JP2019049290A - Shift control device - Google Patents

Abstract

To provide a shift control device capable of actualizing a quick gear change.SOLUTION: The shift control device, which is used for a transmission including a hydraulic transmission unit connecting via a closed circuit one variable displacement pump motor and the other to each of which power from a driving source, split in two with a differential mechanism, is input, and a stepped transmission unit having first and second engagement mechanisms capable of outputting the power of the input/output shaft of one variable displacement pump motor and that of the other to an output shaft, respectively, includes a first control unit for energizing the first or second engagement mechanism in the direction of the disengagement in the state that the first and second engagement mechanisms are both put into engagement, and a second control unit for controlling one variable displacement pump motor or the other to reduce its torque passing through the first or second engagement mechanism in the state that the first or second engagement mechanism is energized in the direction of the disengagement.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a transmission control device.

  Conventionally, a hydromechanical continuously variable transmission (hydromechanical transmission: HMT) combining a hydrostatic continuously variable transmission (hydrostatic transmission: HST) and a differential mechanism is known (for example, Patent Document 1) See). Patent Document 1 discloses a so-called "input split type" HMT in which driving force from an engine is divided by a planetary gear mechanism and input to two hydraulic pump motors.

Patent No. 2522219 gazette

  The HMT described in Patent Document 1 switches between a low speed mode in which the driving force output from one hydraulic pump motor is transmitted to the wheels and a high speed mode in which the driving force output from the other hydraulic pump motor is transmitted to the wheels It is possible to configure.

  When switching from the low speed mode to the high speed mode or from the high speed mode to the low speed mode, first, the low speed clutch between one hydraulic pump motor shaft and output shaft, and the high speed clutch between the other hydraulic pump motor shaft and output shaft At the same time. After that, one hydraulic pump motor is controlled to zero the torque passing through the low speed clutch or the high speed clutch, and then the low speed clutch or the high speed clutch is disengaged.

  However, in the HMT described in Patent Document 1, one hydraulic pump motor is controlled to make the torque passing through the low speed clutch or the high speed clutch zero, and then the low speed clutch or the high speed clutch is disengaged. There was a problem that it took time to shift.

  An object of the present invention is to provide a shift control device capable of rapidly performing a shift.

  A shift control device according to the present invention includes: a hydraulic transmission unit in which one and the other variable displacement pump motors, one of which receives power from a drive source divided into two by a differential mechanism, are connected by a closed circuit; A transmission control apparatus for use in a transmission comprising: a geared transmission having first and second engagement mechanisms capable of outputting power of input and output shafts of one and the other variable displacement pump motors to the output shaft. A first control unit configured to bias the first or second engagement mechanism in a direction for disengaging the engagement mechanism when the first and second engagement mechanisms are engaged together; The one or the other variable displacements so as to reduce the torque passing through the first or second engagement mechanism while biasing the first or second engagement mechanism in the disengaging direction A second control unit that controls the die pump motor; Obtain.

  According to the transmission according to the present invention, gear change can be performed promptly.

A skeleton diagram showing an overall configuration of a vehicle according to an embodiment of the present invention A chart showing the relationship between the state of the stepped transmission and the operating state of each sleeve Skeleton diagram showing the first transmission state Skeleton diagram showing the first intermediate transmission state Skeleton diagram showing the second transmission state Skeleton diagram showing the second intermediate transmission state Skeleton diagram showing the third transmission state Diagram showing the relationship between speed ratio and displacement volume A flowchart showing coordinated shift control processing from the first intermediate transmission state to the second transmission state

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiment described below is an example, and the present invention is not limited by this embodiment.

  First, with reference to FIG. 1, an overall configuration of a vehicle 1 equipped with a hydraulic mechanical transmission according to the present embodiment will be described. The longitudinal direction of the vehicle 1 is depicted in FIG. In the following description, the front side of the vehicle may be simply referred to as "front" and the rear side of the vehicle may be simply referred to as "rear".

  The vehicle 1 includes a drive source 10, a damper 20, a differential mechanism 30, a hydraulic transmission unit 40, a stepped transmission unit 50, and a control device 80. A drive wheel 64 is coupled to the output side of the stepped transmission unit 50 via a propeller shaft 61, a differential 62 and a drive shaft 63 so that power can be transmitted.

  The drive source 10 is, for example, a diesel engine. The drive source 10 may be a gasoline engine, an electric motor or the like. The input side member 21 of the damper 20 is connected to the output shaft 11 of the drive source 10. In the following, the drive source 10 will be described as a diesel engine.

