Hybrid vehicles

Abstract

This suppresses increased vehicle vibration that occurs when the friction engagement elements of a stepped transmission slip. [Solution] The hybrid vehicle comprises an engine, a stepped transmission having multiple friction engagement elements and connected to the engine, a motor provided between the stepped transmission and a drive shaft connected to the drive wheels, and a control device. The control device estimates the front inertia on the engine side of the drive shaft based on the slip ratio of the friction engagement elements of the stepped transmission, estimates the torsional primary resonance frequency of the drive shaft based on the front inertia, and performs vibration damping control by the motor to reduce the component of the torsional primary resonance frequency.

Description

Technical Field

[0001] The present disclosure relates to a hybrid vehicle.

Background Art

[0002] Conventionally, a hybrid vehicle has been proposed that includes an engine and a motor, and a drive system that transmits torque output from the engine and the motor to drive wheels (see Patent Document 1). Here, the drive system includes a torque converter in which the engine and the motor are connected to an input shaft and includes a lock-up damper, a transmission (a stepped transmission) connected to the output shaft of the torque converter, and a drive shaft connected to the transmission. In this hybrid vehicle, when simulating the engine, the motor, and the drive system with a multi-degree-of-freedom vibration model, the inverse of the transfer function of a single-degree-of-freedom vibration model equivalent to the multi-degree-of-freedom vibration model in one of the plurality of natural vibration modes of the multi-degree-of-freedom vibration model is used to calculate the vibration damping torque that the motor should output to suppress the vibration of the drive system from the estimated value of the torque output from the engine, and the motor is controlled to output the vibration damping torque.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described hybrid vehicle, when a friction engagement element slips, such as during a change in the gear stage of a stepped transmission, the torsional primary resonance frequency of the drive shaft may change due to the influence, and the vibration of the vehicle may increase to a certain extent.

[0005] The primary purpose of the hybrid vehicle disclosed herein is to suppress increased vehicle vibration when the friction engagement element of the stepped transmission slips. [Means for solving the problem]

[0006] The hybrid vehicle of this disclosure employs the following means to achieve the primary objective described above.

[0007] The hybrid vehicle disclosed herein is A hybrid vehicle comprising an engine, a stepped transmission having multiple friction engagement elements and connected to the engine, a motor provided between the stepped transmission and a drive shaft connected to the drive wheels, and a control device, The control device is Based on the slip ratio of the friction engagement element of the stepped transmission, the front inertia on the engine side of the drive shaft is estimated. Based on the aforementioned front inertia, the torsional primary resonance frequency of the drive shaft is estimated. The motor performs vibration damping control to reduce the component of the torsional primary resonant frequency. This is the gist of it.

[0008] In the hybrid vehicle of this disclosure, the control device estimates the front inertia on the engine side of the drive shaft based on the slip ratio of the friction engagement element of the stepped transmission, estimates the torsional primary resonance frequency of the drive shaft based on the front inertia, and performs vibration damping control by the motor to reduce the component of the torsional primary resonance frequency. This makes it possible to more appropriately estimate the torsional primary resonance frequency of the drive shaft when the friction engagement element is slipping, thereby suppressing an increase in vehicle vibration.

[0009] In the hybrid vehicle of this disclosure, the control device may control the motor using a filtered torque command obtained by applying a bandstop filter to the torque command of the motor to reduce the component of the torsional primary resonance frequency.

[0010] In the hybrid vehicle of this disclosure, the motor may be connected to the stepped transmission and the differential gear connected to the drive shaft. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of the hybrid vehicle according to the embodiment of the present disclosure. [Figure 2] This is a flowchart showing an example of a processing routine. [Figure 3] This is an explanatory diagram showing an example of a torsional primary resonant frequency map. [Modes for carrying out the invention]

[0012] Embodiments for implementing this disclosure will be described with reference to the drawings. Figure 1 is a schematic diagram of a hybrid vehicle 20 according to an embodiment of this disclosure. As shown in the figure, the hybrid vehicle 20 of the embodiment comprises an engine 22, a power transmission device 30, a motor 40, an inverter 42, a battery 44, and an electronic control unit (hereinafter referred to as "ECU") 50.

[0013] The engine 22 is configured as an internal combustion engine that outputs power using fuel such as gasoline or diesel. The crankshaft 23 of the engine 22 is connected to the power transmission device 30.

[0014] The power transmission system 30 comprises a torque converter 31 and an automatic transmission 32. The torque converter 31 is configured as a general fluid transmission system and includes a pump impeller, a turbine runner, a stator, and a lock-up clutch. The pump impeller is connected to the crankshaft 23. The turbine runner is positioned opposite the pump impeller and is connected to the input shaft 33 of the automatic transmission 32. The stator is positioned between the pump impeller and the turbine runner. The lock-up clutch connects and disconnects the pump impeller and the turbine runner. The torque converter 31 transmits power from the engine 22 to the input shaft 33 of the automatic transmission 32 with amplified torque, or transmits it without torque amplification, by engaging and disengaging the lock-up clutch.

