Automatic transmission control device

Abstract

A control device for an automatic transmission that can quickly reduce variations in the friction coefficient of a clutch mechanism. [Solution] A control device for an automatic transmission having a first torque transmission path and a second torque transmission path that transmit torque from a vehicle's driving force source to the driving wheels, and in which a first engagement mechanism and a second engagement mechanism that can selectively block the transmission of torque in the second torque transmission path are arranged in series, wherein the first engagement mechanism has a synchromesh mechanism and transmits torque from the driving force source to the driving wheels via the first torque transmission path, while the second engagement mechanism is in a disengaged state, and when the vehicle speed is within a predetermined range of a specified vehicle speed (Yes in step S1), the first engagement mechanism is repeatedly switched between the disengaged state and the engaged state (step S2).

Description

[Technical Field]

[0001] The present invention relates to a control device for an automatic transmission equipped with an engagement mechanism that can selectively interrupt the transmission of torque between a drive power source and drive wheels. [Background technology]

[0002] Patent Document 1 describes a control device for an automatic transmission including a first input shaft and a second input shaft to which engine torque is transmitted, a first friction clutch mechanism that selectively engages the first input shaft with a first auxiliary input shaft connected to a gear for establishing a predetermined gear, and a second friction clutch mechanism that selectively engages the second input shaft with a second auxiliary input shaft connected to a gear for establishing another gear. The control device transmits torque from the engine to drive wheels by engaging either the first clutch mechanism or the second clutch mechanism. The control device is configured to perform gear changes by transitioning one clutch mechanism from an engaged state to an engaged state while transitioning the other clutch mechanism from a disengaged state. Because the clutch mechanisms have variations in friction coefficients at an initial stage, the control device is configured to set the engagement pressures of the disengagement clutch mechanism and the on-coming clutch mechanism during the inertia phase of a gear shift transition higher than those during normal gear shift control until the lifetime heat absorbed by the clutch mechanisms reaches a predetermined heat value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-166603 Summary of the Invention [Problem to be solved by the invention]

[0004] The automatic transmission control device described in Patent Document 1 increases the engagement pressure between the on-coming clutch mechanism and the off-coming clutch mechanism more than during normal shift control during gear shift control until the lifetime heat absorbed by the clutch mechanism reaches a predetermined heat amount. The lifetime heat absorbed by the clutch mechanism increases with gear shifting. In other words, with the automatic transmission control device described in Patent Document 1, the variation in the friction coefficient of the clutch mechanism depends on the number of gear shifts, and it may take time for the variation in the friction coefficient of the clutch mechanism to be reduced after the vehicle is shipped, or the number of gear shifts may increase while the friction coefficient of the clutch mechanism is still varying.

[0005] The present invention has been made in light of the above technical problems, and aims to provide a control device for an automatic transmission that can quickly reduce variations in the friction coefficient of the clutch mechanism. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention provides a control device for an automatic transmission having a first torque transmission path and a second torque transmission path that transmit torque from a vehicle's driving force source to the driving wheels, and in which a first engagement mechanism and a second engagement mechanism that can selectively block the transmission of torque in the second torque transmission path are arranged in series, wherein the first engagement mechanism has an input side rotating member, an output side rotating member, a sleeve that engages with one of the input side rotating member and the output side rotating member and moves toward the other rotating member to engage with it, thereby connecting the input side rotating member and the output side rotating member, and a synchronizer ring that frictionally contacts the other of the input side rotating member and the output side rotating member by pressing the sleeve toward the other rotating member, and is characterized in that it transmits torque from the driving force source to the driving wheels via the first torque transmission path, and repeatedly switches the first engagement mechanism between the engaged state and the disengaged state when the second engagement mechanism is in a disengaged state and the vehicle speed is within a predetermined range of a specified vehicle speed. [Effects of the Invention]

