JP4192898B2 - Hybrid vehicle - Google Patents

Description

  The present invention relates to a hybrid vehicle including an engine and a motor as driving force sources.

  In Patent Document 1, an engine, first and second motor generators, an output gear that outputs driving force to driving wheels, and a brake are connected to five rotating elements of a two-degree-of-freedom differential mechanism for continuously variable transmission. A mechanism to perform (hereinafter referred to as “E-iVT”) is disclosed.

  In the traveling mode in which the brake is released, the continuously variable transmission can be realized by controlling the rotational speeds of the engine and the first and second motor generators. Then, a fixed gear ratio is realized in which the rotation speed of the engine and the rotation speed of the output gear are constant.

Further, a clutch is interposed between the engine and the differential mechanism, and by switching the engagement state of this clutch, a travel mode in which the vehicle travels only with the power of the first and second motors without depending on the power of the engine, It is possible to switch the travel mode in which the vehicle can travel using the power of the engine in addition to the power of the first and second motors.
Japanese Patent Laid-Open No. 2003-32808

  In a vehicle equipped with the E-iVT, the shift control is often performed in accordance with the conventional belt-type CVT shift control. It is set in consideration of power that can be input and output, and the speed change speed is limited so that fluctuations in driving force can be suppressed during speed change.

  However, if the shift speed is limited so as to suppress fluctuations in the driving force during the shift, the shift speed is also limited when the shift is performed in response to a change in the target drive force. It takes time for the driving force to be realized to cause the driver to feel uncomfortable.

  The present invention has been made in view of such technical problems, and is intended to reduce the uncomfortable feeling given to the driver by appropriately setting the shift speed when the target driving force changes in a vehicle equipped with i-IVT. Objective.

A hybrid vehicle according to the present invention includes a two-degree-of-freedom differential mechanism having at least first to fourth rotating elements arranged on a collinear diagram, and an engine connected to each of the first to fourth rotating elements. And an output gear for outputting driving force to the driving wheels, a first motor and a second motor, and the upper limit value of the shifting speed when shifting is performed in response to an increase in the target driving force, the driving force is constant. Is set higher than the upper limit value of the shift speed when shifting is performed under the above conditions.

  By changing the setting method of the shift speed when the target driving force changes and when it is not, it is possible to set the shift speed appropriately, and the rotation speed of the rotating element changes suddenly when shifting, It is possible to reduce a sense of incongruity caused by doing.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows a schematic configuration of a hybrid vehicle according to the present invention. The hybrid vehicle includes a differential mechanism 1 and is configured such that the power of the engine 2, the first motor generator 3, and the second motor generator 4 is transmitted to driving wheels (not shown) via the differential mechanism 1. The first motor generator 3 is disposed inside the second motor generator 4, and the first motor generator 3 and the second motor generator 4 are coaxial multilayer motors sharing a stator.

  The differential mechanism 1 is a Ravigneaux type planetary gear mechanism in which a first planetary gear train 6 and a second planetary gear train 7 are combined. The pinion P1 of the first planetary gear train 6 and the pinion P2 of the second planetary gear train 7 mesh with each other and are supported by a common carrier C (second rotating element).

  The engine 2 is connected to the ring gear R1 (first rotating element) of the first planetary gear train 6 via an engine clutch EC constituted by a hydraulic multi-plate clutch. The first motor generator 3 (more precisely, the rotor of the first motor generator 3) is connected to the sun gear S2 (third rotating element) of the second planetary gear train 7. The second motor generator 4 (more precisely, the rotor of the second motor generator 4) is connected to the sun gear S1 (fourth rotating element) of the first planetary gear train 6.

  An output gear 12 is connected to the common carrier C, and power transmitted to the output gear 12 is transmitted to drive wheels (not shown) via gears 13 and 14, a differential gear 15, and a drive shaft 16.

  The ring gear R2 (fifth rotating element) of the second planetary gear train 7 is provided with a low brake LB. The low brake LB is constituted by a hydraulic multi-plate clutch. When engaged, the low brake LB prevents the rotation of the ring gear R2 and sets the transmission gear ratio of the differential mechanism 1 (the ratio of the rotation speed of the engine 2 and the rotation speed of the output gear 12) to a predetermined value. Fix to low gear ratio.

  The supply of hydraulic pressure to the engine clutch EC and low brake LB is controlled by the hydraulic circuit 17, and the engagement state of the engine clutch EC and low brake LB is controlled by the controller 20 via the hydraulic circuit 17.