[0015] The automatic transmission 32 is configured as a stepped transmission and includes an input shaft 33, an output shaft 34, a plurality of planetary gear mechanisms, and a plurality of hydraulically driven friction engagement elements (clutches, brakes). The input shaft 33 is connected to the turbine runner of the torque converter 31. The output shaft 34 is connected to the rotor shaft of the motor 40. Each of the plurality of friction engagement elements has a hydraulic servo consisting of a piston, a plurality of friction engagement plates (friction plates and separator plates), an oil chamber to which hydraulic fluid is supplied, etc. The automatic transmission 45 forms a plurality of forward and reverse stages by engaging and disengaging the plurality of friction engagement elements and transmits them between the input shaft 33 and the output shaft 34. The power transmission device 30 is supplied with hydraulic fluid from a mechanical oil pump or an electric oil pump, with the hydraulic pressure regulated by a hydraulic control device (not shown). The hydraulic control device includes a valve body with a plurality of oil passages, a plurality of regulator valves, a plurality of linear solenoid valves, etc.

[0016] The motor 40 is configured as a synchronous generator-motor and comprises a rotor with permanent magnets embedded in its rotor core and a stator with three-phase (U-phase, V-phase, W-phase) coils wound around its stator core. The rotor shaft to which the rotor is attached is connected to a drive shaft 46 which is connected to the drive wheel DW via a drive shaft DW and a differential gear DF, and is also connected to the output shaft 34 of the automatic transmission 32. The inverter 42 has multiple switching elements. The motor 40 (rotor) is rotationally driven by the switching of the multiple switching elements of the inverter 42. The battery 44 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery and is connected to the inverter 42 via a power line.

[0017] The ECU50 is equipped with a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports, as well as various drive circuits and various logic ICs. Signals from various sensors are input to the ECU50. For example, the ECU50 receives the crank angle θcr of the crankshaft 23 of the engine 22 from the rotation speed sensor 23a, the rotation speed Ni of the input shaft 33 of the automatic transmission 32 from the rotation speed sensor 33a, the rotation speed No of the output shaft 34 of the automatic transmission 32 from the rotation speed sensor 34a, and the rotation position θm of the rotor of the motor 40 from the rotation position sensor 40a. The ECU50 also receives the voltage Vb and current Ib of the battery 44 from voltage sensors and current sensors. The ECU 50 also receives the following inputs: an on / off signal from the power switch 60, the shift position SP which is the operating position of the shift lever 61 from the shift position sensor 62, the accelerator opening Acc which is the amount the accelerator pedal 63 is pressed from the accelerator pedal position sensor 64, the brake pedal position BP which is the amount the brake pedal 65 is pressed from the brake pedal position sensor 66, and the vehicle speed V from the vehicle speed sensor 67.

[0018] Various control signals are output from the ECU 50. For example, control signals from the ECU 50 include a control signal to the engine 22, a control signal to the lock-up clutch of the power transmission device 30 and the automatic transmission 32 (hydraulic control device), and a control signal to the inverter 42. The ECU 50 calculates the electrical angle θe and the rotational speed Nm of the motor 40 based on the rotational position θm of the rotor of the motor 40, performs coordinate transformation (three-phase to two-phase transformation) of the phase currents Iu, Iv, Iw of each phase into the d-axis and q-axis currents Id, Iq using the electrical angle θe, and estimates the torque Tm of the motor 40 based on the d-axis and q-axis currents Id, Iq. The ECU 50 calculates the state of charge SOC of the battery 44 based on the integrated value of the current Ib of the battery 44.

[0019] In the hybrid vehicle 20 of the embodiment thus configured, the ECU 50 sets the required torque Td* for driving based on the accelerator opening Acc and the vehicle speed V, and sets the target torque Te* of the engine 22, the target gear position Gs* of the automatic transmission 32, and the torque command Tm* of the motor 40 so as to travel according to the required torque Td*. Subsequently, for the engine 22, operation control (such as intake air amount control, fuel injection control, ignition control, etc.) is executed so as to be operated based on the target torque Te*. Also, for the automatic transmission 32, control is performed so that the gear position Gs becomes the target gear position Gs*. Furthermore, for the motor 40, the inverter 24 is controlled so as to be driven based on a corrected torque command Tmco described later based on the torque command Tm*. Note that the hybrid vehicle 20 can travel not only with the operation of the engine 22 but also with the engine 22 stopped.

