Control system for hybrid vehicles

Abstract

To provide a controller of a hybrid vehicle which suppresses delay of timing to close a valve of an EGR device due to a sudden decrease in an intake air amount.SOLUTION: When an EGR rate is equal to or greater than a regulation ratio and when a battery can be charged, a controller according to the present invention uses part of output from an internal combustion engine to allow for charging the battery while keeping output demanded to the internal combustion engine. When the EGR rate is equal to or greater than the regulation ratio and when the battery cannot be charged, the controller changes a reduction degree of the output demanded to the internal combustion engine to be smaller than the reduction degree before the change. In a state where the reduction degree of the output demanded to the internal combustion engine is changed, the controller performs close control of an EGR valve on condition that an intake air amount GA is less than a predetermined amount.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a control device for a hybrid vehicle.

Background Art

[0002] Patent Document 1 describes a hybrid vehicle including an internal combustion engine and a motor generator as drive sources. The internal combustion engine has an EGR device that recirculates the exhaust discharged from the cylinder into the intake passage as EGR gas. The control device for the hybrid vehicle performs a valve closing control of the EGR device when the degree of decrease in the output required for the internal combustion engine is greater than a predetermined degree of decrease.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a hybrid vehicle as described in Patent Document 1, when the intake air amount suddenly decreases, there is a possibility that the timing for closing the valve of the EGR device may be delayed.

Means for Solving the Problems

[0005] To solve the above problems, the present invention is applied to a hybrid vehicle comprising: an internal combustion engine, which is a drive source, having an EGR device that recirculates exhaust gas discharged from the cylinder into the exhaust passage as EGR gas into the intake passage; a motor generator, which is a drive source; and a battery that is charged by the motor generator using the output of the internal combustion engine, and is a control device that performs valve closing control to close a valve that allows the recirculation of the EGR gas in the EGR device, provided that the amount of intake air drawn into the combustion chamber of the internal combustion engine is less than a predetermined amount, and during deceleration of the hybrid vehicle while the internal combustion engine is running, the fluid flowing into the combustion chamber via the EGR device is a portion of the fluid flowing into the combustion chamber This is a control device for a hybrid vehicle that, when the EGR rate, which is the proportion of the EGR gas that has been discharged, is equal to or greater than a specified ratio and the battery can be charged, charges the battery by the motor generator using a portion of the output of the internal combustion engine while maintaining the output required of the internal combustion engine. When the hybrid vehicle is decelerating while the internal combustion engine is running, and the EGR rate is equal to or greater than the specified ratio and the battery cannot be charged, the degree of reduction in the output required of the internal combustion engine is changed to be less than the degree of reduction before the change, and with the degree of reduction in the output required of the internal combustion engine changed, determines whether the amount of intake air is less than a predetermined amount. [Effects of the Invention]

[0006] With the above configuration, by reducing the degree of decrease in the output required from the internal combustion engine, a rapid decrease in the intake air volume can be suppressed. Therefore, by determining whether the intake air volume is below a predetermined amount while suppressing a rapid decrease in the intake air volume, a delay in closing the EGR device valve can be suppressed. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram illustrating a hybrid vehicle. [Figure 2] Figure 2 is a flowchart showing a series of processes including EGR valve closing control. [Modes for carrying out the invention]

[0008] The following describes one embodiment of a control device for a hybrid vehicle. The hybrid vehicle equipped with this control device will be described below with reference to the drawings. <Vehicle Overview> As shown in Figure 1, the hybrid vehicle 100 is equipped with a spark-ignition type internal combustion engine 10 as a drive source. The hybrid vehicle 100 is also equipped with a first motor generator 71 and a second motor generator 72 that combine the functions of both an electric motor and a generator.

[0009] The internal combustion engine 10 has an engine body 11. The engine body 11 comprises a plurality of cylinders 12 and a crankshaft 13. Each cylinder 12 is a space for burning a mixture of fuel and intake gas. The engine body 11 has four cylinders 12.

[0010] The crankshaft 13 is connected to pistons (not shown) located within each cylinder 12. The space partitioned by the inner wall of the cylinder 12 and the piston constitutes the combustion chamber R. When fuel burns in each combustion chamber R, the crankshaft 13, which is connected to the operating piston, rotates.

