Vehicle control device

Abstract

To provide a vehicle control device capable of performing evacuation travel even when a connection failure occurs.SOLUTION: An electronic control device 70 comprises: a connection failure detection section 72 which performs control in a manner that detects a connection failure in a first drive mechanism 16 or a second drive mechanism 18 when determining that an absolute value of a difference between a first rotation speed Ndv1 calculated based on an engine rotation speed Ne and an MG1 rotation speed Nm1 and a second rotation speed Ndv2 calculated based on an MG2 rotation speed Nm2 and a deceleration ratio γ is larger than a predetermined value Na; and an evacuation travel control section 74 which performs control in a manner that determines whether a vehicle 10 is accelerated by an increase in the rotation speed of an electric motor MG2 after transiting to travel only with power of the electric motor MG2 when the connection failure is detected, determines that the first drive mechanism 16 has the connection failure when the determination is affirmative, and continues the travel only with the power of the second electric motor, and determines that the second drive mechanism 18 has the connection failure when the determination is negative and transits to the travel only with the power of an engine 12.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a control device for a hybrid vehicle, and to a technique for performing evacuation running when a connection failure occurs in the drive train. [Background technology]

[0002] In a hybrid vehicle equipped with an engine and an electric motor as a power source for running, when the engine breaks down and the vehicle cannot run on engine power, a technique has been disclosed for operating only the electric motor to run an evacuation route. For example, Patent Document 1 describes a control method for a hybrid vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-182619 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, a vehicle may become unable to run due to a malfunction of the power source such as the engine or electric motor, or due to a connection failure in the power transmission path, such as a malfunction of the torque limiter provided in the damper directly connected to the engine, or deterioration or damage to gears or other components disposed at key points in the power transmission path, which can cause power transmission to be interrupted.

[0005] In response to the above-mentioned poor connection, in a vehicle equipped with an engine, a first electric motor, a first drive mechanism including a planetary gear device that divides and transmits the power from the engine to the first electric motor and an output shaft, a second drive mechanism including a second electric motor and a reduction gear device that reduces the power of the second electric motor and transmits it to the output shaft, and the output shaft that transmits power to the drive wheels, control is performed to transition to evacuation driving using only the power of the second electric motor, assuming a poor connection due to a failure of the torque limiter provided in the damper mentioned above, if the difference between the first rotational speed of the output shaft calculated based on the rotational speed of the engine and the first electric motor and the second rotational speed of the output shaft calculated based on the rotational speed of the second electric motor and the reduction ratio of the reduction gear device is greater than a predetermined value.

[0006] However, the above-mentioned control only assumes failure of the torque limiter, and as a result, evacuation driving can only be performed to the extent of a poor connection occurring in the first drive mechanism, so there was a problem that if a poor connection occurred in the second drive mechanism, driving would become impossible.

[0007] The present invention has been made against the background of the above circumstances, and its purpose is to provide a vehicle control device that enables evacuation driving even if a poor connection occurs in either the first drive mechanism or the second drive mechanism in the vehicle. [Means for solving the problem]

[0008] The gist of the present invention is a control device for a vehicle including: (a) a first drive mechanism including an engine, a first electric motor, and a planetary gear device that divides and transmits power from the engine to the first electric motor and an output shaft; a second drive mechanism including a second electric motor and a reduction gear device that reduces the power of the second electric motor and transmits it to the output shaft; and the output shaft that transmits power to drive wheels, wherein (b) an absolute value of a difference between a first rotation speed of the output shaft calculated based on the rotation speeds of the engine and the first electric motor and a second rotation speed of the output shaft calculated based on the rotation speed of the second electric motor and the reduction ratio of the reduction gear device is and (c) an evacuation driving control unit that, when the poor connection detection unit detects a poor connection, performs control to detect a poor connection of the first drive mechanism or the second drive mechanism by determining that the value is greater than the predetermined value, and determines whether the vehicle has accelerated due to an increase in the rotation speed of the second electric motor after transitioning to running using only the power of the second electric motor, and if the determination is positive, isolates it to a poor connection of the first drive mechanism and continues running using only the power of the second electric motor, and if the determination is negative, isolates it to a poor connection of the second drive mechanism and controls to transition to running using only the power of the engine. [Effects of the Invention]