  The rotation speed and torque of the engine 2, the first motor generator 3 and the second motor generator 4 are controlled by the controller 20. By controlling the rotational speeds of these power sources, the speed ratio of the differential mechanism 1 can be controlled steplessly in a state where the low brake LB is released. Note that the rotation speed and torque of the first motor generator 3 and the second motor generator 4 are controlled via an inverter 21, and a battery 22 is connected to the inverter 21.

  FIG. 2 is a collinear diagram of the differential mechanism 1. The nomogram shows the rotational speed of each rotating element on the vertical axis, and the relationship of the gear ratio between the rotating elements on the horizontal axis. The ring gear R1 to which the engine 2 is connected and the first motor generator 3 are When the sun gear S2 to be connected, the sun gear S1 to which the second motor generator 4 is connected, the carrier C to which the output gear 12 is connected, and the ring gear R2 to which the low brake LB is provided are represented on a collinear diagram, these rotating elements are Line up on a straight line.

  In a state where the low brake LB is released, if the rotational speed of any two of the rotating elements is determined, the rotational speed of the remaining rotating elements is determined. Therefore, the degree of freedom of the differential mechanism 1 is 2, and the speed of the differential mechanism 1 is changed. The ratio can be set steplessly. On the other hand, the alignment chart in a state where the low brake LB is engaged is as shown in FIG. 3, and in this state, the gear ratio of the differential mechanism 1 is fixed to the low side.

  The controller 20 receives from a sensor (not shown) a signal indicating the driving state of the vehicle such as the rotational speed of the engine 2, the first motor generator 3 and the second motor generator 4, the operation amount of the accelerator pedal, the charging state of the battery 22, and the vehicle speed. And the controller 20 switches the driving mode according to the driving state of the vehicle, and the engine 2 and the first motor generator 3 so that the target driving force set according to the operation amount of the accelerator pedal, the vehicle speed, etc. is realized. And the torque and rotation speed of the second motor generator 4 are controlled.

  The traveling mode is determined based on the vehicle speed and the target driving force with reference to a traveling mode switching map as shown in FIG.

  Each travel mode will be described. In the EV-LB mode, the low brake LB is fastened to fix the gear ratio of the differential mechanism 1 to the low side, and the engine clutch EC is released, and the first motor generator 3 and the second motor. This mode travels only with the power of the generator 4, and is mainly used at the time of starting acceleration. In the LB mode, the low brake LB is engaged to fix the gear ratio of the differential mechanism 1 to the low side and the engine clutch EC is engaged, and the engine 2, the first motor generator 3 and the second motor generator 4 are driven by the power. This mode is mainly used when a large driving force is required at a low vehicle speed.

  Further, the EV mode is a mode in which both the low brake LB and the engine clutch EC are released and the vehicle travels only with the power of the first motor generator 3 and the second motor generator 4. It is also used when the first motor generator 3 and the second motor generator 4 are regeneratively operated. The E-iVT mode is a mode in which the low brake LB is released and the engine clutch EC is engaged and the engine 2, the first motor generator 3 and the second motor generator 4 are driven by the power. It is done.

  When switching the travel mode from the travel mode in which the low brake LB is not engaged (E-iVT mode, EV mode) to the travel mode (LB mode, EV-LB mode) in which the low brake LB is engaged First, a preparatory shift for controlling the rotational speeds of the engine 1, the first motor generator 3 and the second motor generator 4 is performed so that the rotational speed of the ring gear R2 provided with the low brake LB approaches zero, and the ring gear R2 When the rotation speed approaches zero, the low brake LB is engaged. After that, the complete shift is performed until the speed ratio required in the travel mode after switching is reached.

  Conversely, when switching the travel mode from the travel mode in which the low brake LB is engaged to the travel mode in which the low brake LB is not engaged, the low brake LB is released, and the request is made in the switched travel mode. The complete shift is performed until the transmission gear ratio is reached.

  When switching from a travel mode (EV mode, EV-LB mode) in which the engine clutch EC is not engaged to a travel mode (LB mode, E-iVT mode) in which the engine clutch EC is engaged or vice versa In the case of switching, the same shift control is performed.

  If the speed change when the target driving force changes (change speed of the gear ratio, hereinafter the same) is set in the same way as the speed at which shifting is performed under the condition of constant driving force within the same driving mode. However, even if the target driving force increases, the actual driving force increases slowly, and conversely, when the target driving force decreases, the change in the rotational speed of each rotating element accompanying the gear shift is large, which may cause the driver to feel uncomfortable. There is.

