JP2017125548A - Gear change control device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gear change control device of a vehicle which can suppress or avoid that noise is generated because a dog clutch cannot be engaged, and a shock is generated even if the dog clutch is engaged when making the dog clutch engage accompanied by a change of a gear change stage caused by deceleration.SOLUTION: A gear change control device of a vehicle comprises an engine 4, a stepped automatic transmission 1 connected to an output side of the engine 4, and a dog clutch B2 which is engaged in order to set a prescribed gear change stage by the stepped automatic transmission 1. The gear change control device of a vehicle sets the prescribed gear change stage when a vehicle speed reaches a prescribed vehicle speed or lower, and also comprises a controller 14 for controlling the stepped automatic transmission 1. In the case where the deceleration of the vehicle when the vehicle speed reaches the prescribed vehicle speed or lower is larger than preset prescribed deceleration, the controller 14 prohibits a downshift to the prescribed gear change stage.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle shift control device that can change a gear ratio stepwise, and more particularly to a vehicle shift control device that uses a dog clutch as an engagement mechanism for setting a predetermined gear position. .

  Patent Document 1 describes an automatic transmission for a vehicle including a planetary gear mechanism. The vehicular automatic transmission is configured to set a reverse gear by fixing one rotating element in a planetary gear mechanism by engaging a dog clutch. Further, the dog clutch is configured to be used only when the reverse gear is set, and a friction engagement member that is engaged prior to the engagement of the dog clutch is provided.

Japanese Patent Laid-Open No. 10-89421

  In the stepped automatic transmission, the gear position is set stepwise according to the vehicle speed and the accelerator opening. For example, when the vehicle speed becomes low due to coasting or the like, the high-speed gear stage is downshifted to the low-speed gear stage according to the vehicle speed. The gear position after the downshift may be set by engaging a dog clutch. In such a case, for example, when the vehicle suddenly decelerates due to the driver's brake operation, etc., the change in the differential rotational speed between the input side and the output side of the dog clutch becomes large, so the rotational speeds of each other cannot be synchronized. There is a risk of trying to engage. If the rotation speeds are not synchronized, ratcheting may occur and the dog clutch may not be engaged.

  Therefore, in the configuration of Patent Document 1, a friction engagement member that is engaged prior to the engagement of the dog clutch is provided. The friction engagement member is configured to stop the relative rotation between the input side and the output side of the dog clutch when engaged. However, this frictional engagement member is provided to suppress relative rotation due to rotation of the dog clutch via the lubricating oil when the dog clutch is engaged. That is, with this friction engagement member, the relative rotation occurring on the input side and output side of the dog clutch at the time of sudden deceleration cannot be sufficiently suppressed, and there is a possibility that the rotation speed of the dog clutch cannot be synchronized. Therefore, there is a possibility that the dog clutch cannot be engaged and an abnormal noise is generated or a shock is generated even when the dog clutch is engaged.

  The present invention has been made paying attention to the technical problem described above, and when engaging the dog clutch in association with the change of the gear stage due to the deceleration, the dog clutch cannot be engaged and abnormal noise is generated. It is an object of the present invention to provide a vehicle shift control device that can suppress or avoid the occurrence of a shock even when combined.

  In order to achieve the above object, the present invention is engaged with an engine, a stepped automatic transmission connected to the output side of the engine, and a stepped automatic transmission for setting a predetermined shift stage. And a controller for controlling the stepped automatic transmission, wherein the controller is configured to set the predetermined gear position when the vehicle speed falls below a predetermined vehicle speed. Is configured to prohibit a downshift to the predetermined shift stage when the deceleration of the vehicle when the vehicle speed is equal to or lower than the predetermined vehicle speed is greater than a predetermined deceleration. It is characterized by.

  According to the present invention, when the vehicle speed becomes lower than the predetermined vehicle speed due to the deceleration, and the vehicle deceleration is larger than the predetermined deceleration when an attempt is made to set the predetermined gear position for engaging the dog clutch, Setting to a predetermined gear position is prohibited. That is, when the differential rotational speed between the input side and the output side of the dog clutch changes greatly due to the deceleration of the vehicle, it is avoided to try to engage the dog clutch. Therefore, it is possible to suppress or avoid the occurrence of abnormal noise due to the inability to engage the dog clutch. Or it can suppress or avoid that a shock arises or the durability of a dog clutch falls by engaging a dog clutch in the state which the rotation speed is not synchronizing.