[0011] Furthermore, the internal combustion engine 10 has an intake passage 21, a throttle valve 22, a plurality of fuel injectors 23, and a plurality of ignition devices 24. The internal combustion engine 10 also has an exhaust passage 26, a catalyst 27, and a filter 28. The internal combustion engine 10 also has an EGR device 30.

[0012] The intake passage 21 is connected to the cylinder 12. A portion of the intake passage 21, including its downstream end, branches into four. Each of the branched passages is connected to each cylinder 12. The intake passage 21 is for supplying intake gas from outside the internal combustion engine 10 to the combustion chamber R.

[0013] The throttle valve 22 is located upstream of the branched portion of the intake passage 21. The throttle valve 22 adjusts the intake gas flow rate, which is the amount of intake gas flowing through the intake passage 21.

[0014] The fuel injectors 23 are located near the downstream end of the intake passage 21. The internal combustion engine 10 has four fuel injectors 23 corresponding to the four cylinders 12. The fuel injectors 23 inject liquid fuel supplied from the fuel tank into the intake passage 21. An ignition device 24 is located for each of the four cylinders 12. The ignition device 24 ignites the mixture of fuel and intake gas by spark discharge in order to burn it in the combustion chamber R.

[0015] The exhaust passage 26 is connected to the cylinder 12. A portion of the exhaust passage 26, including its upstream end, branches into four. Each branched passage is connected to each cylinder 12. The exhaust passage 26 discharges exhaust gas from each cylinder 12 to the outside of the internal combustion engine 10.

[0016] The catalyst 27 is located downstream of the branched portion of the exhaust passage 26. The catalyst 27 purifies the exhaust gas flowing through the exhaust passage 26. The filter 28 is located downstream of the catalyst 27 in the exhaust passage 26. The filter 28 collects particulate matter contained in the exhaust gas flowing through the exhaust passage 26.

[0017] The EGR device 30 has an EGR passage 31 and an EGR valve 32. The EGR device 30 recirculates a portion of the exhaust gas discharged from the cylinder 12 into the exhaust passage 26 as EGR (Exhaust Gas Recirculation) gas to the intake passage 21. The EGR passage 31 is the passage through which the exhaust gas is recirculated from the exhaust passage 26 to the intake passage 21. The EGR valve 32 is a valve for adjusting the recirculation rate of the EGR gas. When the EGR valve 32 is open, recirculation of the EGR gas is permitted. When the EGR valve 32 is closed, recirculation of the EGR gas is not permitted.

[0018] As shown in FIG. 1, the hybrid vehicle 100 includes a first planetary gear mechanism 40, a ring gear shaft 45, a second planetary gear mechanism 50, a speed reduction mechanism 62, a differential mechanism 63, and a plurality of drive wheels 64.

[0019] The first planetary gear mechanism 40 includes a sun gear 41, a ring gear 42, a plurality of pinion gears 43, and a carrier 44. The sun gear 41 is an external gear. The sun gear 41 is connected to the first motor generator 71. The ring gear 42 is an internal gear and is located coaxially with the sun gear 41. Each pinion gear 43 is located between the sun gear 41 and the ring gear 42. Each pinion gear 43 meshes with both the sun gear 41 and the ring gear 42. The carrier 44 supports the pinion gears 43. The pinion gears 43 are rotatable and revolvable by rotating together with the carrier 44. The carrier 44 is connected to the crankshaft 13.

[0020] The ring gear shaft 45 is connected to the ring gear 42. The ring gear shaft 45 is also connected to the drive wheels 64 via the speed reduction mechanism 62 and the differential mechanism 63. The speed reduction mechanism 62 reduces and outputs the rotational speed of the ring gear shaft 45. The differential mechanism 63 allows a difference in rotational speed to occur between the left and right drive wheels 64.

[0021] The second planetary gear mechanism 50 includes a sun gear 51, a ring gear 52, a plurality of pinion gears 53, a carrier 54, and a case 55. The sun gear 51 is an external gear. The sun gear 51 is connected to the second motor generator 72. The ring gear 52 is an internal gear and is located coaxially with the sun gear 51. The ring gear 52 is connected to the ring gear shaft 45. Each pinion gear 53 is located between the sun gear 51 and the ring gear 52. Each pinion gear 53 meshes with both the sun gear 51 and the ring gear 52. The carrier 54 supports the pinion gears 53. The pinion gears 53 are rotatable. The carrier 54 is fixed to the case 55. Therefore, the pinion gears 53 are in a non-revolvable state.