  Also, if the shifting speed at the time of switching the driving mode is set to be the same as the shifting speed at the time of shifting within the same driving mode, the fluctuation of the driving force can be suppressed, but the switching of the driving mode becomes slow and the desired driving force is reduced. There is a possibility that the driver may feel uncomfortable because it is difficult to obtain, or that the charging / discharging power control may be delayed.

  Therefore, in the hybrid vehicle according to the present invention, the shift speed control as described below is performed.

  FIG. 5 is a flowchart showing the contents of the shift speed control performed by the controller 2.

  This will be described. First, in step S1, an upper limit value DLIM1 of the shift speed set depending on whether or not the traveling mode is being switched is set. The shift speed upper limit DLIM1 is set according to the flowchart shown in FIG. 6, which will be described later.

  In step S2, a shift speed upper limit DLIM2 is set, which is set depending on whether the target driving force is changing. The shift speed upper limit DLIM2 is set according to the flowchart shown in FIG. 7, which will be described later.

  In step S3, the shift speed upper limit DLIM1 set in step S1 is compared with the shift speed upper limit DLIM2 set in step S2, and the smaller one is set as the shift speed upper limit DLIM.

  In step S4, the speed change speed of the differential mechanism 1 set in accordance with the difference between the target speed ratio set in accordance with the driving state of the vehicle and the driving mode and the current speed ratio is changed to the speed set in step S3. Limited by speed upper limit DLIM.

  In step S <b> 5, the rotational speeds of the engine 1, the first motor generator 3, and the second motor generator 4 are controlled so that the shift is performed at the limited shift speed.

  FIG. 6 is a flowchart for setting the shift speed upper limit DLIM1.

  According to this, first, in step S11, it is determined whether or not the traveling mode is being switched. If it is determined that switching is being performed, the process proceeds to step S12. If it is not determined that switching is in progress, the process proceeds to step S18, and the shift speed upper limit DLIM1 is set to the standard shift speed upper limit Ds. The standard shift speed upper limit Ds is a value set in consideration of the responsiveness of the engine 1, the first motor generator 3, and the second motor generator 4 when shifting is performed under the condition of constant driving force in the same travel mode. It is.

  In step S12, switching from the driving mode in which the engine clutch EC is released to the driving mode in which the engine clutch EC is engaged is switched to the driving mode in which the engine clutch EC is engaged, or from the driving mode in which the low brake LB is released to the low brake. It is determined whether it corresponds to any one of the switching to the traveling mode in which the vehicle travels with the LB engaged. When it corresponds to either, it progresses to step S13, and when it does not correspond to any, it progresses to step S16.

  In step S13, before engaging the engine clutch EC or the low brake LB, it is determined whether or not a preparatory shift in which the rotational speed difference between these elements is close to zero is being performed. If it is determined that the preparatory shift is being performed, the process proceeds to step S14. If not, the process proceeds to step S15.

  In step S14, the shift speed upper limit DLIM1 is set to a predetermined value D1. The predetermined value D1 is a value larger than the standard shift speed upper limit Ds.

  In step S15, the shift speed upper limit DLIM1 is set to a predetermined value D2. The predetermined value D2 is a value smaller than the standard shift speed upper limit Ds.

  On the other hand, when the process proceeds from step S12 to step S16, switching from the traveling mode in which the engine clutch EC is engaged to the traveling mode in which the engine clutch EC is released, or the low brake LB is engaged. It is determined whether it corresponds to one of the switching from the running mode running in the state to the running mode running in the state where the low brake LB is released. If any of these conditions is satisfied, the process proceeds to step S17. Otherwise, the process proceeds to step S18, and the shift speed upper limit DLIM is set to the standard shift speed upper limit Ds.

  In step S17, the shift speed upper limit DLIM is set to a predetermined value D3. The predetermined value D3 is a value smaller than the standard shift speed upper limit Ds.

  FIG. 7 is a flowchart for setting the shift speed upper limit DLIM2.

  According to this, first, in step S21, it is determined whether or not the target driving force has changed, and if it has changed, it is further determined whether it has increased or decreased. When the target driving force increases, the process proceeds to step S22. When the target driving force decreases, the process proceeds to step S23, and when there is no change, the process proceeds to step S24.