It is a flowchart for demonstrating an example of control of the transmission control apparatus in this invention. It is a skeleton figure which shows an example of the transmission control apparatus in this invention. It is an engagement table | surface which shows the engagement apparatus engaged when setting each gear stage. 6 is a time chart for explaining changes in hydraulic pressure or the like when downshifting to the first gear is prohibited during coasting.

  An example of a stepped automatic transmission (shift control device) having a dog clutch according to the present invention is schematically shown in FIG. The vehicle shift control device 1 shown in FIG. 2 is a stepped shift control device that can set the first forward speed to the eighth forward speed, the first reverse speed, and the second reverse speed. The two planetary gear mechanisms 2 and 3 are provided. The configuration will be briefly described. First, a double pinion type planetary gear mechanism (hereinafter referred to as a first planetary gear mechanism) 2 is provided on the engine 4 side which is a power source of the vehicle. The input shaft 15 of the first carrier 5 in the first planetary gear mechanism 2 is connected to the output shaft 6 of the engine 4 via a torque converter (not shown), and the first sun gear 7 is connected to a fixed portion 8 such as a housing. Has been.

  A Ravigneaux type planetary gear mechanism (hereinafter referred to as a second planetary gear mechanism) 3 is provided on the opposite side of the engine 4 with the first planetary gear mechanism 2 interposed therebetween. The second planetary gear mechanism 3 transmits torque input from the engine 4 or the first planetary gear mechanism 2 to a driving wheel (not shown). The second carrier 9 in the second planetary gear mechanism 3 It is connected to the first carrier 5 via the second clutch C2 so that torque can be transmitted. The second sun gear 10 is connected to the first ring gear 11 in the first planetary gear mechanism 2 via the third clutch C3 so as to be able to transmit torque, and also transmits torque to the first carrier 5 via the fourth clutch C4. Connected as possible. Further, the third sun gear 12 is connected via the first clutch C1 so that torque can be transmitted. And the 2nd ring gear 13 is connected with the driving wheel which is not illustrated so that torque transmission is possible.

  Furthermore, a first brake B1 for stopping the rotation of the second sun gear 10 and a second brake B2 for stopping the rotation of the second carrier 9 are provided. The first brake B1 is a conventionally known friction engagement mechanism, and is configured to control the transmission torque capacity. On the other hand, the second brake B2 corresponds to the dog clutch in the present invention, and although not shown, the dog teeth formed on the fixed portion 8 and the dog teeth formed on the second carrier 9 are meshed. Thus, the rotation of the second carrier 9 is stopped. Briefly explaining the operation when the clutches C1, C2, C3, C4 are engaged or disengaged, a hydraulic actuator is attached to at least one of the input side and the output side of each clutch C1, C2, C3, C4. ing. Accordingly, at the time of engagement, by supplying hydraulic pressure to the hydraulic actuator, one of the input side and the output side of each clutch C1, C2, C3, C4 is engaged when approaching the other. On the other hand, by reducing the hydraulic pressure of the hydraulic actuator, one of the input side and the output side of each of the clutches C1, C2, C3, C4 is released from the other side. Similarly, the engagement or release of each brake B1, B2 is managed by the hydraulic pressure supplied to the hydraulic actuator.

  In this embodiment, an electronic control device (for controlling the engagement or release of each of the clutches C1, C2, C3, C4 and the brakes B1, B2 and for electrically controlling the fuel supply of the engine 4) ( ECU) 14 is provided. The ECU 14 corresponds to the controller in the present invention, and is configured mainly with a microcomputer. The ECU 14 is configured to receive data such as the vehicle speed and the accelerator opening, perform calculations using the input data and data stored in advance, and output the calculation result as a control command signal. Has been.

  FIG. 3 shows an engagement table of the shift control device shown in FIG. Note that “◯” shown in FIG. 3 indicates an engaged state, and “−” indicates a released state. As shown in FIG. 3, the first forward speed is set by engaging the first clutch C1 and the second brake B2, and the second forward speed is determined by engaging the first clutch C1 and the first brake B1. Set by engaging. That is, switching between the first forward speed and the second forward speed is performed by either the first brake B1 or the second brake B2 with the first clutch C1 engaged. This is done by releasing (B2) and engaging the other brake B2 (B1).