[0007] According to this invention, a vehicle includes a first torque transmission path and a second torque transmission path that transmit torque from a driving force source to driving wheels, and a first engagement mechanism and a second engagement mechanism that can selectively interrupt torque transmission in the second torque transmission path are arranged in series. That is, by disengaging at least one of the first engagement mechanism and the second engagement mechanism, torque transmission via the second torque transmission path can be interrupted. The first engagement mechanism is configured as an engagement mechanism with a so-called synchromesh mechanism. Torque is transmitted from the driving force source to the driving wheels via the first torque transmission path, and the first engagement mechanism is repeatedly switched between a released state and an engaged state when the second engagement mechanism is in a released state and the vehicle speed is within a predetermined vehicle speed range. That is, the first engagement mechanism is switched between a released state and an engaged state while torque transmission via the second torque transmission path is interrupted. In other words, the first engagement mechanism is switched between a released state and an engaged state without being involved in torque transmission from the driving force source to the driving wheels.

[0008] Therefore, the friction coefficient of the synchronizer ring that constitutes the first engagement mechanism can be stabilized without depending on the number of times the first engagement mechanism is engaged in order to transmit torque from the driving force source to the drive wheels via the second torque transmission path. This makes it possible to shorten the time it takes for the variation in the friction coefficient of the first clutch mechanism to be reduced after the vehicle is shipped, and to reduce the number of times the first clutch mechanism is engaged in order to set the second torque transmission path when the friction coefficient of the first clutch mechanism varies. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram schematically illustrating an example of a vehicle according to an embodiment of the present invention. [Figure 2]1A and 1B are diagrams for explaining an example of a dog clutch having a synchromesh mechanism, in which (a) shows the state in which the dog clutch is released, (b) shows the process of synchronizing the input side rotating member and the output side rotating member, and (c) shows the state in which the dog clutch is engaged. [Figure 3] 3 is a flowchart illustrating an example of control executed by a control device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described based on the embodiments shown in the drawings. Note that the embodiments described below are merely examples of specific embodiments of the present invention, and are not intended to limit the present invention.

[0011] Fig. 1 shows a schematic diagram of an example of a vehicle according to an embodiment of the present invention. The vehicle Ve shown in Fig. 1 is equipped with an engine (ENG) 1 as a driving force source. The engine 1 can be configured in the same manner as various engines such as conventional gasoline engines and diesel engines, and is configured to output torque by combusting a mixture of supplied air and fuel.

[0012] A torque converter (T / C) 3 is connected to the output shaft 2 of the engine 1. This torque converter 3 can be configured similarly to torque converters provided in conventional vehicles equipped with an engine as a driving force source, and is made up of a pump impeller (not shown) connected to the output shaft 2 of the engine 1, a turbine runner (not shown) disposed opposite the pump impeller and connected to an output shaft 4, and a stator that rectifies the flow discharged from the turbine runner. The torque converter 3 may be equipped with a lock-up clutch for connecting the pump impeller and the turbine runner.

[0013] A belt-type continuously variable transmission 5 is connected to the output shaft 4 of the torque converter 3. This belt-type continuously variable transmission 5 is composed of a primary pulley 6 connected to the output shaft 4 of the torque converter 3, a secondary pulley 8 connected to an output shaft 7 of the belt-type continuously variable transmission 5, and a belt 9 wound around the primary pulley 6 and the secondary pulley 8. The winding radius of the belt 9 is changed by changing the pulley width of the primary pulley 6 and the pulley width of the secondary pulley 8 using a hydraulic actuator (not shown) or the like, thereby continuously changing the gear ratio. The maximum gear ratio that can be set by the belt-type continuously variable transmission 5 is set to be smaller than the gear ratio of a reduction gear pair, which will be described later.

[0014] Drive wheels 11 are connected to the output shaft 7 of the belt-type continuously variable transmission 5 via a first clutch mechanism C1 and a transmission output shaft (hereinafter referred to as the TM output shaft) 10. The first clutch mechanism C1 only needs to be able to selectively interrupt the torque transmission path between the belt-type continuously variable transmission 5 and the drive wheels 11, and can be configured by a friction clutch mechanism or a meshing clutch mechanism.

