JP2009180271A - Vehicle shift control device and shift control method - Google Patents

Abstract

[PROBLEMS] To prevent a shift shock during a foot-shift.
An accelerator opening degree is provided in a vehicle shift control device including a sub-transmission 8 having a clutch 16 for switching between a high-speed stage and a low-speed stage, and a main transmission 6 to which rotation from the sub-transmission is input. An accelerator opening detecting means 48 for detecting the shift, a shift request detecting means 30 for detecting a shift request from the low speed stage to the high speed stage of the auxiliary transmission, and a shift request from the low speed stage to the high speed stage of the auxiliary transmission. If the accelerator opening is zero and the engine speed is zero, the engine speed control controls the engine speed below the target engine speed calculated based on the shift diagram of the main transmission corresponding to the high speed stage of the sub-transmission. Means 30.
[Selection] Figure 1

Description

  The present invention relates to a shift control device and a shift control method for a vehicle having an auxiliary transmission.

2. Description of the Related Art An automatic transmission of a vehicle is known in which a sub-transmission is provided instead of a torque converter (see Patent Documents 1 and 2). The sub-transmission transmits engine rotation to a continuously variable transmission or the like that is a main transmission, and includes a planetary gear mechanism, a clutch (high-speed clutch), and a one-way clutch. The planetary gear mechanism generates a torque ratio instead of a torque converter. Further, the shift of the auxiliary transmission is performed based on a specified shift map (see Patent Document 3).
JP 2003-35353 A JP 2005-163953 A JP 2002-340163 A

  However, at the first speed (low speed stage), the auxiliary transmission fixes the ring gear of the planetary gear mechanism with a one-way clutch, inputs the engine torque to the sun gear, and transmits the engine torque with the carrier output. At the second speed (high speed stage), the sun gear and the carrier are engaged with each other by a clutch, whereby the sun gear and the carrier are synchronously rotated to transmit the engine torque. Further, the interstage ratio between the first speed and the second speed (ratio of the reduction ratio between the first speed and the second speed) is large.

  For this reason, when the sub-transmission shifts from the first speed to the second speed by foot-shifting, if the engine speed is higher than the input speed to the continuously variable transmission and the sub-transmission clutch is engaged, the speed change will occur. A shock occurs. The foot release speed change is a speed change during coasting where the accelerator pedal is released and the accelerator opening APO (throttle opening TVO) is set to zero.

  In addition, when the sub-transmission shifts with a foot off, if the clutch of the sub-transmission is engaged when the engine speed is significantly lower than the input speed to the continuously variable transmission, sudden engine braking occurs or engine braking occurs. Changes in the strength of

  The present invention has been made in view of such problems, and an object of the present invention is to prevent a shift shock or a sudden engine brake change during a foot-shift.

  An accelerator opening degree is detected in a shift control device for a vehicle, comprising: a sub-transmission having a planetary gear mechanism, a clutch for switching between a high speed stage and a low speed stage; and a main transmission to which rotation from the sub transmission is input. When there is a shift request from the low speed stage to the high speed stage of the auxiliary transmission, a shift request detection means to detect a shift request from the low speed stage to the high speed stage of the auxiliary transmission, Clutch control means for controlling the clutch to execute a shift from the low speed stage to the high speed stage of the auxiliary transmission, and there is a shift request from the low speed stage to the high speed stage of the auxiliary transmission and the accelerator opening is zero. In some cases, engine speed control means for controlling the engine speed below a target engine speed calculated based on a shift diagram of the main transmission corresponding to the high speed stage of the sub-transmission is provided. The features.

  According to the present invention, by appropriately controlling the engine rotational speed at the time of foot-shifting, it is possible to perform a smooth shift while suppressing a shock during the shift.

  FIG. 1 is a diagram showing an entire vehicle to which the present invention is applied. In the vehicle, the automatic transmission 1 transmits the driving force of the engine 2 to the drive wheels 4. The automatic transmission 1 includes a continuously variable transmission (CVT) 6 that is a main transmission and an auxiliary transmission 8. The continuously variable transmission 6 includes a forward / reverse switching mechanism and a continuously variable transmission mechanism, and may be either a belt-type continuously variable transmission or a toroidal continuously variable transmission.