[0020] Here, the change of the gear stage Gs of the automatic transmission 32 of the power transmission device 30 is performed as follows. Among the plurality of friction engagement elements, for the release-side element that is switched from the engaged state to the released state, the hydraulic pressure is gradually decreased, and for the engagement-side element that is switched from the released state to the engaged state, fast fill is performed to fill the gap between the piston and the friction engagement plate, and then the hydraulic pressure is held at a relatively low standby pressure, and the hydraulic pressure of the engagement-side element is gradually increased. Along with this, the rotational speed Ni of the input shaft 43 changes toward the rotational speed after shifting corresponding to the target gear stage (inertia phase). Then, when the rotational speed Ni of the input shaft 43 reaches near the target rotational speed which is the rotational speed after the change of the gear stage Gs, the hydraulic pressure of the release-side element is gradually decreased and the hydraulic pressure of the engagement-side element is gradually increased, and the torque transmission is changed from the release-side element to the engagement-side element (torque phase), and the change of the gear stage Gs is completed. For this reason, during the change of the gear stage Gs, the release-side element and the engagement-side element are in a slip state.

[0021] Next, the operation of the hybrid vehicle 20 of the embodiment, particularly the vibration damping control by the motor 40, will be described. FIG. 2 is a flowchart showing an example of a processing routine executed by the ECU 50. This routine is repeatedly executed.

[0022] When this routine is executed, the ECU 50 first estimates the front inertia J1 which is the total inertia on the engine 22 side (from the engine 22 to the differential gear DF) rather than the drive shaft DS (step S100). In the embodiment, a model is considered in which the front inertia J1 and the rear inertia J2 which is the inertia on the drive wheel DW side rather than the drive shaft DS are connected via the drive shaft DS. The front inertia J1 is calculated by the formula (1) using the constant Jc, the correction coefficient α, the gear ratio Gr and the slip ratio Rs of the automatic transmission 32, and the inertia Jeat from the engine 22 to the automatic transmission 32.

[0023] J1 = Jc + α · (Gr 2 · Rs · Jeat) (1)

[0024] The constant Jc, the correction coefficient α, and the inertia Jeat from the engine 22 to the automatic transmission 32 are predetermined by experiments and analyses. The gear ratio Gr of the automatic transmission 32 is set to the gear ratio Gr corresponding to the current gear position Gs when the automatic transmission 32 is not changing gear position Gs, and to the gear ratio Gr corresponding to the gear position Gs before the change when the automatic transmission 32 is changing gear position Gs.

[0025] The slip ratio Rs of the automatic transmission 32 is the slip ratio between the input shaft 33 and the output shaft 34 (the total slip ratio of the release-side element and the engagement-side element as described above). The slip ratio Rs is set to a value of 0 when the gear position Gs of the automatic transmission 32 is not being changed, and a positive value is set when the gear position Gs of the automatic transmission 32 is being changed. In this embodiment, the slip ratio Rs during a change in the gear position Gs of the automatic transmission 32 is determined by applying the gear position Gs before the change to a slip ratio map that has been predetermined by experiments or analyses as the relationship between the gear position Gs before the change, the gear position Gs after the change, and the slip ratio Rs, and deriving the corresponding slip ratio Rs from the slip ratio map.

[0026] Once the front inertia J1 is estimated, the torsional primary resonance frequency ftr of the drive shaft DS is estimated based on the estimated front inertia J1 (step S110). Here, the torsional primary resonance frequency ftr of the drive shaft DS is estimated by applying the front inertia J1 to a torsional primary resonance frequency map, which is predetermined by experiments or analyses as the relationship between the front inertia J1 and the torsional primary resonance frequency ftr, and deriving the corresponding torsional primary resonance frequency ftr from the torsional primary resonance frequency map. Figure 3 is an explanatory diagram showing an example of a torsional primary resonance frequency map. As shown in the figure, the torsional primary resonance frequency ftr is determined to be lower as the front inertia J1 increases.

[0027] Then, vibration damping control by the motor 40 is performed to reduce the component of the torsional primary resonant frequency ftr of the drive shaft DS (step S120), and this routine is terminated. Here, vibration damping control by the motor 40 can be performed, for example, by correcting the torque command Tm* of the motor 40 to reduce the component of the torsional primary resonant frequency ftr, setting a corrected torque command Tmco, and controlling the motor 40 (inverter 42) using the set corrected torque command Tmco. The corrected torque command Tmco can be, for example, a value obtained by applying a bandstop filter to the torque command Tm* (filtered torque command). A bandstop filter is a filter that attenuates components in a predetermined frequency range including the torsional primary resonant frequency ftr (for example, the range of torsional primary resonant frequency ftr plus or minus a predetermined value β). This vibration damping control by the motor 40 suppresses the increase in the torsional primary resonance frequency ftr component of the drive shaft DS during the change of the gear stage Gs of the automatic transmission 32, that is, during the slip of the release-side element and the engagement-side element, thereby suppressing increased vehicle vibration.