  Next, the control when the vehicle configured as described above has a reduced vehicle speed due to coasting will be described with reference to FIG. The control shown in FIG. 1 is executed by an ECU 14 corresponding to the controller of the present invention. In the following description, the second brake B2 is referred to as a dog clutch B2.

  First, it is determined in step S1 whether or not the traveling vehicle requires a downshift (coast down) due to coasting. This step S1 is determined based on the vehicle speed or the like, as is conventionally known. If the vehicle speed is higher than a predetermined vehicle speed and it is not necessary to perform coast down, and the determination is negative in step S1, this control is temporarily terminated.

  On the other hand, when it is determined that the vehicle speed is equal to or lower than the predetermined vehicle speed and it is necessary to perform a downshift, and when the determination is affirmative in step S1, the process proceeds to step S2. In step S2, it is determined whether or not the downshift is a downshift from the second speed to the first speed (2 → 1 shift). If the determination is negative in step S2 because it is not a downshift from the second speed to the first speed, this control is temporarily terminated. In this embodiment, it is determined whether or not the shift is from the second speed to the first speed. However, the present invention is not limited to this configuration. It may be configured to determine that the gear shift is to.

  If the determination in step S2 is affirmative due to the downshift from the second speed to the first speed, the process proceeds to step S3. In step S3, the vehicle deceleration due to coasting and the hydraulic pressure (brake master pressure) in the brake master cylinder are estimated or measured. In step S3, the present invention is not limited to estimating or measuring the vehicle deceleration or the brake master pressure, but may be any configuration that confirms a parameter that allows the vehicle deceleration to be known. Further, the deceleration, the brake master pressure, and the like may be calculated and obtained. After estimating or measuring the deceleration of the vehicle by the above means, the process proceeds to step S4.

  In step S4, it is determined whether or not the deceleration estimated or measured in step S3 is greater than a predetermined deceleration. This predetermined deceleration is determined by whether or not the rotation speed of the dog clutch B2 can be synchronized, and is possible when the vehicle deceleration is equal to or lower than the predetermined deceleration. If it is determined, the process proceeds to step S5.

  In step S5, a shift from the second speed to the first speed is executed. Specifically, by reducing the hydraulic pressure of the first clutch C1, slip (slip) occurs from the state where the first clutch C1 is completely engaged. Therefore, the differential rotation speed between the input side and the output side in the dog clutch B2 can be gradually reduced. Accordingly, the dog clutch B2 can be engaged with the rotation speed of the dog clutch B2, and a shock at the time of engagement can be suppressed. After the dog clutch B2 is engaged, it is completely engaged by increasing the hydraulic pressure of the first clutch C1, and once the setting of the first gear is completed, this control is once ended.

  On the other hand, if it is determined that it is difficult to synchronize the rotation speed of the dog clutch B2 even if the first clutch C1 is slipped because the vehicle deceleration is larger than the predetermined deceleration, that is, in step S4. If a positive determination is made, the process proceeds to step S6. In step S6, the engagement (fastening) of the first clutch C1 and the first brake B1 is maintained, and the engagement of the dog clutch B2 is prohibited (stopped). That is, when the deceleration is large, shifting to the first speed is prohibited, and traveling at the second speed is maintained.

  After the shift to the first speed is prohibited, the process proceeds to step S7, and it is determined whether or not the vehicle has been stopped by a vehicle speed sensor (not shown). If a negative determination is made in step S7 because the vehicle has not stopped, the process proceeds to step S8. In step S8, it is determined whether or not the vehicle has re-accelerated due to the driver's accelerator operation or the like. If a negative determination is made in step S8 because the vehicle is not reaccelerated and is decelerating, the determination in step S7 is executed again. On the other hand, if the vehicle is reaccelerated and the determination is affirmative in step S8, the vehicle is accelerated with the second gear set, and this control is temporarily terminated.

  Further, when the vehicle is stopped and the determination is affirmative in step S7, the process proceeds to step S9. In step S9, after an instruction is given to engage dog clutch B2, an instruction is issued to release first brake B1 after a predetermined time has elapsed. That is, after the vehicle is stopped, the first clutch is set by engaging the dog clutch B2 and then releasing the first brake B1.