  The auxiliary transmission 8 includes a planetary gear mechanism 18 and a clutch (high speed stage selection clutch) 16 that switches between a high speed stage and a low speed stage. For example, Patent Documents 1 and 2 (Japanese Patent Laid-Open No. 2003-35353) The same as in JP 2005-163953 A may be used. The planetary gear mechanism 18 is a normal planetary gear mechanism including a ring gear 18r, a sun gear 18s, a pinion gear 18p, a carrier 18c, and the like. The ring gear 18r is prevented from rotating in the direction opposite to the rotation of the engine output shaft (engine output shaft) 22 by the one-way clutch 19 for fixing. The carrier 18c is directly connected to the sub-transmission output shaft (input shaft of the continuously variable transmission) 24.

  The clutch 16 is interposed between the carrier 18c and the engine output shaft 22. When the clutch 16 is completely disengaged at the first speed (low speed) of the sub-transmission 8, the continuously variable transmission 6 is coupled to the engine output shaft 22 via the sun gear 18s and the pinion gear 18p, thereby A reduction ratio (greater than 1) of the low speed stage of the machine 8 is realized. In the first speed, torque is transmitted in the order of the engine 2, the sun gear 18s, the carrier 18c, the continuously variable transmission 6, the F / D (final gear / differential gear), and the drive wheels 4. In the first speed, when the vehicle is in a release coasting state where the accelerator opening (the amount of depression of the accelerator pedal) APO becomes zero during traveling, the one-way clutch 19 is disengaged and the engine brake does not work.

  In the second speed (high speed stage) of the auxiliary transmission 8, when the clutch 16 is completely engaged, the engine output shaft 22 and the carrier 18c are directly connected, and the continuously variable transmission 6 and the engine 2 can be directly connected. In the direct connection state, the sun gear 18s, the carrier 18c, and the ring gear 18r rotate synchronously, and the engine rotation speed (that is, the rotation speed of the engine output shaft 22) and the input rotation speed of the continuously variable transmission (that is, the continuously variable transmission input shaft). 24), and the reduction gear ratio (usually 1) of the high speed stage of the auxiliary transmission 8 is realized. In the second speed, torque is transmitted in the order of the engine 2, the clutch 16, the carrier 18c, the continuously variable transmission 6, the F / D (final gear / differential gear), and the drive wheels 4. In the second speed, the engine brake is effective even in a foot-off coast state where the accelerator opening APO becomes zero during traveling.

  When the clutch 16 is in the slip state between the fully engaged state and the fully released state, the reduction ratio of the sub-transmission 8 is a reduction ratio between the low speed gear ratio and the high speed gear ratio.

  The controller 30 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a timer, an input / output interface, and the like, and controls the automatic transmission 1 and the engine 2. . In the present embodiment, an engine control unit and an automatic transmission control unit that share various types of information through communication lines are collectively used as the controller 30. The ROM of the controller 30 stores and stores a map and the like described later.

  The controller 30 performs the engagement, release, or slip control of the clutch 16 and the gear ratio control of the continuously variable transmission 6 via a hydraulic system (control valve body) 32 that supplies hydraulic pressure to the continuously variable transmission 6 and the clutch 16. Execute. The controller 30 includes a vehicle speed signal from a vehicle speed sensor 40 (which may be a wheel speed sensor or the like) that detects a vehicle speed VSP of the vehicle, an engine speed signal from an engine speed sensor 44 that detects an engine speed, and a continuously variable transmission. 6, an input rotational speed signal from a continuously variable transmission input rotational speed sensor 46 that detects an input rotational speed 6 (continuously variable transmission input rotational speed), and a continuously variable transmission output that detects an output rotational speed of the continuously variable transmission 6. An output rotational speed signal from the rotational speed sensor 47, an APO signal from an accelerator opening sensor 48 (which may be a throttle opening sensor) for detecting the accelerator opening APO, and the like are input. Any one of the vehicle speed sensor 40 and the continuously variable transmission output rotational speed sensor 47 may be omitted.

  With reference to the flowchart of FIG. 2 and the time chart of FIG. 3, the shift control executed by the controller 30 when the sub-transmission shifts from the first speed (low speed stage) to the second speed (high speed stage) while the vehicle is running will be described. To do.