[0009] According to the present invention, the control device includes a poor coupling detection unit that performs control to detect poor coupling of the first drive mechanism or the second drive mechanism by determining that an absolute value of a difference between a first rotation speed of the output shaft calculated based on the rotation speeds of the engine and the first electric motor and a second rotation speed of the output shaft calculated based on the rotation speed of the second electric motor and the reduction ratio of the reduction gear is greater than a predetermined value, and an emergency run control unit that, when the poor coupling detection unit detects a poor coupling, determines whether the vehicle has accelerated due to an increase in the rotation speed of the second electric motor after transitioning to running only using power of the second electric motor, and if the determination is positive, determines that the poor coupling is of the first drive mechanism and continues running only using power of the second electric motor, or if the determination is negative, determines that the poor coupling is of the second drive mechanism and performs control to transition to running only using power of the engine. This makes it possible to perform emergency run even if a poor coupling occurs in either the first drive mechanism or the second drive mechanism. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating a schematic configuration of a vehicle to which the present invention is applied, and is also a diagram illustrating main parts of control functions and control systems for various controls in the vehicle. [Figure 2] FIG. 10 is a diagram illustrating the rotation speed of the output shaft used to detect poor connection. [Figure 3] 3 is a flowchart illustrating a main part of the control operation of the electronic control device. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Example]

[0012] Fig. 1 is a diagram illustrating the schematic configuration of a vehicle 10 to which the present invention is applied, and also illustrates the main parts of a control system for various controls in the vehicle 10. In Fig. 1, the vehicle 10 is a hybrid vehicle equipped with a first drive mechanism 16 powered by an engine 12, a second drive mechanism 18 powered by a second electric motor (hereinafter referred to as electric motor MG2), drive wheels 14, and a power transmission device 20 that connects the first drive mechanism 16 and the second drive mechanism 18 to the drive wheels 14 so that power can be transmitted between them.

[0013] The first drive mechanism 16 includes an engine 12, a damper 22, an input shaft 24, a transmission unit 26, and the like.

[0014] The engine 12 is a known internal combustion engine, and the engine torque Te of the engine 12 is controlled by an engine control device 50 .

[0015] The damper 22 is a device that absorbs torque fluctuations of the engine 12. The damper 22 also includes a torque limiter that prevents torque transmission that exceeds a predetermined limit torque Tlim, i.e., that limits the transmission of torque greater than the limit torque Tlim.

[0016] The transmission unit 26 includes a first electric motor (hereinafter referred to as electric motor MG1) and a planetary gear set 40. The electric motor MG1 is a rotating electric machine connected to a battery 54 that receives and supplies electric power via an inverter 52, and the MG1 torque Tm1 of the electric motor MG1 is controlled by the inverter 52. The planetary gear set 40 is a known single-pinion planetary gear set that includes a sun gear S, a carrier CA, a ring gear R, and a plurality of pinions P that are supported by the carrier CA so as to be able to rotate and revolve. The carrier CA is connected to the engine 12 via the input shaft 24 so as to be able to transmit power, and the sun gear S is connected to the electric motor MG1 so as to be able to transmit power. The ring gear R is connected to the output shaft 28 so as to be able to transmit power. The planetary gear set 40 is a power split mechanism that mechanically splits and transmits the power of the engine 12, which is input to the carrier CA, to the sun gear S (electric motor MG1) and the ring gear R (output shaft 28).

[0017] In the transmission unit 26, MG1 torque Tm1, which is a reaction torque of the negative torque generated by the electric motor MG1 in response to the engine torque Te, which is a positive torque, input to the carrier CA, is input to the sun gear S. As a result, a positive direct engine torque Td (= Te / (1+ρ) = -(1 / ρ) × Tm1) appears in the ring gear R during forward rotation. The above "ρ" is the gear ratio of the planetary gear set 40 (= number of teeth of the sun gear / number of teeth of the ring gear). The transmission unit 26 is a known electric continuously variable transmission in which the differential state of the planetary gear set 40 is controlled by controlling the operating state of the electric motor MG1 in relation to the engine torque Te.

[0018] The second drive mechanism 18 includes an electric motor MG2, a reduction gear 36, and the like.

[0019] The electric motor MG2 is a rotating electric machine, and is connected to a battery 54 that receives and supplies electric power via an inverter 56. The inverter 56 controls the MG2 torque Tm2 of the electric motor MG2.

[0020] The reduction gear 36 is a device that reduces the rotational speed of the electric motor MG2 (MG2 rotational speed Nm2) and increases the transmission torque. The output gear of the reduction gear 36 meshes with the driven gear 30 disposed on the output shaft 28, and the MG2 rotational speed Nm2 is transmitted to the output shaft 28 at a reduction ratio γ. The reduction ratio γ is set in advance or experimentally. The reduction gear 36 is, for example, composed of a plurality of gears, and the reduction ratio γ can be switched between two levels, high and low, by switching the combination of the gears using hydraulic control or the like. The switching of the reduction ratio γ is controlled by an electronic control device 70 (described later) according to the driving conditions. The reduction gear 36 may also be a reduction gear with a fixed reduction ratio γ.