[0028] In the hybrid vehicle 20 of the embodiment described above, the front inertia J1 is estimated based on the slip ratio Rs of the automatic transmission 32, the torsional primary resonance frequency ftr of the drive shaft DS is estimated based on the estimated front inertia J1, and vibration damping control by the motor 40 is performed to reduce the component of the torsional primary resonance frequency ftr of the drive shaft DS. This makes it possible to more appropriately estimate the torsional primary resonance frequency ftr of the drive shaft DS and suppress the increase in vehicle vibration when the friction engagement elements are slipping, such as when the gear stage Gs of the automatic transmission 32 is being changed.

[0029] In the embodiment described above, the ECU 50 repeatedly executes the processing routine shown in Figure 2, but it is not limited to this. For example, the processing routine shown in Figure 2 may be executed only when the gear position Gs of the automatic transmission 32 is being changed (during slippage of the release-side element and the engagement-side element). In this case, when the gear position Gs of the automatic transmission 32 is not being changed, vibration damping control by the motor 40 may be performed by well-known processes different from each process of the processing routine shown in Figure 2.

[0030] In the embodiment described above, the rotor shaft of the motor 40 is connected to the output shaft 34 of the automatic transmission 32 and also to the drive shaft 46, but the embodiment is not limited to this. For example, the output shaft 34 of the automatic transmission 32 may be directly connected to the drive shaft 46, and the rotor shaft of the motor 40 may be connected to the drive shaft 46 via a gear mechanism or the like.

[0031] In the embodiment described above, the motor 40 is provided between the automatic transmission 32 and the drive shaft 46, but it is not limited to this. For example, the motor 40 may be provided between the differential gear DF ​​and the drive shaft DS.

[0032] In the embodiments described above, the hybrid vehicle 20 is provided with an engine 22, a power transmission device 30, and a motor 40, but it is not limited to this. For example, in addition to a hardware configuration similar to that of the hybrid vehicle 20, it may further include a second motor positioned between the engine 22 and the power transmission device 30 and directly connected to the engine 22.

[0033] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be explained. In the embodiment, engine 22 corresponds to "engine", automatic transmission 32 corresponds to "stepped transmission", motor 40 corresponds to "motor", and ECU 50 corresponds to "control device".

[0034] Furthermore, the correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem is merely an example to specifically explain the form in which the embodiment implements the invention described in the section on means for solving the problem, and does not limit the elements of the invention described in the section on means for solving the problem. In other words, the interpretation of the invention described in the section on means for solving the problem should be based on the description in that section, and the embodiment is merely one specific example of the invention described in the section on means for solving the problem.

[0035] Although the embodiments for implementing this disclosure have been described above, this disclosure is not limited in any way to these embodiments, and can of course be implemented in various forms without departing from the gist of this disclosure. [Industrial applicability]

[0036] This disclosure can be used in industries such as the hybrid vehicle manufacturing industry. [Explanation of Symbols]

[0037] 20 Hybrid vehicle, 22 Engine, 23 Crankshaft, 23a Rotation speed sensor, 24 Inverter, 30 Power transmission system, 31 Torque converter, 32 Automatic transmission, 33 Input shaft, 33a Rotation speed sensor, 34 Output shaft, 34a Rotation speed sensor, 40 Motor, 40a Rotation position sensor, 42 Inverter, 43 Input shaft, 44 Battery, 45 Automatic transmission, 46 Drive shaft, 50 ECU, 60 Power switch, 61 Shift lever, 62 Shift position sensor, 63 Accelerator pedal, 64 Accelerator pedal position sensor, 65 Brake pedal, 66 Brake pedal position sensor, 67 Vehicle speed sensor.

Claims

1. A hybrid vehicle comprising an engine, a stepped transmission having multiple friction engagement elements and connected to the engine, a motor provided between the stepped transmission and a drive shaft connected to the drive wheels, and a control device, The control device is Based on the slip ratio of the friction engagement element of the stepped transmission, the front inertia on the engine side of the drive shaft is estimated. Based on the aforementioned front inertia, the torsional primary resonance frequency of the drive shaft is estimated. The motor performs vibration damping control to reduce the component of the torsional primary resonant frequency. Hybrid vehicle.

2. A hybrid vehicle according to claim 1, The control device controls the motor using a filtered torque command obtained by applying a bandstop filter to the motor's torque command to reduce the component of the torsional primary resonance frequency. Hybrid vehicle.

3. A hybrid vehicle according to claim 1, The motor is connected to the stepped transmission and the differential gear connected to the drive shaft. Hybrid vehicle.

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