  In step S1, it is determined whether or not a shift request (or shift command) from the first speed to the second speed of the auxiliary transmission is generated. Based on the shift map (shift diagram) of the auxiliary transmission as shown in FIG. 4 stored in the ROM of the controller 30, the first speed (low speed stage) to the second speed (high speed) according to the vehicle speed VSP and the accelerator opening APO. Is determined whether or not there is a shift request of the sub-transmission to the (stage). When the vehicle speed VSP and the accelerator opening APO change from the first speed region to the second speed region, it is determined that there is a shift request for the auxiliary transmission. If no speed change request has occurred, the first speed travel is continued (step S2). If a shift request has occurred, the process proceeds to step S3.

  In step S3, it is determined whether or not it is a foot release speed change, that is, whether or not the accelerator opening APO is zero. If it is not the foot shift, normal shift control is performed (step S4). If it is a foot shift (corresponding to time T1 in FIG. 3), the process proceeds to step S5.

  In step S5, the engine speed is controlled to be equal to or lower than the target engine speed calculated from the vehicle speed VSP and the target speed ratio of the continuously variable transmission 6. Specifically, the final engine target is obtained by subtracting a predetermined rotational speed (for example, 50 rpm to 100 rpm) from the target engine rotational speed calculated from the vehicle speed VSP and the target speed ratio of the continuously variable transmission 6. The engine speed is set as the rotational speed, and the actual engine rotational speed is controlled to the final target rotational speed of the engine. The ROM of the controller 30 includes a shift map of the continuously variable transmission (a shift diagram corresponding to the low speed stage of the sub-transmission) used when the sub-transmission 8 is at the first speed, and a sub-shift. The shift map of the continuously variable transmission shown in FIG. 5 (b) used when the machine 8 is in the second speed (shift diagram corresponding to the high speed stage of the sub-transmission) is stored. In step S5, FIG. Based on the shift map for the second speed in b), the target gear ratio of the continuously variable transmission 6 is calculated from the vehicle speed VSP and the accelerator opening APO (= 0). For the same accelerator opening APO and vehicle speed VSP, the low speed side shift map (reduction ratio) of the 2nd speed shift map of FIG. 5 (b) is larger than the 1st speed shift map of FIG. 5 (a). give. Next, the target engine rotational speed at the second speed (equal to the target input rotational speed of the continuously variable transmission 6) is calculated as the target engine rotational speed from the vehicle speed VSP and the target speed ratio of the continuously variable transmission 6. Further, a value obtained by subtracting a predetermined rotational speed from the target engine rotational speed is set as the final target rotational speed of the engine.

  In step S5, the target continuously variable transmission input rotational speed is calculated from the vehicle speed VSP and the accelerator opening APO (= 0) based on the 2-speed shift map of FIG. The target engine rotational speed may be calculated by multiplying the transmission input rotational speed by the speed ratio (= 1) at the second speed of the sub-transmission, and the engine rotational speed may be controlled below the target engine rotational speed. As engine speed control, known engine speed control such as fuel injection amount control, spark plug ignition timing control, idle speed control valve control, and the like can be used.

  In this way, in the case of a shift by foot separation, the actual engine rotation speed is controlled to the target rotation speed calculated from the current vehicle speed VSP and the target transmission gear ratio of the continuously variable transmission 6. In the foot-off coast state, the one-way clutch 19 is disengaged and the ring gear 18r can rotate, so that the engine rotation speed can be controlled independently of the continuously variable transmission input rotation speed. Conventionally, engine rotational speed control has not been performed at the time of foot-shifting, but by performing control to reduce the engine rotational speed, a sudden change in inertia at the time of shifting can be suppressed, and smooth shifting can be performed without shock. Further, since the engine rotational speed is controlled to a target rotational speed that is lower by a predetermined rotational speed from the target engine rotational speed calculated from the vehicle speed VSP and the accelerator opening APO based on the shift map, the driving force as shown in FIG. Becomes a deceleration side (minus) and a deceleration force is generated, and a gear shift that does not give the driver a sense of incongruity when the foot is released and coasted can be performed.