[0021] The power transmission device 20 includes an output shaft 28, a driven gear 30, a final gear 32, a differential gear 34 (hereinafter referred to as the diff 34), and a pair of drive shafts 38 connected to the diff 34. The final gear 32 is in mesh with a diff ring gear 34a of the diff 34.

[0022] The power transmission device 20 transmits the power output through the transmission section 26 of the engine 12, which is transmitted to the output shaft 28, and the power output from the reduction gear 36 of the electric motor MG2 through the driven gear 30 from the output shaft 28 to the drive wheels 14 sequentially via the final gear 32, differential 34, drive shaft 38, etc.

[0023] The vehicle 10 is equipped with an electronic control device 70, which is configured to include a microcomputer. The electronic control device 70 is supplied with various signals (e.g., engine rotation speed Ne, accelerator pedal position pap, MG1 rotation speed Nm1, MG2 rotation speed Nm2, wheel speed Nw, longitudinal acceleration Gx and lateral acceleration Gy of the vehicle 10, etc.) based on detection values ​​from various sensors (e.g., engine rotation speed sensor 80, accelerator pedal position sensor 82, MG1 rotation speed sensor 86, MG2 rotation speed sensor 88, wheel speed sensor 90, G sensor 92, etc.) provided on the vehicle 10. The electronic control device 70 outputs various command signals (e.g., engine control command signal Se, MG1 control command signal Sm1, MG2 control command signal Sm2, MG2 reduction ratio command signal Sγ, etc.) to various devices (e.g., engine control device 50, inverter 52, inverter 56, reduction gear 36, etc.) provided on the vehicle 10.

[0024] The electronic control device 70 functionally comprises a poor connection detection unit 72 that performs control to detect poor connections, and an evacuation driving control unit 74 that isolates the defective parts of the poor connections detected by the poor connection detection unit 72 and controls transition to evacuation driving.

[0025] The poor connection detection unit 72 detects poor connection by determining the difference between the first rotational speed Ndv1 of the output shaft 28 calculated based on the engine rotational speed Ne and the MG1 rotational speed Nm1 (rotational speed information of the first drive mechanism) and the second rotational speed Ndv2 of the output shaft 28 calculated based on the MG2 rotational speed Nm2 and the reduction ratio γ (rotational speed information of the second drive mechanism).

[0026] 2 is a diagram illustrating the relationship and calculation method of the first rotation speed Ndv1 and the second rotation speed Ndv2. The first rotation speed Ndv1 is equivalent to the rotation speed of the ring gear R of the planetary gear device 40, and is calculated from the MG1 rotation speed Nm1 of the electric motor MG1 connected to the sun gear S and the engine rotation speed Ne of the engine 12 connected to the carrier CA using the following equation (1). First rotation speed Ndv1=Ne+σ×(Ne-Nm1) (1) Moreover, since the electric motor MG2 is connected to the output shaft 28 via the reduction gear device 36, the second rotation speed Ndv2 is calculated by the following equation (2). Second rotational speed Ndv2=-γ×Nm2 (2) Normally, when no poor coupling occurs, the first rotation speed Ndv1 and the second rotation speed Ndv2 are equal in value, but when a poor coupling occurs, a discrepancy occurs between the calculated values. The poor coupling detection unit 72 detects a poor coupling of the first drive mechanism 16 or the second drive mechanism 18 by determining that the absolute value of the difference between the first rotation speed Ndv1 and the second rotation speed Ndv2 is greater than a predetermined value Na. The predetermined value Na is a value that is set in advance by design or experiment.

[0027] In the conventional example, the above-mentioned detection of poor connection was performed assuming a failure of the torque limiter provided in the damper 22, but when this was detected, control was implemented to unconditionally switch to running using only the power of the electric motor MG2, which posed a problem in that, for example, if a poor connection occurred in the second drive mechanism 18, the vehicle would be unable to run.

[0028] 3 is a flowchart illustrating the main control operations when a poor coupling is detected, which are performed by the poor coupling detection unit 72 and the evacuation travel control unit 74, which are functionally provided in the electronic control unit 70. The control operations will be explained below in accordance with the processing steps of FIG.

[0029] First, in step S10 (hereinafter, step will be omitted) corresponding to the poor connection detection unit 72, the first rotation speed Ndv1 and the second rotation speed Ndv2 are calculated, and then in S20, it is determined whether the absolute value of the difference between the first rotation speed Ndv1 and the second rotation speed Ndv2 is greater than a predetermined value Na.