[0015] By engaging the first clutch mechanism C1 described above, torque can be transmitted from the engine 1 to the drive wheels 11, and this torque transmission path corresponds to the "first torque transmission path" in the embodiment of the present invention. By connecting the engine 1 and the drive wheels 11 via the belt-type continuously variable transmission 5 in this manner, the gear ratio between the engine 1 and the drive wheels 11 can be continuously changed.

[0016] Furthermore, a forward / reverse switching mechanism 12 is further connected to the output shaft 4 of the torque converter 3. This forward / reverse switching mechanism 12 can be configured, for example, by a single-pinion planetary gear mechanism, a forward clutch mechanism, and a reverse brake mechanism. Specifically, the forward / reverse switching mechanism 12 can be configured by connecting the output shaft 4 of the torque converter 3 to the sun gear of the planetary gear mechanism, connecting the output shaft 13 to the ring gear, providing a forward clutch mechanism so that any two of the rotating elements can be connected, and connecting a reverse brake mechanism to the carrier.

[0017] In the forward / reverse switching mechanism 12 configured as described above, the output shaft 4 of the torque converter 3 and the output shaft 13 of the forward / reverse switching mechanism 12 rotate integrally by engaging the forward clutch mechanism, and the rotation of the output shaft 4 of the torque converter 3 is reversed and torque is increased and transmitted to the output shaft 13 by engaging the reverse brake mechanism. Furthermore, by disengaging the forward clutch mechanism and the reverse brake mechanism, the transmission of torque between the output shaft 4 of the torque converter 3 and the output shaft 13 of the forward / reverse switching mechanism 12 can be interrupted. In other words, the forward clutch mechanism and the reverse brake mechanism can function as a starting clutch C2 that selectively interrupts the transmission of torque via the forward / reverse switching mechanism 12. In FIG. 1, this is shown as the starting clutch C2, and this starting clutch C2 corresponds to the "second engagement mechanism" in this embodiment of the present invention.

[0018] A reduction gear pair 14 that forms a gear ratio of the first forward speed is connected to the output shaft 13 of the forward / reverse switching mechanism 12. That is, the reduction gear pair 14 is composed of a drive gear 15 connected to the output shaft 13 and a driven gear 16 that meshes with the drive gear 15 and has a larger diameter than the drive gear 15.

[0019] The output shaft 17 connected to the driven gear 16 is connected to the TM output shaft 10 via a mesh-type clutch mechanism (hereinafter simply referred to as a dog clutch) C3, which corresponds to the "first engagement mechanism" in this embodiment of the present invention. Therefore, by engaging the starting clutch C2 and the dog clutch C3, the engine 1 and the driving wheels 11 are connected to each other so that torque can be transmitted via the reduction gear pair 14. In other words, by disengaging either the starting clutch C2 or the dog clutch C3, the transmission of torque between the engine 1 and the driving wheels 11 via the reduction gear pair 14 can be cut off. This torque transmission path via the reduction gear pair 14 corresponds to the "second torque transmission path" in this embodiment of the present invention.

[0020] The vehicle Ve described above is also provided with a controller (ECU) 18 for switching the clutch mechanisms C1, C2, and C3 between an engaged state and a released state, and for controlling the gear ratio of the belt-type continuously variable transmission 5. This controller 18 is configured mainly to include a microcomputer, similar to controllers provided in conventional vehicles, and is configured to receive signals from various sensors, such as a rotation speed sensor 19 that detects the rotation speed of the TM output shaft 10 and an accelerator opening sensor 20 that detects the amount of operation of the accelerator device by the driver, and to output command signals to the clutch mechanisms C1, C2, and C3 and the belt-type continuously variable transmission 5 based on the input signals and pre-stored arithmetic expressions, maps, and the like.

