JP2019049291A - Driving force control device - Google Patents

Abstract

To provide a driving force control device capable of securing temporarily high driving force.SOLUTION: The driving force control device, which is used for a vehicle mounted with a transmission including a hydraulic transmission unit connecting via a closed circuit one variable displacement pump motor and the other to which one power and the other from a driving source, split in two with a differential mechanism, is input, respectively, and a stepped transmission unit having a first engagement mechanism capable of outputting the power of the input/output shaft of one variable displacement pump motor to the output shaft while shifting gears into a plurality of transmission gear ratios and a second engagement mechanism capable of outputting the power of the input/output shaft of the other variable displacement pump motor to the output shaft at transmission gear ratios different from the plurality of transmission gear ratios, includes a driving source control unit for controlling the driving source to increase the torque of the driving source when an increase in the driving force of the vehicle is requested, and a shift control unit for controlling one variable displacement pump motor or the other to relieve of pressure oil from a high pressure oil path to a low pressure oil path via a relief valve provided between the high pressure oil path and the low pressure oil path of the closed circuit.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a driving force 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.

  Then, at the time of start of the vehicle, in the low speed mode, the displacement volume of the other hydraulic pump motor is increased from zero while maintaining the displacement volume of one of the hydraulic pump motors at maximum.

  By the way, at the time of start of a vehicle at the time of high loading, climbing a hill, etc., there may be a case where the driving force necessary for starting can not be secured. In addition, a high driving force may be required temporarily while the vehicle is traveling. However, Patent Document 1 does not disclose how to secure the driving force in those cases.

  An object of the present invention is to provide a driving force control device capable of temporarily securing a high driving force.

  The driving force control apparatus according to the present invention is a hydraulic shift in which one and the other variable displacement pump motors, to which one and the other of the power from the driving source divided into two by a differential mechanism are input, are connected by a closed circuit. First engaging mechanism capable of shifting the power of the input / output shaft of one variable displacement pump motor to a plurality of transmission ratios and outputting the power to the output shaft, and the input of the other variable displacement pump motor A geared transmission having a second engagement mechanism capable of outputting the power of the output shaft to the output shaft at a gear ratio different from the plurality of gear ratios, and used in a vehicle equipped with a transmission A force control device, wherein a drive source control unit controls the drive source so as to increase a torque of the drive source when an increase in the drive force of the vehicle is requested, and a high pressure oil of the closed circuit Relief valve provided between the low pressure oil passage and the low pressure oil passage And so as to relief the pressure oil to the low pressure oil passage from the high pressure oil path, and a transmission control unit for controlling the variable displacement pump motor of the one or the other.

  According to the driving force control device according to the present invention, a high driving force can be temporarily secured.

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 Flow chart showing processing of high torque start control Time chart showing transition of each parameter at the time of start Time chart showing transition of each parameter at the time of start Flow chart showing processing of temporary high torque control Time chart showing transition of each parameter at the time of temporary high torque control execution

  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. Further, the closed circuit 43 is provided with a relief valve 44 which opens when the hydraulic pressure of the high pressure side oil passage 43a becomes equal to or higher than a predetermined hydraulic pressure, and discharges the pressure oil to the low pressure side oil passage 43b. In FIG. 1, some components (charge pump, charge oil passage, etc.) in the closed circuit 43 are omitted.

  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.

  Here, 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, the stepped transmission unit 50 takes the shift state described below in addition to the above-described each shift state. 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 controller 80 controls an engine control unit 81 (the “drive source control unit” of the present invention) that controls the drive source 10, and a hydraulic shift control unit 82 that controls the first pump motor 41 and the second pump motor 42 (the present invention And a engagement mechanism control unit 83 for controlling the first sleeve 72 and the second sleeve 74 as functional elements.

  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. However, the engine control unit 81, the hydraulic shift control unit 82, and the engagement The mechanism control unit 83 may be hardware independent of one another.