  In step S22, the shift speed upper limit DLIM2 is set to a predetermined value D4. The predetermined value D4 is a value larger than the standard shift speed upper limit Ds.

  In step S23, the shift speed upper limit DLIM2 is set to a predetermined value D5. The predetermined value D5 is a value smaller than the standard shift speed upper limit Ds.

  In step S24, the shift speed upper limit DLIM2 is set to the standard shift speed upper limit Ds.

  Next, the effect | action by performing the said transmission speed control is demonstrated.

  In the hybrid vehicle according to the present invention, when shifting is performed in response to an increase in the target driving force, the upper limit of the shifting speed is set to a larger value than the normal shifting speed upper limit Ds, so that the shifting speed increases. The time from when the force increases until the actual driving force increases can be shortened. The standard shift speed upper limit Ds is an upper limit value of the shift speed when shifting is performed in the same traveling mode under a constant driving force, and takes into account the responsiveness of the engine 2, the first motor generator 3, and the second motor generator 4. The value to be set.

  On the contrary, when shifting is performed in response to a decrease in the target driving force, the upper limit of the shift speed is set to a value smaller than the normal shift speed upper limit Ds, and the shift speed becomes smaller. It is possible to reduce a sense of incongruity due to a sudden change in the rotational speed of the element, that is, the gear ratio.

  Furthermore, in the hybrid vehicle according to the present invention, the traveling mode (LB mode, E-) in which the engine clutch EC is engaged from the traveling mode (EV mode, EV-LB mode) in which the engine clutch EC is released. When the travel mode is switched to the iVT mode), first, the first motor generator 3 and the second motor generator 4 rotate so as to reduce the rotational speed difference in the engine clutch EC, that is, the rotational speed difference between the engine 2 and the ring gear R1. Perform a preparatory shift to control the speed. When the difference in rotational speed between the engine 2 and the ring gear R1 approaches zero, the engine clutch EC is engaged, and a complete shift is performed until the speed ratio required in the travel mode after switching is reached.

  In the preparation shift, the upper limit of the shift speed is set to a predetermined value D1 larger than the standard shift speed upper limit Ds, so that the shift speed increases. Conversely, in the completed shift, the upper limit of the shift speed is higher than the standard shift speed upper limit Ds. Is also set to a small predetermined value D2, so that the shift speed is reduced. The standard shift speed upper limit Ds is an upper limit value of the shift speed when shifting is performed in the same traveling mode under a constant driving force, and takes into account the responsiveness of the engine 2, the first motor generator 3, and the second motor generator 4. Is set.

  By setting the shift speed in this way, the driving force may fluctuate during the preparation shift until the engine clutch EC is engaged, but the time until the engine clutch EC is engaged is reduced. Can do. The engine clutch EC is engaged when generating a large driving force using the power of the engine 2 or when generating power by driving the first motor generator 3 or the second motor generator 4 with the power of the engine 2. Therefore, by shortening the time until the engine clutch EC is engaged, it is possible to prevent a sense of incongruity due to a delay in the generation of the driving force and a control delay in the charge / discharge power.

  Further, in the completed shift after the engagement of the engine clutch EC, the shift speed is suppressed and the shift is gradually performed. As a result, it is possible to reduce a sense of incongruity due to a sudden change in the rotational speed of each rotary element of the differential mechanism 1, that is, the gear ratio. Although the gear shift is performed so as not to change the driving force at the completion gear shift, there is a possibility that a driving force change due to an inertia error may occur. However, the gear shift speed at the completion gear shift should be suppressed and a gentle gear shift should be performed. Thus, the uncomfortable feeling that the driving force change gives to the driver can be reduced.

  Even when the travel mode is switched to a travel mode (EV mode, E-iVT mode) that travels with the low brake LB released or a travel mode (LB mode, EV-LB mode) that travels with the low brake LB engaged. Similar shift speed control is performed, and it is possible to prevent a sense of incongruity due to a delay in the generation of driving force and a delay in control of charge / discharge power due to a delay in traveling mode switching.

  Furthermore, in the hybrid vehicle according to the present invention, the travel mode is changed from the travel mode in which the engine clutch EC (or low brake LB) is engaged to the travel mode in which the engine clutch EC (or low brake LB) is released. When switching the gear, the shift speed upper limit is set to a value smaller than the normal shift speed limit Ds, and the complete shift is performed. In the complete shift, the speed is changed to the required speed ratio after switching the travel mode, so that the rotational speed of each rotating element changes. However, the discomfort given to the driver can be reduced by suppressing the shift speed in the complete shift. it can.