[0021] When the vehicle Ve configured as described above starts, the dog clutch C3 is engaged, and the transmission torque capacity of the starting clutch C2 is gradually increased to engage the starting clutch C2. As the vehicle speed increases, the starting clutch C2 is released and the first clutch mechanism C1 is engaged, thereby changing the torque transmission path from the engine 1 to the drive wheels 11 to a torque transmission path via the belt-type continuously variable transmission 5. When the vehicle speed while traveling with the first clutch mechanism C1 engaged reaches or exceeds a predetermined first predetermined vehicle speed, the dog clutch C3 is released.

[0022] On the other hand, when torque is transmitted via the belt-type continuously variable transmission 5, in order to improve response when it becomes necessary to change to a gear ratio equivalent to the first forward gear due to sudden deceleration, etc., the dog clutch C3 is configured to be engaged when the vehicle speed falls to or below a predetermined second specified vehicle speed that is slower than the first specified vehicle speed.

[0023] In addition, the vehicle Ve described above is configured to be able to set a manual shift mode that sets the gear ratio according to the driver's shift operation, and a sports mode that increases the vehicle's response to accelerator and brake operations, and when such a manual shift mode or sports mode is set, the dog clutch C3 is configured to be engaged when the vehicle speed drops below a third predetermined vehicle speed that is higher than the first and second predetermined vehicle speeds.

[0024] After the starting clutch C2 and the dog clutch C3 are released, the rotation speed of the output shaft 17 gradually decreases due to sliding resistance, etc., so that the rotation speed of the input side is extremely slow or stopped when the dog clutch C3 is re-engaged.

[0025] As described above, when the dog clutch C3 is re-engaged, the rotation speed on the input side is extremely low or stopped, whereas the rotation speed on the output side is the same as the rotation speed of the TM output shaft 10 and is relatively high. Therefore, the dog clutch C3 is provided with a synchromesh mechanism 21 for gradually reducing the difference between the rotation speed on the input side and the rotation speed on the output side. Figure 2 shows a diagram for explaining the configuration of the dog clutch C3 having the synchromesh mechanism 21. Note that a cross-sectional view is shown on the left side of Figure 2, and a view from above of the left-hand view is shown on the right side.

[0026] The dog clutch C3 shown in FIG. 2 is provided with an input gear (not shown) and an output gear 22 that face each other in the direction of the rotation center axis. The input gear is connected to the output shaft 17, and the output gear 22 is connected to the TM output shaft 10. The input gear and the output gear 22 have the same outer diameter, and teeth 22a with tooth traces parallel to the direction of the rotation center axis are formed on their outer circumferential surfaces. The tip surface of the teeth 22a on the input gear side forms a tapered chamfered surface. The number of teeth of the input gear and the number of teeth of the output gear 22 are formed to be the same. The input gear corresponds to the "input side rotating member" in embodiments of the present invention, and the output gear 22 corresponds to the "output side rotating member" in embodiments of the present invention.

[0027] A cylindrical sleeve 23 meshes with the input gear. That is, internal teeth 23a that mesh with the teeth of the input gear are formed on the inner surface of the sleeve 23. An annular groove 23b into which a shift fork (not shown) fits is formed on the outer circumferential surface of the sleeve 23, and the sleeve 23 is configured to move in the direction of the rotation center axis by moving the shift fork with an actuator. The tip end surface of the internal teeth 23a of the sleeve 23a on the output gear 22 side is a tapered chamfered surface.

[0028] The teeth of the input gear and the internal teeth 23a of the sleeve 23 are partially missing at predetermined intervals in the circumferential direction, and a shifting key 24 is fitted into these missing parts. A protrusion 24a that protrudes toward the sleeve 23 is provided on the outer surface of this shifting key 24, and a recess 23c that engages with the protrusion 24a in the axial direction is formed on the inner surface of the sleeve 23. The shifting key 24 is pressed against the inner surface of the sleeve 23 by a spring (not shown).

