an integrated value of an amount of rotation of the crankshaft in the second rotational direction during the EV mode. The vehicle control device according to any one of claims 1 to 4, wherein in the drive process, the crankshaft is rotated by causing the internal combustion engine to operate autonomously. In the driving process,
When the charging rate of the battery is less than a predetermined specified value, the internal combustion engine is operated autonomously to rotate the crankshaft;
The vehicle control device according to any one of claims 1 to 5, further comprising: a drive force of the motor generator being transmitted to the crankshaft to rotate the crankshaft when the charging rate of the battery is equal to or higher than the specified value.