1 is a schematic configuration diagram of a hybrid vehicle according to the present invention. It is an alignment chart of a differential mechanism, and shows the state where a low brake is released. It is a collinear diagram of a differential mechanism and shows a state in which a low brake is engaged. It is a travel mode switching map. It is the flowchart which showed the content of speed change speed control. 5 is a flowchart for setting a shift speed upper limit DLIM1. 5 is a flowchart for setting a shift speed upper limit DLIM2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Differential mechanism 2 Engine 3 1st motor generator (1st motor)
4 Second motor generator (second motor)
6 First planetary gear train 7 Second planetary gear train 12 Output gear 20 Controller EC Engine clutch LB Low brake C Carrier S1, S2 Sun gear P1, P2 Planetary gear R1, R2 Ring gear

Claims (9)

A two-degree-of-freedom differential mechanism having at least first to fourth rotating elements arranged on a nomographic chart, and an engine and driving wheels connected to the first to fourth rotating elements, respectively. An output gear for outputting, a first motor, and a second motor, and controlling at least one rotational speed of the first motor, the second motor, and the engine to control the rotational speed of the engine and the output In a hybrid vehicle that can change the gear ratio, which is the ratio of the rotational speeds of the gears, steplessly,
The upper limit value of the shift speed when performing a shift in response to an increase in the target driving force is set to be higher than the upper limit value of the shift speed when performing a shift with the constant driving force within the same travel mode. A featured hybrid vehicle. The upper limit value of the shift speed when performing a shift in response to a decrease in the target driving force is set lower than the upper limit value of the shift speed when performing a shift under the condition of a constant driving force within the same travel mode. The hybrid vehicle according to claim 1. An engine clutch interposed between the first rotating element and the engine;
  When the travel mode is switched from the travel mode in which the engine clutch is disengaged to the travel mode in which the engine clutch is engaged, a preparatory shift is performed so as to reduce the rotational speed difference in the engine clutch; A shift control means for engaging the engine clutch when the rotational speed difference in the clutch is reduced, and then performing a complete shift to the speed ratio required in the travel mode after switching,
With
  3. The hybrid vehicle according to claim 1, wherein an upper limit value of a shift speed in the preparation shift is set to be higher than an upper limit value of a shift speed when shifting is performed in the same travel mode. 4. The hybrid vehicle according to claim 3, wherein an upper limit value of a shift speed in the completion shift is set lower than an upper limit value of a shift speed when shifting is performed in the same traveling mode. The shift control means releases the engine clutch and switches the engine clutch in the same travel mode when switching the travel mode from the travel mode in which the engine clutch is engaged to the travel mode in which the engine clutch is released. 5. The hybrid vehicle according to claim 3, wherein the speed change is performed at a speed lower than an upper limit value of the speed change speed when the speed is changed to a speed ratio required in the travel mode after switching. A fifth rotating element arranged on the collinear diagram;
  A brake for a fixed gear ratio provided on the fifth rotating element;
  When the travel mode is switched from the travel mode in which the fixed speed ratio brake is released to the travel mode in which the fixed speed ratio brake is engaged, the rotational speed difference in the fixed speed ratio brake is reduced. The gear shift is performed so that the fixed gear ratio brake is engaged when the rotational speed difference in the fixed gear ratio brake is reduced, and then the completed gear shift is performed to the gear ratio required in the travel mode after switching. Control means;
With
  The hybrid vehicle according to claim 1, wherein an upper limit value of a shift speed in the preparation shift is set higher than an upper limit value of a shift speed when shifting is performed in the same travel mode. The hybrid vehicle according to claim 6, wherein an upper limit value of a shift speed in the completion shift is set lower than an upper limit value of a shift speed when shifting is performed in the same traveling mode. The shift control means, when switching the travel mode from a travel mode that travels with the fixed gear ratio brake engaged to a travel mode that travels with the fixed gear ratio brake released, And the transmission speed is limited to the upper limit value of the transmission speed that is lower than the upper limit value of the transmission speed when shifting in the same driving mode, and then the speed is changed to the speed ratio required in the changed driving mode. The hybrid vehicle according to claim 6, wherein the hybrid vehicle is performed. The upper limit value of a shift speed when performing a shift while traveling in the same travel mode is an upper limit value of a shift speed when performing a shift with a constant driving force in the same travel mode. The hybrid vehicle according to any one of 3 to 8.

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