[0029] The protrusion 24a and recess 23c are formed with inclined ends in the axial direction of the sleeve 23. Therefore, when the sleeve 23 is moved in the axial direction by the shift fork, the inclined surfaces of the recess 23c and the protrusion 24a come into contact with each other, and the sleeve 23 and the shifting key 24 move together in the axial direction. When the end face of the shifting key 24 comes into contact with a synchronizer ring 25 (described later) and its axial movement is restricted, the normal component of the load acting on the inclined surface compresses the spring, causing the protrusion 24a of the shifting key 24 to fall out of the recess 23c of the sleeve 23 as shown in FIG. 3(b), and the sleeve 23 and the shifting key 24 move relative to each other.

[0030] The output gear 22 is formed with a cylindrical cone portion 22b that protrudes from the inside of the output gear 22 toward the input gear side. The outer circumferential surface of this cone portion 22b is formed into a tapered surface whose outer diameter gradually decreases toward the tip on the input gear side.

[0031] A synchronizer ring 25 is fitted onto the cone portion 22b. The synchronizer ring 25 is formed in an annular shape, with its outer diameter being the same as that of the output gear 22, and its outer peripheral surface is formed with teeth 25a having the same number of teeth as the output gear 22. The tip surface of the teeth 25a on the input gear side is a tapered chamfered surface. The outer peripheral surface of the synchronizer ring 25 is formed with a fitting portion 25b into which the tip of the shifting key 24 fits, and the inner peripheral surface of the synchronizer ring 25 is formed into a tapered surface whose inner diameter gradually increases toward the output gear 22 side so as to abut against the cone portion 22b of the output gear 22.

[0032] This tapered surface is configured to be in frictional contact with the cone portion 22b, and therefore a friction material (not shown) is attached to the tapered surface. This friction material is made by solidifying carbon fiber with a resin material, and is fixed to the base material of the synchronizer ring 25 with an adhesive.

[0033] In the dog clutch C3 configured as described above, when the sleeve 23 begins to move due to operation of the shift fork, the shifting key 24 moves as shown in FIG. 3(a), and the shifting key 24 presses the synchronizer ring 25 toward the output gear 22. The tapered surface of the synchronizer ring 25 is then pressed against the cone portion 22b of the output gear 22. Therefore, a frictional force corresponding to the pressing force and the friction coefficient between the tapered surface and the cone portion 22b acts in a direction that reduces the rotational speed difference between the input gear and the output gear 22.

[0034] When the sleeve 23 is further moved, as shown on the right side of FIG. 3(b), the chamfered surfaces of the internal teeth 23a of the sleeve 23 press against the chamfered surfaces of the teeth 25a of the synchronizer ring 25. As a result, as shown on the left side of FIG. 3(b), the tapered surface of the synchronizer ring 25 is pressed even more strongly against the cone portion 22b of the output gear 22. In other words, the frictional force increases further, reducing the difference in rotation speed between the input gear and the output gear 22. In addition, the chamfered surfaces of the internal teeth 23a of the sleeve 23 press against the chamfered surfaces of the teeth 22a of the output gear 22, causing the synchronizer ring 25 to rotate.

[0035] Therefore, by further moving the sleeve 23, the internal teeth 23a of the sleeve 23 pass between the teeth 25a of the synchronizer ring 25, and the internal teeth 23a of the sleeve 23 mesh with the teeth 22a of the output gear 22, as shown on the right side of Figure 3(c).

[0036] As described above, the synchronizer ring 25 and the output gear 22 are configured to be in frictional contact with each other to reduce the difference in rotation speed between the input gear and the output gear 22, so it is preferable that the friction coefficient of the friction surface is large. However, when the synchronizer ring 25 and the output gear 22 are in frictional contact with each other, the internal teeth 23a of the sleeve 23 mesh with the teeth 22a of the output gear 22 by rotating the synchronizer ring 25. Therefore, if the friction coefficient of the friction surface is too large and the synchronizer ring 25 does not rotate, the sleeve 23 cannot move toward the output gear 22. In this way, the synchromesh mechanism 21 exhibits its performance depending on the friction force (friction coefficient) of the friction surface. Therefore, if the friction coefficient of the friction surface is unstable, the dog clutch C3 may not be able to be smoothly engaged.