  The damper 20 includes an input side member 21, an output side member 22, and an elastic connecting member 23 that elastically connects the input side member 21 and the output side member 22. The output side member 22 of the damper 20 is connected to the input shaft 31 of the differential mechanism 30. The damper 20 has a function of suppressing transmission of rotational vibration generated by the drive source 10 to the differential mechanism 30. The structure of the damper 20 is the same as that of a general damper, and thus the detailed description is omitted.

  The differential mechanism 30 is provided with a plurality of bevel gears 32, a first differential output gear 33 and a second differential output gear 34 provided equidistantly in the circumferential direction. As shown in FIG. 1, the bevel gear 32 is rotatably supported by the input shaft 31 in a relatively rotatable manner. The first differential output gear 33 is provided at the front end of the first input / output shaft 41 a of the first pump motor 41. The second differential output gear 34 is provided at the front end of the differential output shaft 35.

  The differential output shaft 35 is a cylindrical member coaxial with the first input / output shaft 41 a and provided on the outer peripheral side of the first input / output shaft 41 a. A first gear 36 is provided at the rear end of the differential output shaft 35. The differential output shaft 35 is pivotally supported by the first input / output shaft 41 a via a bearing (not shown). The first gear 36 meshes with a second gear 37 provided at the front end of the second input / output shaft 42 a of the second pump motor 42.

  In the present embodiment, the number of teeth of the first differential output gear 33 is the same as the number of teeth of the second differential output gear 34. Further, the number of teeth of the first gear 36 is the same as the number of teeth of the second gear 37. The structure of the differential mechanism 30 is the same as that of a general bevel gear type differential mechanism, and thus the detailed description is omitted.

  The hydraulic transmission unit 40 includes a first pump motor 41, a second pump motor 42, and a closed circuit 43 hydraulically connecting the first pump motor 41 and the second pump motor 42. Since the configuration of the closed circuit 43 is the same as a general HST closed circuit, components (charge pump, charge oil passage, relief oil passage, bypass oil passage, etc.) in the closed circuit 43 are omitted in FIG. doing.

  The first pump motor 41 is a so-called double swing pump motor capable of changing the displacement volume from zero to positive and negative directions. The first input / output shaft 41 a of the first pump motor 41 penetrates the first pump motor 41 from the front to the rear. As such a first pump motor 41, various types such as an axial piston type and a radial piston type can be adopted. The first pump motor 41 corresponds to the “other variable displacement pump motor” in the present invention.

  The second pump motor 42 is a so-called double swing pump motor capable of changing the displacement volume from zero to positive and negative directions. The second input / output shaft 42 a of the second pump motor 42 penetrates the second pump motor 42 from the front to the rear. As such a second pump motor 42, various types such as an axial piston type and a radial piston type can be adopted. The second pump motor 42 corresponds to "one variable displacement pump motor" in the present invention.

  In the present embodiment, the first pump motor 41 and the second pump motor 42 use the same type. Also, the maximum displacement volume of the first pump motor 41 is equal to the maximum displacement volume of the second pump motor 42.

  The stepped transmission unit 50 includes a first input / output shaft 41a, a second input / output shaft 42a disposed parallel to the first input / output shaft 41a, a sub shaft 51, and an output shaft 52. The first input / output shaft 41 a corresponds to the “input / output shaft of the other variable displacement pump motor” in the present invention. The second input / output shaft 42a corresponds to "the input / output shaft of one variable displacement pump motor" of the present invention.

  As described above, the first differential output gear 33 of the differential mechanism 30 is provided at the front end of the first input / output shaft 41a. In addition, a first input hub 41b is provided at the rear end of the first input / output shaft 41a so as to rotate integrally with the first input / output shaft 41a.

  The countershaft 51 is a cylindrical member coaxial with the first input / output shaft 41a and provided on the outer peripheral side of the first input / output shaft 41a. A first auxiliary gear 53 is provided at the front end of the auxiliary shaft 51, and a second auxiliary gear 54 is provided at the rear end of the auxiliary shaft 51.

  The first input gear 55 is provided on the outer peripheral side of the first input / output shaft 41a so as to be rotatable relative to the first input / output shaft 41a. The first input gear 55 is provided between the countershaft 51 and the first input hub 41b.

  As described above, the second gear 37 of the differential mechanism 30 is provided at the front end of the second input / output shaft 42a. In addition, a second input hub 42b is provided at the rear end of the second input / output shaft 42a so as to rotate integrally with the second input / output shaft 42a.