[0030] If the determination in S20 is negative, this routine is terminated. If the determination in S20 is positive, control from S30 to S80 corresponding to the evacuation travel control unit 74 is performed. First, in S30, the vehicle 10 waits for stability by stopping (power cutting) the power sources such as the engine 12 and the electric motor MG2, and then in S40, the vehicle 10 is transitioned to traveling using only the electric motor MG2 as a power source. Next, in S50, it is determined whether an acceleration operation has been performed based on the accelerator opening pap from the accelerator opening sensor 82. If the determination in S50 is negative, the determination in S50 is repeated. If the determination in S50 is positive, the process transitions to S60, where it is determined whether the vehicle 10 has accelerated in response to the accelerator acceleration operation. The acceleration determination of the vehicle 10 is suitably performed using a preset method based on the amount of change in the wheel speed Nw from the wheel speed sensor 90, the longitudinal acceleration Gx of the vehicle 10 from the G sensor 92, etc. If the determination in S60 is positive, then in S70, the vehicle 10 accelerates due to an increase in the MG2 rotation speed Nm2 caused by accelerator acceleration operation, so the second drive mechanism 18 is normal and the problem is isolated to a poor connection of the other, first drive mechanism 16. Then, travel using only the electric motor MG2 as a power source continues, and this routine is terminated. If the determination in S60 is negative, then in S80, the vehicle 10 does not accelerate due to an increase in the MG2 rotation speed Nm2 caused by accelerator acceleration operation, so the problem is isolated to a poor connection of the second drive mechanism 18, and travel is transitioned to travel using only the engine 12 as a power source, and this routine is terminated.

[0031] As described above, the electronic control device 70 of this embodiment includes the following: a poor connection detection unit 72 that performs control to detect poor connection of the first drive mechanism 16 or the second drive mechanism 18 by determining that the absolute value of the difference between the first rotational speed Ndv1 of the output shaft 28, calculated based on the engine rotational speed Ne and the MG1 rotational speed Nm1, and the second rotational speed Ndv2 of the output shaft 28, calculated based on the MG2 rotational speed Nm2 and the reduction ratio γ of the reduction gear 36, is greater than a predetermined value Na; and an escape travel control unit 74 that, when the poor connection detection unit 72 detects a poor connection, determines whether the vehicle 10 has accelerated due to an increase in the rotational speed of the electric motor MG2 after transitioning to running using only the power of the electric motor MG2, and if the determination is positive, determines that the problem is a poor connection of the first drive mechanism 16 and continues running using only the power of the electric motor MG2; and, if the determination is negative, determines that the problem is a poor connection of the second drive mechanism 18 and performs control to transition to running using only the power of the engine 12. As a result, even if a connection failure occurs in either the first drive mechanism 16 or the second drive mechanism 18, evacuation travel is possible.

[0032] The above describes in detail an embodiment of the present invention based on the drawings, but what has been described above is merely one embodiment, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0033] 10: Vehicle 12: Engine 14: Drive wheels 16: First drive mechanism 18: Second drive mechanism 28: Output shaft 36: Reduction gear 40: Planetary gear device 70: Electronic control device (control device) 72: Connection failure detection unit 74: Evacuation travel control unit MG1: Electric motor (first electric motor) MG2: Electric motor (second electric motor) Na: Predetermined value Ndv1: First rotation speed Ndv2: Second rotation speed Ne: Engine rotation speed Nm1: MG1 rotation speed (rotation speed of first electric motor) Nm2: MG2 rotation speed (rotation speed of second electric motor)

Claims

[Claim 1] a first drive mechanism including an engine, a first electric motor, and a planetary gear device that divides and transmits power from the engine to the first electric motor and an output shaft; a second drive mechanism including a second electric motor and a reduction gear device that reduces the power of the second electric motor and transmits the reduced power to the output shaft; a control device for a vehicle including the output shaft that transmits power to drive wheels, a poor connection detection unit that performs control to detect poor connection of the first drive mechanism or the second drive mechanism by determining that an absolute value of a difference between a first rotation speed of the output shaft calculated based on the rotation speeds of the engine and the first electric motor and a second rotation speed of the output shaft calculated based on the rotation speed of the second electric motor and the reduction ratio of the reduction gear device is greater than a predetermined value; an emergency travel control unit that, when the connection failure detection unit detects a connection failure, determines whether the vehicle has accelerated due to an increase in the rotation speed of the second electric motor after transitioning to travel using only the power of the second electric motor, and, when the determination is affirmative, distinguishes the problem as a connection failure of the first drive mechanism and continues travel using only the power of the second electric motor, and, when the determination is negative, distinguishes the problem as a connection failure of the second drive mechanism and performs control to transition to travel using only the power of the engine. A vehicle control device characterized by:

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