[0037] Therefore, the automatic transmission control device according to the embodiment of the present invention is configured to repeatedly switch the dog clutch C3 between the engaged and disengaged states while the vehicle Ve is running, regardless of whether the dog clutch C3 is engaged or disengaged, thereby acclimatizing the friction surface (the outermost surface of the friction material) to a stable state. An example of this control is shown in a flowchart in Figure 3.

[0038] The control example shown in FIG. 3 is executed when the driver selects the drive range, the normal mode is selected (not the manual shift mode or the sport mode), and the break-in control stop flag (described later) is off. In the control example shown in FIG. 3, first, it is determined whether the vehicle speed is within a predetermined vehicle speed range and the vehicle is running steadily with a constant required driving force (step S1). The predetermined vehicle speed range in step S1 can be set, for example, between the second predetermined vehicle speed and the third predetermined vehicle speed. That is, it can be set to a vehicle speed range that does not require engagement of the dog clutch C3 when running in the normal mode, and that is equal to or less than the maximum vehicle speed at which the dog clutch C3 can be engaged. Whether the required driving force is constant can be determined based on the amount of operation of the accelerator device, etc.

[0039] When the vehicle speed is not within a predetermined range, the dog clutch C3 is in an engaged state, or the vehicle speed is such that the dog clutch C3 is not engaged, so the dog clutch C3 cannot be switched to a released state, or engaging the dog clutch C3 may result in a decrease in durability. Also, when the vehicle is not traveling at a steady speed, the dog clutch C3 may be engaged or released as the vehicle speed changes, so it is preferable to maintain the state of the dog clutch C3 in order to prevent a decrease in response when the state of the dog clutch C3 is switched.

[0040] Therefore, if the answer to step S1 is negative, the process returns to step S1. That is, step S1 is repeatedly executed until the condition of step S1 is satisfied. Conversely, if the answer to step S1 is positive because the vehicle speed is within a predetermined vehicle speed range and the vehicle is traveling steadily, the break-in control is executed (step S2). Specifically, the dog clutch C3, which is currently released, is engaged, and then the dog clutch C3 is released.

[0041] Next, the synchronous heat generation amount (heat input amount of the friction material) resulting from executing step S2 is calculated and added to the cumulative heat generation amount stored in controller 18 (step S3). This synchronous heat generation amount in step S3 can be calculated based on the difference in rotation speed between the input gear and output gear 22 at the time when engagement of dog clutch C3 begins, the load for moving sleeve 23 in the axial direction, the time from when engagement of dog clutch C3 begins to when engagement is completed, etc. Furthermore, the cumulative heat generation amount may be calculated by including the synchronous heat generation amount during the inspection process from when dog clutch C3 is mounted on vehicle Ve until shipment, or it may be calculated by accumulating only the synchronous heat generation amount from the time of shipment.

[0042] Then, it is determined whether the cumulative heat generation amount to which the synchronous heat generation amount has been added in step S3 is equal to or greater than a predetermined amount (step S4). This step S4 is a step for determining whether heat has been input to the friction material to an extent that the friction coefficient of the friction material becomes stable. Therefore, the heat input amount at which the friction coefficient of the friction material becomes stable can be determined in advance by experiment or simulation, and this heat input amount can be set as the predetermined amount in step S4.

[0043] If the cumulative heat generation amount is equal to or greater than the predetermined amount and the answer is affirmative in step S4, the break-in control stop flag, which indicates that the friction coefficient of the friction material has stabilized, is switched on (step S5), and this routine is temporarily terminated. Conversely, if the cumulative heat generation amount is less than the predetermined amount and the answer is negative in step S4, it is considered that the friction coefficient of the friction material has not yet stabilized. Therefore, if the answer is negative in step S4, the routine is temporarily terminated after a predetermined interval (step S6).