  The second input gear 56 is provided to rotate integrally with the second input / output shaft 42a. The second input gear 56 is provided between the second pump motor 42 and the second input hub 42 b. The second input gear 56 meshes with the first auxiliary gear 53.

  An output hub 57 is provided at the front end of the output shaft 52 so as to rotate integrally with the output shaft 52. The first output gear 58 is provided on the outer peripheral side of the output shaft 52 so as to be rotatable relative to the output shaft 52. The first output gear 58 is provided on the rear side of the output hub 57. The first output gear 58 meshes with the second auxiliary gear 54.

  The second output gear 59 is provided to rotate integrally with the output shaft 52. The second output gear 59 is provided on the rear side of the first output gear 58. The second output gear 59 is in mesh with the first input gear 55.

  The stepped transmission portion 50 is provided with a first connection mechanism 71 that selectively and integrally connects the first input / output shaft 41 a and the first input gear 55. The first connection mechanism 71 includes a first input hub 41 b, a first clutch gear 55 a integrally provided with the first input gear 55, and a first sleeve 72.

  The first sleeve 72 is provided on the outer peripheral side of the first input hub 41 b so as to be integrally rotatable with the first input hub 41 b and to be relatively movable in the axial direction. When the first sleeve 72 is in the rear position shown in FIG. 1, the first input / output shaft 41 a and the first input gear 55 can rotate relative to each other.

  By setting the first sleeve 72 to the front position, the first input gear 55 rotates integrally with the first input / output shaft 41 a. In this embodiment, a general synchronizer system is used as the first connection mechanism 71. Since a synchronizer type connection mechanism is known, the detailed description is omitted. The first connection mechanism 71 corresponds to the "second engagement mechanism" in the present invention.

  The geared transmission unit 50 is provided with a second connection mechanism 73 for selectively and integrally rotatably connecting the second input / output shaft 42a and the output shaft 52, or the first output gear 58 and the output shaft 52. ing. The second connection mechanism 73 includes a second input hub 42 b, an output hub 57, an output clutch gear 58 a integrally provided with the first output gear 58, and a second sleeve 74.

  The second sleeve 74 is provided on the outer peripheral side of the output hub 57 so as to be integrally rotatable with the output hub 57 and relatively movable in the axial direction. When the second sleeve 74 is at the center position shown in FIG. 1, the second input / output shaft 42a and the output shaft 52 can be rotated relative to each other. When the second sleeve 74 is at the center position shown in FIG. 1, the first output gear 58 and the output shaft 52 can rotate relative to each other.

  By setting the second sleeve 74 to the front position, the output shaft 52 rotates integrally with the second input / output shaft 42a. Further, by setting the second sleeve 74 to the rear position, the output shaft 52 rotates integrally with the first output gear 58. The second connection mechanism 73 corresponds to the "first engagement mechanism" in the present invention.

  Next, with reference to FIG. 2, the operation of the stepped transmission unit 50 will be described. FIG. 2 is a chart showing the relationship between the state of the stepped transmission unit 50 and the operating states of the sleeves 72 and 74. As shown in FIG.

  The state in which the first sleeve 72 is in the rear position and the second sleeve 74 is in the rear position is referred to as a "first transmission state" (see FIG. 3). In the first transmission state, the power from the drive source 10 is output from the second input / output shaft 42a via the second input gear 56, the first auxiliary gear 53, the second auxiliary gear 54, and the first output gear 58. It is transmitted to the shaft 52.

  A state in which the first sleeve 72 is in the front position and the second sleeve 74 is in the center position is referred to as a "second transmission state" (see FIG. 5). In the second transmission state, the power from the drive source 10 is transmitted from the first input / output shaft 41 a to the output shaft 52 via the first input gear 55 and the second output gear 59.

  A state in which the first sleeve 72 is in the rear position and the second sleeve 74 is in the front position is referred to as a "third transmission state" or a "direct connection state" (see FIG. 7). In the third transmission state, power from the drive source 10 is directly transmitted from the second input / output shaft 42 a to the output shaft 52.

  Furthermore, in the present embodiment, in addition to the above-described respective shift states, the following shift states are taken. The state in which the first sleeve 72 is in the front position and the second sleeve 74 is in the rear position is referred to as "first intermediate transmission state" (see FIG. 4).