[0022] The hybrid vehicle 100 includes a battery 75, a first inverter 76, and a second inverter 77. The battery 75 is a secondary battery. The first inverter 76 performs AC-DC power conversion between the first motor generator 71 and the battery 75. Also, the first inverter 76 adjusts the amount of power transfer between the first motor generator 71 and the battery 75. The second inverter 77 performs AC-DC power conversion between the second motor generator 72 and the battery 75. The second inverter 77 adjusts the amount of power transfer between the second motor generator 72 and the battery 75. And the battery 75 is charged by the first motor generator 71 and the second motor generator 72 using the output of the internal combustion engine 10 when the first inverter 76 and the second inverter 77 are controlled.

[0023] The hybrid vehicle 100 includes a vehicle speed sensor 81, an accelerator sensor 82, an air flow meter 83, and a battery sensor 84. The vehicle speed sensor 81 detects the vehicle speed VS and outputs a signal corresponding to the vehicle speed VS as a detection signal. The accelerator sensor 82 detects the accelerator opening ACC as the operation amount of the accelerator pedal and outputs a signal corresponding to the accelerator opening ACC as a detection signal.

[0024] The air flow meter 83 detects the intake air amount GA which is the amount of intake air flowing through the intake passage 21 and outputs a signal corresponding to the intake air amount GA as a detection signal. The battery sensor 84 detects battery information VI such as the current, output voltage, and temperature of the battery 75.

[0025] The hybrid vehicle 100 is equipped with a control device 90. The control device 90 is applied to the hybrid vehicle 100, with the hybrid vehicle 100 as the control target. The control device 90 can be configured as one or more processors that execute various processes according to a computer program (software). The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or commands configured to cause the CPU to execute processes. Detection signals are input to the control device 90 from the various sensors mentioned above.

[0026] The control device 90 calculates the output required from the internal combustion engine 10 based on the accelerator pedal position (ACC) and vehicle speed (VS). The control device 90 also controls the internal combustion engine 10 to achieve the calculated output.

[0027] The control device 90 determines whether the hybrid vehicle 100 is decelerating while the internal combustion engine 10 is running. Specifically, the control device 90 determines that the hybrid vehicle 100 is decelerating when the acquired vehicle speed VS decreases while the internal combustion engine 10 is running.

[0028] The control device 90 determines whether the EGR rate is above a predetermined specified ratio during deceleration of the hybrid vehicle 100 while the internal combustion engine 10 is running. The EGR rate is the ratio of EGR gas that flows into the combustion chamber R via the EGR device 30 to the total fluid flowing into the combustion chamber R. In other words, the EGR rate is the value obtained by dividing the amount of EGR gas by the amount of intake air GA. The control device 90 repeatedly calculates the EGR rate based on the opening degree of the EGR valve 32 and the amount of intake air GA. The specified ratio is determined in advance through tests and simulations as the ratio at which the amount of EGR gas becomes excessively large, causing misfires in the internal combustion engine 10.

[0029] <Regarding the series of processes including valve closing control> When the hybrid vehicle 100 is decelerating with the internal combustion engine 10 running, the control device 90 starts a series of processes, including closing control of the EGR valve 32, when the EGR rate is above a specified ratio.

[0030] As shown in Figure 2, when the control device 90 starts a series of processes including the closing control of the EGR valve 32, it first performs the process in step S11. In step S11, the control device 90 determines whether or not the battery 75 can be charged based on the battery information VI detected from the battery sensor 84. If the battery 75 can be charged (S11: YES), the control device 90 proceeds to step S12.

[0031] In step S12, the control device 90 maintains the output required from the internal combustion engine 10 in response to deceleration, and uses a portion of the output of the internal combustion engine 10 to charge the battery 75. The control device 90 controls the first motor generator 71, the second motor generator 72, the first inverter 76, and the second inverter 77 to charge the battery 75. After that, the control device 90 proceeds to step S13.

[0032] By the way, if it is not possible to charge the battery 75 (S11: NO), the control device 90 proceeds to step S13. In step S13, the control device 90 changes the degree of reduction in the output required from the internal combustion engine 10 to a smaller degree than the reduction before the change. Specifically, the control device 90 calculates a larger output required from the internal combustion engine 10 so that the reduction is smaller than the predetermined degree of reduction in the output required from the internal combustion engine 10 according to the deceleration. If the control device 90 has already reduced the degree of reduction in the output required from the internal combustion engine 10 by repeating the series of processes in step S13, it maintains the changed state of the degree of reduction in the output required from the internal combustion engine 10 and finishes the process in step S13. After that, the control device 90 proceeds to step S14.