  The predetermined rotation speed may be determined according to the vehicle speed VSP based on a map or the like, and may be increased as the vehicle speed VSP increases. The predetermined rotation speed may be determined according to the oil temperature of the hydraulic system 32 based on a map or the like. For this reason, the controller 30 receives an oil temperature signal from an oil temperature sensor (not shown). Thus, a deceleration force can be appropriately generated according to the vehicle speed and the oil temperature.

  Next, in step S6, it is determined whether or not the current engine speed is lower than the engine speed at the start of the foot release shift (when the accelerator opening APO is zero). In step S3, it is assumed that the engine speed at the time when the accelerator opening APO becomes zero is stored in the RAM. If the current engine rotation speed is released and the engine rotation speed is not lower than the engine rotation speed at the start of shifting, step S6 is repeated until the current engine rotation speed is released and the engine rotation speed is decreased below the engine rotation speed at the start of shifting. If the current engine speed is lower than the engine speed at the start of shifting, the process proceeds to step S7.

  In step S7, the gear ratio of the continuously variable transmission 6 is controlled to the target gear ratio via the hydraulic system 32. This target speed ratio is the target speed ratio of the continuously variable transmission 6 obtained from the speed change map for the second speed (FIG. 5B) in step S5. As a result, at time T2 in FIG. 3, the gear ratio of the continuously variable transmission 6 begins to change to the low side, and the input rotational speed of the continuously variable transmission 6 begins to increase.

  Next, in step S8, it is determined whether or not the engine speed has reached the target speed. If the engine rotational speed is not equal to the target rotational speed, the process returns to step S5, and control of the engine rotational speed is continued. When the engine rotational speed reaches the target rotational speed (time T3 in FIG. 3), the process proceeds to step S9.

  In step S9, it is determined whether the engine speed is lower than the continuously variable transmission input speed. If the engine rotational speed is greater than the continuously variable transmission input rotational speed, the process returns to step S7 and the control of the transmission ratio of the continuously variable transmission 6 is continued. When the engine rotation speed is lower than the continuously variable transmission input rotation speed (T4 in FIG. 3), the process proceeds to step S10.

  In step S10, the hydraulic pressure of the clutch 16 is increased to a predetermined hydraulic pressure (for example, the hydraulic pressure until the clutch starts to move) to prepare for the clutch 16 to be engaged. This hydraulic precharge can improve the response of the clutch 16 when a clutch engagement command is issued. Further, since the engine rotation speed is lower than the continuously variable transmission input rotation speed, the driving force becomes negative, a deceleration force starts to be generated, and a shift that does not give the driver a sense of incongruity in the foot-off coast state can be performed. When the engine rotation speed is higher than the continuously variable transmission input rotation speed and the clutch hydraulic pressure is increased to start the engagement, a positive driving force is generated, which gives the driver a sense of incongruity.

  Next, in step S11, it is determined whether or not the speed ratio of the continuously variable transmission 6 has reached the target speed ratio. The gear ratio is obtained from the ratio between the input rotation speed and the output rotation speed of the continuously variable transmission 6. If the continuously variable transmission 6 does not reach the target gear ratio, the process returns to step S7 and the control of the gear ratio of the continuously variable transmission 6 is continued. When the continuously variable transmission 6 reaches the target gear ratio (time T5 in FIG. 3), the process proceeds to step S12.

  In step S12, the clutch 16 is gently engaged. As a result, the engine rotation speed and the continuously variable transmission input rotation speed begin to approach each other.

  Next, in step S13, it is determined whether or not the difference between the continuously variable transmission input rotational speed and the engine rotational speed is equal to or less than a specified value (for example, 30 rpm). When the difference is larger than the specified value, the process returns to step S12 and the engagement of the clutch 16 is continued. When the difference between the continuously variable transmission input rotational speed and the engine rotational speed is equal to or less than the specified value (time T6 in FIG. 3), the process proceeds to step S14.

  In step S14, the control of the engine rotation speed is terminated, and then in step S15, the clutch hydraulic pressure is rapidly increased so that the clutch 16 is completely engaged.