  In the first intermediate transmission state, the motive power from the drive source 10 is transmitted from the second input / output shaft 42 a via the second input gear 56, the first sub gear 53, the second sub gear 54, and the first output gear 58. It is transmitted to the output shaft 52 and is also transmitted from the first input / output shaft 41 a to the output shaft 52 via the first input gear 55 and the second output gear 59.

  Further, in the first intermediate transmission state, the capacities of the first pump motor 41 and the second pump motor 42 are adjusted, and the first pump motor 41 and the second pump motor 42 do not work.

  A state in which the first sleeve 72 is in the front position and the second sleeve 74 is in the front position is referred to as a "second intermediate transmission state" (see FIG. 6).

  In the second intermediate transmission state, power from the drive source 10 is transmitted from the first input / output shaft 41 a to the output shaft 52 via the first input gear 55 and the second output gear 59, and The power is transmitted directly from the output shaft 42 a to the output shaft 52.

  Further, in the second intermediate transmission state, the capacities of the first pump motor 41 and the second pump motor 42 are adjusted, and the first pump motor 41 and the second pump motor 42 do not work.

  In the present embodiment, the number of teeth of the second input gear 56, the first sub gear 53, the second sub gear 54, and the first output gear 58 reduces the rotation of the second input / output shaft 42a in the first transmission state. Is set to be transmitted to the output shaft 52. Further, the number of teeth of the first input gear 55 and the second output gear 59 is set such that the rotation of the first input / output shaft 41a is decelerated and transmitted to the output shaft 52 in the second transmission state. .

  The gear ratio in the first transmission state (rotational speed of the second input / output shaft 42a / rotational speed of the output shaft 52) is α1, the transmission gear ratio in the second transmission state (rotational speed of the first input / output shaft 41a / output shaft 52 Assuming that the rotation speed is α2, α1> α2> 1. The relationship between α1, α2 and 1 (direct connection) is not limited to this. Specifically, for example, it is possible to set α1 <α2 <1.

  Returning to FIG. 1, the control device 80 includes the drive source 10, the hydraulic transmission unit 40 (the first pump motor 41, the second pump motor 42), and the stepped transmission unit 50 (the first sleeve 72, the second sleeve 74). Take control.

  The control device 80 controls an engine control unit 81 that controls the drive source 10, a hydraulic shift control unit 82 that controls the first pump motor 41 and the second pump motor 42, and a first sleeve 72 and a second sleeve 74. An engagement mechanism control unit 83 is provided as a functional element.

  In the present embodiment, the engine control unit 81, the hydraulic shift control unit 82, and the engagement mechanism control unit 83 are described as being included in the control device 80, but the hydraulic shift control unit 82 and the engagement mechanism control unit 83 Each can be independent hardware.

  Next, the gear change operation will be described with reference to FIGS. 3 to 7 are skeleton diagrams in each transmission state. FIG. 8 is a diagram showing the relationship between the speed ratio and the displacement volume.

  The start of the vehicle 1 is performed in the first transmission state shown in FIG. In this case, the first pump motor 41 operates as a pump, and the second pump motor 42 operates as a motor. In the following description, “operate as a pump” and “operate as a motor” refer to the first pump when the vehicle 1 is driven by the drive source 10 (that is, when the tire is performing positive work) The role of the motor 41 and the second pump motor 42 is referred to. When the vehicle 1 is driven from the wheel side (i.e., when the engine brake is applied), the roles of the pump and the motor are reversed.

  In order to start the vehicle 1, the displacement volume of the first pump motor 41 operating as a pump is gradually increased from zero while holding the displacement volume of the second pump motor 42 at a maximum. By doing this, as shown in FIG. 8, the speed ratio (the rotation speed Nout of the output shaft 52 / the rotation speed Nin of the drive source 10) rises from zero.

  At this time, when the engine torque is controlled so that the discharge pressure from the first pump motor 41 to the second pump motor 42 becomes constant (that is, the engine torque is increased according to the increased pump-side displacement volume) (In the case where it is made), the torque generated by the second pump motor 42 becomes constant. Further, the torque transmitted from the differential gear to the second input / output shaft 42a of the second pump motor 42 is increased. Therefore, the torque transmitted to the output shaft 52 is increased.

  When the displacement volume of the first pump motor 41 is maximum, the displacement volume of the second pump motor 42 operating as a motor is gradually directed toward zero while maintaining the displacement volume of the first pump motor 41 at a maximum. Reduce it to By doing this, the speed ratio is further increased.