  Next, changes in hydraulic pressure and the like acting on the first clutch C1, the first brake B1, and the dog clutch (second brake) B2 when the above control is executed will be described with reference to the time chart of FIG. In the following description, the brake is operated by the driver and the vehicle is decelerating rapidly, and the second gear is set as the gear position.

  As shown in FIG. 4, the turbine rotation speed is rapidly decreased due to the rapid deceleration of the vehicle. If the vehicle speed becomes lower than the predetermined vehicle speed as the turbine speed decreases, it is determined that a downshift is necessary as shown in step S2. When it is determined that a downshift is necessary, at the same time, as shown in step S3, the vehicle deceleration, the brake master pressure, and the like are confirmed. Thereafter, as shown in step S4, it is determined whether or not the rotation speed of the dog clutch B2 can be synchronized based on the deceleration and brake master pressure (shift determination & deceleration confirmation).

  If it is determined that it is difficult to synchronize the rotation speed of the dog clutch B2 due to vehicle deceleration or the like, the shift to the first gear is prohibited as shown in step S6. That is, as shown in FIG. 4, since the hydraulic pressure is not supplied to the dog clutch B2, it is maintained in a released state, and the first brake B1 is maintained in an engaged state because the supply of hydraulic pressure is continued. . As described above, since the first clutch C1 is engaged at any of the first gear and the second gear, it is maintained in a state where hydraulic pressure is supplied.

  If it is determined that the vehicle speed further decreases and the vehicle has stopped, an engagement instruction is issued to the dog clutch B2 as shown in step S9, whereby hydraulic pressure is supplied to the dog clutch B2 (stop determination). Accordingly, in the dog clutch B2, the input side and the output side, that is, the dog teeth of the second carrier 9 and the dog teeth of the fixing portion 8 are engaged.

  Further, when it is determined that the vehicle has stopped, the hydraulic pressure of the first brake B1 is reduced after a predetermined time has elapsed. At this time, since the vehicle is stopped, it is difficult to determine whether or not the dog clutch B2 is engaged based on the turbine speed. Therefore, a certain time is estimated from the time when the instruction to reduce the hydraulic pressure of the first brake B1 to the timing when the dog clutch B2 is predicted to be engaged, and after the certain time has elapsed, the first brake B1 Start to reduce the hydraulic pressure. That is, the hydraulic pressure is supplied to the dog clutch B2, and the hydraulic pressure of the first brake B1 starts to be reduced from the timing when it is predicted that the dog clutch B2 is engaged. At this time, a state where both the first brake B1 and the dog clutch B2 are engaged, a so-called tie-up state may occur. Even when the tie-up state occurs, the output torque does not drop because the vehicle is stopped. Therefore, it is possible to suppress the influence on the occupant and to suppress the occurrence of a sense of incongruity to the occupant such as a shock.

  According to this configuration, when the vehicle speed becomes equal to or lower than the predetermined vehicle speed due to deceleration, and the vehicle deceleration is larger than the predetermined deceleration when attempting to set the first speed for engaging the dog clutch B2, Setting to the first gear is prohibited. In other words, when the differential rotational speed between the input side and the output side of the dog clutch B2 changes greatly due to the deceleration of the vehicle, it is avoided to try to engage the dog clutch B2. Therefore, it is possible to suppress or avoid the occurrence of abnormal noise due to the inability to engage the dog clutch B2. Or it can suppress or avoid that a shock arises or the durability of dog clutch B2 falls by engaging dog clutch B2 in the state which the rotation speed is not synchronizing.

  DESCRIPTION OF SYMBOLS 1 ... Transmission control apparatus (stepped automatic transmission), 4 ... Engine, 14 ... Electronic control unit (ECU), B2 ... Dog clutch.

Claims (1)

An engine, a stepped automatic transmission connected to the output side of the engine, and a dog clutch that is engaged to set a predetermined shift speed by the stepped automatic transmission, the vehicle speed is lower than a predetermined vehicle speed In the vehicle shift control device configured to set the predetermined shift speed in a case,
A controller for controlling the stepped automatic transmission;
The controller is
The vehicle is configured to prohibit a downshift to the predetermined gear position when the deceleration of the vehicle when the vehicle speed is equal to or lower than the predetermined vehicle speed is greater than a predetermined deceleration. A vehicle shift control device.

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