[0044] As described above, the vehicle includes a path for transmitting torque from the engine 1 to the drive wheels 11 via the belt-type continuously variable transmission 5 and a path for transmitting torque via the forward / reverse switching mechanism 12 and the reduction gear pair 14. The starting clutch C2 and the dog clutch C3 are disposed in series in the path for transmitting torque via the forward / reverse switching mechanism 12 and the reduction gear pair 14. Therefore, by disengaging at least one of the starting clutch C2 and the dog clutch C3, transmission of torque via the transmission path can be interrupted. When the driver selects the drive range, the normal mode is set, and the vehicle speed is within a predetermined vehicle speed range, i.e., when torque is being transmitted via the belt-type continuously variable transmission 5, the dog clutch C3 is repeatedly switched between a released state and an engaged state. That is, the dog clutch C3 is switched between a released state and an engaged state while transmission of torque via the forward / reverse switching mechanism 12 and the reduction gear pair 14 is interrupted. In other words, the dog clutch C3 is switched between the released state and the engaged state without being involved in the transmission of torque from the engine 1 to the drive wheels 11.

[0045] Therefore, the friction coefficient of the synchronizer ring 25 constituting the dog clutch C3 can be stabilized regardless of the number of times the dog clutch C3 is engaged in order to transmit torque from the engine 1 to the drive wheels 11 via the forward / reverse switching mechanism 12 and the reduction gear pair 14. This makes it possible to shorten the time it takes for the variation in the friction coefficient of the dog clutch C3 to be reduced from the time of shipment of the vehicle Ve, and to reduce the number of times the dog clutch C3 is engaged in order to set a path for transmitting torque via the forward / reverse switching mechanism 12 and the reduction gear pair 14 when the friction coefficient of the dog clutch C3 varies. Furthermore, because the friction coefficient of the synchronizer ring 25 can be stabilized while the vehicle is running as described above, the number of steps in the manufacturing process and pre-shipment testing process leading up to shipment of the vehicle Ve can be reduced.

[0046] In addition, the vehicle in this embodiment of the present invention is required to have at least two torque transmission paths, one of which is equipped with a dog clutch, and is not limited to vehicles equipped with a belt-type continuously variable transmission, but may have various configurations, such as a stepped transmission mechanism. [Explanation of symbols]

[0047] 1 engine 2,4,7,10,13,17 Output shaft 5 Belt-type continuously variable transmission 11 Drive wheels 12 Forward / reverse switching mechanism 14 Reduction gear pair 18 Controller 21 Synchromesh mechanism 22 Output gear 22a,25a Teeth 22b Cone section 23 Sleeve 23a Internal teeth 23b Groove 23c Recess 24 Shifting Key 24a Protrusion 25 Synchronizer ring 25b Mating part C1 clutch mechanism C2 Starting clutch C3 Dog Clutch Vehicle

Claims

1. A control device for an automatic transmission including a first torque transmission path and a second torque transmission path that transmit torque from a driving force source of a vehicle to a driving wheel, and a first engagement mechanism and a second engagement mechanism that can selectively interrupt transmission of torque in the second torque transmission path, arranged in series, the first engagement mechanism includes an input side rotating member, an output side rotating member, a sleeve that meshes with one of the input side rotating member and the output side rotating member and moves toward the other rotating member to mesh with it, thereby connecting the input side rotating member and the output side rotating member, and a synchronizer ring that frictionally contacts the other of the input side rotating member and the output side rotating member by pressing the sleeve toward the other rotating member, Torque is transmitted from the driving force source to the drive wheels via the first torque transmission path, and the second engagement mechanism is in a disengaged state, and when the vehicle speed is within a predetermined vehicle speed range, the first engagement mechanism is repeatedly switched between a disengaged state and an engaged state.

1. A control device for an automatic transmission comprising:

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