  When the displacement volume of the second pump motor 42 is gradually decreased and the displacement volume of the second pump motor 42 becomes Q1, the rotational speed of the first input hub 41b (ie, the rotation of the first input / output shaft 41a Number) and the rotational speed of the first input gear 55 match. At this timing, the shift from the first transmission state to the first intermediate transmission state is performed. The specific content will be described later.

  In the first intermediate transmission state, the power from the drive source 10 is output from the first input / output shaft 41a and the second input / output shaft 42a to the output shaft 52 without being converted to the hydraulic pressure in the hydraulic transmission unit 40. Therefore, the first intermediate transmission state has better transmission efficiency than the first transmission state and the second transmission state.

  Furthermore, a shift from this state to the second transmission state is performed. When the shift to the second transmission state is completed, the first pump motor 41 operating as a pump in the first transmission state operates as a motor, and the second pump motor 42 operating as a motor operates as a pump It will be done.

  Subsequently, in a state where the displacement volume of the first pump motor 41 is held at the maximum, the displacement volume of the second pump motor 42 operating as a pump is gradually increased from Q1. By doing this, the speed ratio is further increased.

  When the displacement volume of the second pump motor 42 is maximum, the displacement volume of the first pump motor 41 operating as a motor is gradually directed toward zero while maintaining the displacement volume of the second pump motor 42 at a maximum. Reduce it to By doing this, the speed ratio is further increased.

  When the displacement volume of the first pump motor 41 is gradually decreased and the displacement volume of the first pump motor 41 becomes Q2, the rotational speed of the second input hub 42b (ie, the rotation of the second input / output shaft 42a) And the number of rotations of the output hub 57 (that is, the number of rotations of the output shaft 52). At this timing, the shift from the second transmission state to the second intermediate transmission state is performed.

  In the second intermediate transmission state, the power from the drive source 10 is output from the first input / output shaft 41a and the second input / output shaft 42a to the output shaft 52 without being converted to the hydraulic pressure in the hydraulic transmission unit 40. Therefore, the second intermediate transmission state has better transmission efficiency than the second transmission state and the third transmission state.

  Furthermore, a shift from this state to the third transmission state is performed. When the shift to the third transmission state is completed, the second pump motor 42 operating as a pump in the second transmission state operates as a motor, and the first pump motor 41 operating as a motor operates as a pump It will be done.

  Subsequently, in a state where the displacement volume of the second pump motor 42 is maintained at a maximum, the displacement volume of the first pump motor 41 operating as a pump is gradually increased from Q2. By doing this, the speed ratio is further increased.

  When the displacement volume of the first pump motor 41 is maximum, the displacement volume of the second pump motor 42 operating as a motor is gradually directed toward zero while maintaining the displacement volume of the first pump motor 41 at a maximum. Reduce it to By doing this, the speed ratio is further increased. Then, the speed ratio increases until the displacement volume of the second pump motor 42 becomes substantially zero.

  The same applies to the case where the speed ratio is decreased, and the third transmission state to the second intermediate transmission state, the second intermediate transmission state to the second transmission state, the second transmission state to the first intermediate transmission state, and the first intermediate transmission. The shift from the state to the first transmission state is sequentially performed.

  In this embodiment, when shifting from the first intermediate transmission state to the first transmission state or to the second transmission state, and when shifting from the second intermediate transmission state to the second transmission state or the third transmission state, the first or The movement of the second sleeves 72, 74 and the change of the displacement volume of the first or second pump motor 41, 42 are coordinated.

  The coordinated shift control process from the first intermediate transmission state to the second transmission state will be described as an example with reference to the flowchart of FIG. 9.

  In step S1, the control device 80 (specifically, the engagement mechanism control unit 83) generates an urging force for moving the second sleeve 74 from the rear position to the central position. In this state, since torque is transmitted between the output hub 57 and the second sleeve 74, the frictional force between the output hub 57 and the second sleeve 74 is larger than the biasing force. Therefore, the sleeve does not move by the biasing force, and the second connection mechanism 73 remains in the engaged state.

  In the subsequent step S2, the control device 80 (specifically, the hydraulic shift control unit 82) controls the second pump motor 42 so that the torque passing through the second connection mechanism 73 is reduced. Specifically, the control device 80 controls the second pump motor 42 such that the displacement volume of the second pump motor 42 is increased.

  When the force applied to the second sleeve 74 exceeds the frictional force between the output hub 57 and the second sleeve 74 as the torque passing through the second coupling mechanism 73 decreases, the second sleeve 74 Move from position to center position. At this time, the torque passing through the second connection mechanism 73 is not zero.