  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 output torque of the drive source 10 is controlled so that the discharge pressure from the first pump motor 41 to the second pump motor 42 becomes constant (that is, the drive source according to the pump side displacement volume to be increased). In the case where the output torque of 10 is increased), the torque generated by the second pump motor 42 is 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. Specifically, the first sleeve 72 is moved to the front position (see FIG. 4). Thus, the power from the drive source 10 is transmitted from the second input / output shaft 42 a to the output shaft 52 via the second input gear 56, the first auxiliary gear 53, the second auxiliary gear 54 and the first output gear 58. While being transmitted, it is transmitted to the output shaft 52 from the first input / output shaft 41 a via the first input gear 55 and the second output gear 59.

  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. Specifically, the second sleeve 74 is moved from the rear position to the central position, and the power transmission from the second input / output shaft 42a of the second pump motor 42 to the output shaft 52 is interrupted (see FIG. 5). 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. Specifically, the second sleeve 74 is moved to the front position (see FIG. 6). Thus, the power from the drive source 10 is transmitted from the first input / output shaft 41a to the output shaft 52 via the first input gear 55 and the second output gear 59, and from the second input / output shaft 42a. , Output shaft 52 directly.

  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. Specifically, the first sleeve 72 is moved from the front position to the rear position, and power transmission from the first input / output shaft 41a of the first pump motor 41 to the output shaft 52 is cut off (see FIG. 7). 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.

  Next, high torque start will be described with reference to FIGS. 9, 10A and 10B. FIG. 9 is a flowchart showing processing of high torque start control. 10A and 10B show displacement volumes of the first pump motor 41 and the second pump motor 42 and discharges of the first pump motor 41 and the second pump motor 42 at the time of normal start and high torque start, respectively. 7) A time chart showing the transition of the flow rate and the pressure P in the high pressure side oil passage 43a.

  First, high torque start control processing will be described with reference to the flowchart of FIG. The process shown in FIG. 9 is executed when a high torque start request is made. Here, “when a high torque start request is made” means, for example, that the vehicle 1 remains stopped although the pressure P of the high pressure side oil passage 43 a in the hydraulic transmission unit 40 has reached the relief pressure. In this state, it refers to the case where the driver steps on the accelerator pedal further.

  In step S1, the control device 80 (specifically, the drive source control unit 81) controls the drive source 10 to increase the output torque of the drive source 10.

  In step S2, the control device 80 (specifically, the transmission control unit 82) controls the first pump motor 41 to increase the displacement volume of the first pump motor 41.

  Next, with reference to FIGS. 10A and 10B, the start operation at the time of start of the vehicle will be described. First, a normal start operation will be described with reference to FIG. 10A. At time t0, for start-up, the displacement volume of the second pump motor 42 operating as a motor is maximized, and the displacement volume of the first pump motor 41 operating as a pump is zero. Then, pressure oil is supplied from the first pump motor 41 to the high pressure side oil passage 43a by the rotation of the drive source 10, and the pressure P in the high pressure side oil passage 43a rises from time t0 to time t1.

  At time t1, the pressure P in the high pressure side oil passage 43a becomes P1 (P = P1). Actually, the pressure P of the high pressure side oil passage 43a instantaneously reaches P1, but in FIG. 10A, the length from time t0 to time t1 is exaggerated. P1 is the pressure in the high pressure side oil passage 43a corresponding to the torque required for the vehicle 1 to move. Thus, at time t1, the vehicle 1 starts moving.

  After time t1, the displacement volume of the first pump motor 41 is increased according to the passage of time based on the control signal from the control device 80, and the discharge flow rate is increased. Further, the suction flow rate of the second pump motor 42 is increased by receiving all the pressure oil discharged by the first pump motor 41.

Next, with reference to FIG. 10B, a case where the starting torque of the vehicle 1 can not be secured in a normal starting operation due to high loading, climbing, and the like will be described. In FIG. 10B, the pressure P2 in the high pressure side oil passage 43a corresponding to the torque required for the vehicle 1 to move is described. The pressure P2 is a pressure higher than the relief pressure P _MAX .

  At the time of high loading, climbing up, etc., even if the pressure P in the high pressure side oil passage 43a becomes P1 at time t11, the vehicle 1 can not be started.