  Next, in step S16, it is determined whether or not the continuously variable transmission input rotational speed is equal to the engine rotational speed. If they are not the same, the process returns to step S15 to continue increasing the clutch hydraulic pressure. If they are the same (time T7 in FIG. 3), the shift control is terminated.

  In the above, step S1 constitutes a shift request detecting means, steps S10, S12, and S15 constitute clutch control means, steps S5 and S8 constitute engine rotational speed control means, and steps S7 and S11 constitute gear ratio control means. .

  It goes without saying that the present invention is not limited to the above-described embodiments, and includes various modifications and improvements that can be made within the scope of the technical idea.

1 is an overall view of a vehicle to which the present invention is applied, and shows a configuration of a transmission control device. It is a flowchart which shows the control which the transmission control apparatus by this invention performs. It is a time chart which illustrates the mode of control which shift control device by the present invention performs. It is a shift map (shift diagram) of an auxiliary transmission. (A) It is a shift map (shift diagram) of a continuously variable transmission used when the sub-transmission is at the first speed. (B) A shift map (shift diagram) of a continuously variable transmission used when the sub-transmission is in second speed.

Explanation of symbols

1 automatic transmission 2 engine 6 continuously variable transmission (main transmission)
8 Sub-transmission 16 Clutch 18 Planetary gear mechanism 19 One-way clutch 22 Engine output shaft 24 Continuously variable transmission input shaft 30 Controller 32 Hydraulic system 40 Vehicle speed sensor 44 Engine rotational speed sensor 46 Continuously variable transmission input rotational speed sensor 47 Continuously variable transmission Output speed sensor 48 Accelerator position sensor (Accelerator position detector)

Claims (6)

In a transmission control apparatus for a vehicle, comprising: a sub-transmission having a planetary gear mechanism, a clutch that switches between a high-speed stage and a low-speed stage; and a main transmission that receives rotation from the sub-transmission.
An accelerator opening detecting means for detecting the accelerator opening;
Shift request detecting means for detecting a shift request from a low speed stage to a high speed stage of the sub-transmission;
Clutch control means for controlling the clutch to execute a shift from the low speed stage to the high speed stage of the sub transmission when there is a shift request from the low speed stage to the high speed stage of the sub transmission;
The target calculated based on the shift diagram of the main transmission corresponding to the high speed stage of the auxiliary transmission when there is a shift request from the low speed stage to the high speed stage of the auxiliary transmission and the accelerator opening is zero. An engine speed control means for controlling the engine speed below the engine speed;
A shift control apparatus comprising:   The shift control apparatus according to claim 1, wherein the engine rotation speed control means controls the engine rotation speed to a rotation speed obtained by subtracting a predetermined rotation speed from the target engine rotation speed. When there is a shift request from the low speed stage to the high speed stage of the auxiliary transmission, the gear ratio of the main transmission is calculated based on the shift diagram of the main transmission corresponding to the high speed stage of the auxiliary transmission. A gear ratio control means for controlling to the target gear ratio,
2. The transmission control apparatus according to claim 1, wherein the clutch control means starts to engage the clutch when the transmission gear ratio of the main transmission becomes the target transmission gear ratio.   The speed change control device according to claim 1, wherein the engine speed control means makes the engine speed lower than an input speed of the main transmission.   5. The shift control device according to claim 4, wherein when the engine rotation speed becomes lower than the input rotation speed of the main transmission, the clutch control means increases the hydraulic pressure of the clutch to a predetermined hydraulic pressure. A vehicle shift control method comprising: a sub-transmission having a planetary gear mechanism and a clutch for switching between a high speed stage and a low speed stage; and a main transmission to which rotation from the sub transmission is input.
Detecting the accelerator opening;
Detecting a shift request from the low speed stage to the high speed stage of the auxiliary transmission;
The target calculated based on the shift diagram of the main transmission corresponding to the high speed stage of the auxiliary transmission when there is a shift request from the low speed stage to the high speed stage of the auxiliary transmission and the accelerator opening is zero. A step of controlling the engine speed below the engine speed;
When there is a shift request from the low speed stage to the high speed stage of the auxiliary transmission, controlling the clutch to execute a shift from the low speed stage to the high speed stage of the auxiliary transmission; and
A shift control method comprising:

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