  The transmission from the first intermediate transmission state to the second transmission state also for the transmission from the first intermediate transmission state to the first transmission state and from the second intermediate transmission state to the second transmission state or the third transmission state The same is done.

  The drive source 10 may be controlled in addition to cooperative control of the first connection mechanism 71 or the second connection mechanism 73 and the first pump motor 41 or the second pump motor 42. In this case, the control device 80 controls the drive source 10 such that the torque passing through the coupling mechanism being disengaged is reduced. Specifically, for example, when the vehicle 1 is driven by the drive source 10, the output torque of the drive source 10 is reduced. Also, for example, when the vehicle 1 is driven from the wheel side, the output torque of the drive source 10 is increased.

  As described above, according to the present embodiment, the control device 80 engages the engagement of the first connection mechanism 71 or the second connection mechanism 73 in a state where the first connection mechanism 71 and the second connection mechanism 73 are both engaged. The displacement volume of the first pump motor 41 or the second pump motor 42 is controlled so as to reduce the torque passing through the engagement mechanism being disengaged while urging in the direction to cancel the engagement. Therefore, it is possible to shift quickly.

  Further, according to the present embodiment, the drive source 10 is further controlled to reduce the torque passing through the engagement mechanism being disengaged. Therefore, it is possible to shift quickly.

  In the above embodiment, although the differential mechanism is a bevel gear type differential mechanism, the present invention is not limited to this. A well-known structure can be suitably adopted as a differential mechanism. Specifically, for example, the differential mechanism may be a planetary gear mechanism.

  Further, in the above-described embodiment, although the stepped transmission is configured such that the first input / output shaft side is one stage and the second input / output shaft side is two stages, a total of three stages are provided, the present invention is not limited thereto. Specifically, for example, the first input / output shaft may have two stages, and the first input / output shaft may have one stage.

  Further, in the present embodiment, although the number of shift speeds in the stepped transmission unit is three, the present invention is not limited to this. Specifically, for example, a transmission mechanism that shifts the rotational force of the first input / output shaft and transmits it to the output shaft is provided, and the first input / output shaft side has two stages, and the second input / output shaft side has two stages. It may be In this case, each gear ratio is set to alternately use the first input / output shaft and the second input / output shaft. Furthermore, it is also possible to make the number of shift stages from each input / output shaft to the output shaft 3 or more, and to achieve further multistage. Also, conversely, it is possible to perform low-speed and high-speed two-step switching having only one transmission path from the first input / output axis to the output axis and one transmission path from the second input / output axis to the output axis.

  The shift control device of the present invention is suitably used for a vehicle that is required to shift quickly.

Reference Signs List 1 vehicle 10 drive source 11 output shaft 20 damper 21 input side member 22 output side member 23 elastic connecting member 30 differential mechanism 31 input shaft 32 bevel gear 33 first differential output gear 34 second differential output gear 35 differential output shaft 36 1st gear 37 2nd gear 40 hydraulic transmission section 41 1st pump motor 41a 1st input / output shaft 41b 1st input hub 42 2nd pump motor 42a 2nd input / output shaft 42b 2nd input hub 43 closed circuit 50 stepped Transmission unit 51 Secondary shaft 52 Output shaft 53 First secondary gear 54 Second secondary gear 55 First input gear 55a First clutch gear 56 Second input gear 57 Output hub 58 First output gear 58a Output clutch gear 59 Second output gear 61 propeller shaft 62 differential 63 drive shaft 64 drive wheel 71 first connection mechanism 72 first sleeve 73 second connection mechanism 74 second sleeve 80 control device 81 engine control unit 82 hydraulic shift control unit 83 engagement mechanism control unit

Claims (2)

A hydraulic transmission unit in which one and the other variable displacement pump motors are connected by a closed circuit to which power from the drive source divided into two by the differential mechanism is input, and the one and the other variable displacement pump motors And a geared transmission having first and second engagement mechanisms capable of outputting the power of the input / output shaft to the output shaft, respectively.
A first control unit configured to bias the first or second engagement mechanism in a direction in which the first or second engagement mechanism is disengaged with the first and second engagement mechanisms engaged together;
With one or the other variable to reduce the torque passing through the first or second engagement mechanism while biasing the first or second engagement mechanism in the disengaging direction And a second control unit configured to control a displacement pump motor. The drive source is controlled to reduce the torque passing through the first or second engagement mechanism while biasing the first or second engagement mechanism in the disengaging direction. The shift control device according to claim 1, comprising a third control unit.

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