At time t12, the pressure P in the high pressure side oil passage 43a reaches the relief pressure P _MAX , and the pressure oil in the high pressure side oil passage 43a is discharged to the low pressure side oil passage 43b via the relief valve 44. In this situation, for example, at time t13, when the driver desires to start moving and depresses the accelerator pedal further, the above-described high torque start control is performed. That is, as the depression of the accelerator pedal is increased, the output torque of the drive source 10 is increased. At the same time, the displacement volume of the first pump motor 41 is increased.

Since the displacement volume of the first pump motor 41 is increased, as shown in FIG. 10B, the discharge flow rate of the pump and the suction flow rate of the motor do not match, so only the discharge flow rate from the first pump motor 41 Increases. At this point in time, the pressure in the high pressure side oil passage 43a has reached the relief pressure P _MAX , so the pressure oil in the high pressure side oil passage 43a is discharged to the low pressure side oil passage 43b via the relief valve 44. .

  On the other hand, as the output torque of the drive source 10 is increased, the torque transmitted to the second input / output shaft 42a via the mechanical transmission path also increases. Then, at time t14, when the total torque of the torque via the hydraulic transmission path and the torque via the mechanical transmission path transmitted to the second input / output shaft 42a reaches the torque necessary for the start of the vehicle 1, the vehicle 1 takes off.

  After time t14, the displacement volume of the first pump motor 41 is increased according to the passage of time based on the control signal from the control device 80, and the discharge flow rate is increased. In addition, the second pump motor 42 receives part of the pressure oil discharged by the first pump motor 41. Therefore, the suction flow rate of the second pump motor 42 is increased by the increase of the vehicle speed (the increase of the rotational speed of the second pump motor 42), and the suction flow rate of the second pump motor 42 is calculated from the discharge flow rate of the first pump motor 41. The reduced amount of pressure oil is discharged to the low pressure side oil passage 43 b via the relief valve 44.

  Next, temporary high torque control will be described with reference to FIGS. 11 and 12. FIG. 11 is a flowchart showing the process of temporary high torque control. Further, FIG. 12 shows displacement volumes of the first pump motor 41 and the second pump motor 42, discharge (intake) flow rates of the first pump motor 41 and the second pump motor 42, and temporary high torque control execution. It is a time chart which shows transition of pressure P in high-pressure side oilway 43a.

  First, temporary high torque control processing will be described with reference to the flowchart of FIG. The process shown in FIG. 11 is executed when the driver temporarily makes a high torque request in the first, second or third transmission state. Here, "when a high torque request is temporarily made" means, for example, a case where the driver steps on the accelerator pedal further.

  In step S11, the control device 80 determines whether the displacement volume of the pump motor operating as a pump among the first pump motor 41 or the second pump motor 42 in the hydraulic transmission unit 40 is not maximum. .

If the displacement volume of the pump is the largest (step S11: NO), the temporary high torque control process is ended. In this case, the accelerator pedal is further depressed and the output torque of the drive source 10 is increased, so that the pressure P in the high pressure side oil passage 43a is increased to balance the output torque of the drive source 10. . Then, when the pressure P in the high-pressure side oil passage 43a reaches the relief pressure P _MAX , the system becomes in the maximum torque state. On the other hand, when the displacement volume of the pump is not the largest (step S1: YES), the process proceeds to step S12.

In step S12, the control device 80 controls the drive source 10 to increase the output torque of the drive source 10. With the increase of the output torque of the driving source 10, the pressure P in the high pressure side oil passage 43a rises so as to balance the output torque of the drive source 10, and reaches the relief pressure P _MAX.

  In the following step S13, the control device 80 controls the pump motor operating as a pump among the first pump motor 41 or the second pump motor 42 to increase the displacement volume.

  Next, with reference to FIG. 12, an operation at the time of temporarily putting the vehicle 1 in the high torque state without changing the transmission state during traveling will be described. In the example shown in FIG. 12, while traveling with the displacement volume of the pump motor operating as a pump constant, the driver requests a temporary increase in torque to increase the depression of the accelerator pedal. Case is shown.