[0033] In step S14, the control device 90 determines whether the intake air volume GA is less than a predetermined amount. The predetermined amount is determined in advance through tests and simulations as the amount at which the intake air volume GA becomes excessively large and causes misfires in the internal combustion engine 10. When proceeding to step S14 after step S13, the control device 90 determines whether the intake air volume GA is less than the predetermined amount while changing the degree of reduction in the output required of the internal combustion engine 10. On the other hand, when proceeding to step S14 after step S12, if the output of the internal combustion engine 10 is maintained and the intake air volume GA is equal to or greater than the predetermined amount, the control device 90 makes a negative determination. If the intake air volume GA is equal to or greater than the predetermined amount (S14: NO), the control device 90 returns to step S11. On the other hand, if the intake air volume GA is less than the predetermined amount (S14: YES), the control device 90 proceeds to step S15.

[0034] In step S15, the control device 90 closes the EGR valve 32. In other words, since the process in step S15 is performed after a positive determination in step S14, the control device 90 controls the closing of the EGR valve 32 on the condition that the intake air volume GA is less than a predetermined amount. After that, the control device 90 terminates the series of processes.

[0035] Furthermore, even if the control device 90 is in the middle of a series of processes, when the hybrid vehicle 100 is no longer decelerating, or when the EGR rate exceeds a predetermined ratio, it returns the degree of reduction in the output required by the internal combustion engine 10 from a reduced state to the original state. After that, the control device 90 terminates the series of processes.

[0036] <Effects and Effects of the Embodiment> (1) According to the above embodiment, when the hybrid vehicle 100 is decelerating and the EGR rate is above a specified ratio and the battery 75 is not able to be charged, the control device 90 reduces the degree of reduction in the output required from the internal combustion engine 10. This suppresses a rapid decrease in the intake air volume GA when the EGR rate is above a specified ratio. Therefore, the control device 90 can determine whether the intake air volume GA is below a predetermined amount while suppressing a rapid decrease in the intake air volume GA. This suppresses a delay in the timing of closing the EGR valve 32 due to a delay in the timing of determining that the intake air volume GA is below a predetermined amount.

[0037] (2) According to the above embodiment, when the battery 75 is ready for charging, the control device 90 maintains the output to the internal combustion engine 10 and uses a portion of the output of the internal combustion engine 10 to charge the battery 75. In this case, the hybrid vehicle 100 can maintain its deceleration by using a portion of the output of the internal combustion engine 10 to charge the battery 75. Therefore, while the battery 75 is ready for charging during deceleration, a decrease in the intake air volume GA can be suppressed. [Explanation of Symbols]

[0038] 10...Internal combustion engine, 12...Cylinder, 21...Intake passage, 26...Exhaust passage, 30...EGR device, 75...Battery, 90...Control device, 100...Hybrid vehicle

Claims

[Claim 1] A control device is applied to a hybrid vehicle comprising an internal combustion engine, which is a drive source, having an EGR device that recirculates exhaust gas discharged from the cylinder into the exhaust passage as EGR gas into the intake passage; a motor generator, which is a drive source; and a battery that is charged by the motor generator using the output of the internal combustion engine, and which performs valve closing control to close a valve that allows the recirculation of the EGR gas in the EGR device, provided that the amount of intake air drawn into the combustion chamber of the internal combustion engine is less than a predetermined amount, During deceleration of the hybrid vehicle while the internal combustion engine is running, if the EGR rate, which is the ratio of the EGR gas flowing into the combustion chamber via the EGR device to the fluid flowing into the combustion chamber, is equal to or greater than a specified ratio, and the battery can be charged, the motor generator will charge the battery using a portion of the output of the internal combustion engine while maintaining the output required of the internal combustion engine. When the hybrid vehicle is decelerating with the internal combustion engine running, if the EGR rate is equal to or greater than the specified ratio and the battery cannot be charged, the degree of reduction in the output required by the internal combustion engine is changed to be less than the degree of reduction before the change, and with the degree of reduction in the output required by the internal combustion engine changed, it is determined whether or not the intake air volume is less than the predetermined amount. Control system for hybrid vehicles.

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