At time t21, when the driver further depresses the accelerator pedal, the pressure P in the high pressure side oil passage 43a rises with the increase of the output torque of the drive source 10, and reaches the relief pressure _PMAX . When the depression of the accelerator pedal is further performed from here, the above-described temporary high torque control is performed. That is, at time t21, since the displacement volume of the pump is not maximum, the output torque of the drive source 10 is increased as the depression of the accelerator pedal is increased. At the same time, the displacement of the pump is increased.

By increasing the displacement of the pump, the discharge flow rate from the pump is increased. Further, the pressure in the high pressure side oil passage 43a reaches the relief pressure P _MAX , and the pressure oil in the high pressure side oil passage 43a is, as shown in FIG. 12, the discharge flow rate of the pump and the suction flow rate of the motor Since they do not match, they are discharged to the low pressure side oil passage 43 b through the relief valve 44.

  On the other hand, as the output torque of the drive source 10 is increased, the torque transmitted to the input / output shaft of the motor in the mechanical transmission path is also increased. Therefore, the sum of the torque transmitted via the hydraulic transmission path and the torque transmitted via the mechanical transmission path, which is transmitted to the input / output shaft of the motor, increases.

  In the example shown in FIG. 12, at time t22, the depression amount of the accelerator pedal is returned to the state before time t21. Along with this, the displacement volume of the pump is also returned to the state before time t21. Therefore, after time t22, the discharge flow rate of the pump and the suction flow rate of the motor match.

  As described above, according to the present embodiment, when an increase in the driving force of the vehicle is required, the control device 80 increases the output torque of the driving source 10, and the first pump motor 41 and the second pump motor 41 and the second Among the pump motors 42, the pump motor operating as a pump is controlled to increase the displacement volume.

  As a result, a part of the pressure oil in the high pressure side oil passage 43a is discharged to the low pressure side oil passage 43b via the relief valve 44, but the output torque of the drive source 10 is increased. The torque transmitted to the input / output shaft of the motor in the formula transmission path also increases. Therefore, a high driving force can be temporarily secured.

  Further, according to the present embodiment, the following effects can be obtained.

  In high load, there is no need to prepare a low speed gear to start the vehicle at the time of hill climbing. Therefore, it is possible to reduce the number of shift speeds of the stepped transmission unit. Alternatively, the gear ratio in each gear can be set to be high (close to high speed).

  Further, when the vehicle is traveled at a speed ratio close to the switching point of the transmission state, it is not necessary to switch the transmission state in order to temporarily increase the torque. For example, there is no need to switch the stepped transmission unit 50 to the first transmission state in order to temporarily increase the torque during traveling in the second transmission state.

  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 further increase the number of stages on the high speed side. 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 driving force control device of the present invention is suitably used for a vehicle that temporarily requires a high driving force.

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 (3)

A hydraulic transmission unit in which one and the other variable displacement pump motors from which one and the other of the power from the drive source divided into two by the differential mechanism are input are connected by a closed circuit, and the one variable displacement pump The first engagement mechanism capable of shifting the power of the input / output shaft of the motor to a plurality of gear ratios and outputting the power to the output shaft, and the power of the input / output shaft of the other variable displacement pump motor to the plurality of gear ratios And a geared transmission having a second engagement mechanism capable of outputting to the output shaft at a gear ratio different from that of the drive power control device used in a vehicle equipped with a transmission.
A drive source control unit configured to control the drive source so as to increase a torque of the drive source when an increase in the drive force of the vehicle is required;
One or the other variable displacement pump such that pressure oil is relieved from the high pressure oil passage to the low pressure oil passage via a relief valve provided between the high pressure oil passage and the low pressure oil passage of the closed circuit. And a shift control unit that controls the motor. The transmission control unit increases the displacement volume of the variable displacement pump motor operating as a pump among the one or the other variable displacement pump motors.
The driving force control device according to claim 1. The request for increasing the driving force of the vehicle is made by increasing the depression of the accelerator pedal by the driver.
The driving force control device according to claim 1.

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