WO2023189023A1 - Work vehicle and method for controlling work vehicle - Google Patents

Work vehicle and method for controlling work vehicle Download PDF

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Publication number
WO2023189023A1
WO2023189023A1 PCT/JP2023/006301 JP2023006301W WO2023189023A1 WO 2023189023 A1 WO2023189023 A1 WO 2023189023A1 JP 2023006301 W JP2023006301 W JP 2023006301W WO 2023189023 A1 WO2023189023 A1 WO 2023189023A1
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WO
WIPO (PCT)
Prior art keywords
clutch
work vehicle
transmission
transmission oil
speed clutch
Prior art date
Application number
PCT/JP2023/006301
Other languages
French (fr)
Japanese (ja)
Inventor
慎一 内藤
Original Assignee
株式会社小松製作所
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Publication of WO2023189023A1 publication Critical patent/WO2023189023A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D25/00—Fluid-actuated clutches
    • F16D25/06—Fluid-actuated clutches in which the fluid actuates a piston incorporated in, i.e. rotating with the clutch
    • F16D25/062—Fluid-actuated clutches in which the fluid actuates a piston incorporated in, i.e. rotating with the clutch the clutch having friction surfaces
    • F16D25/063—Fluid-actuated clutches in which the fluid actuates a piston incorporated in, i.e. rotating with the clutch the clutch having friction surfaces with clutch members exclusively moving axially
    • F16D25/0635—Fluid-actuated clutches in which the fluid actuates a piston incorporated in, i.e. rotating with the clutch the clutch having friction surfaces with clutch members exclusively moving axially with flat friction surfaces, e.g. discs
    • F16D25/0638—Fluid-actuated clutches in which the fluid actuates a piston incorporated in, i.e. rotating with the clutch the clutch having friction surfaces with clutch members exclusively moving axially with flat friction surfaces, e.g. discs with more than two discs, e.g. multiple lamellae
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D48/00—External control of clutches
    • F16D48/02—Control by fluid pressure

Definitions

  • the present disclosure relates to a work vehicle and a method of controlling the work vehicle.
  • Patent Document 1 discloses a warm-up circuit that raises the temperature of transmission oil (hydraulic oil) used for driving a clutch in a transmission and lubricating a clutch disk when a work vehicle is started.
  • transmission oil hydroaulic oil
  • An object of the present disclosure is to provide a work vehicle and a method for controlling a work vehicle that can remove water mixed into transmission oil with a simple configuration.
  • a work vehicle includes a clutch having a plurality of clutch discs lubricated by transmission oil, and a controller that controls engagement and disengagement of the clutch.
  • the controller moves the plurality of clutch disks to a standby position between an initial position and an engaged position in response to a request for raising the temperature of transmission oil.
  • FIG. 1 is a side view of a work vehicle 1 according to the embodiment.
  • Work vehicle 1 is a wheel loader.
  • a work vehicle 1 includes a vehicle body 2 and a work machine 3.
  • the vehicle body 2 includes a front vehicle body 2a and a rear vehicle body 2b.
  • the rear vehicle body 2b is connected to the front vehicle body 2a so as to be swingable from side to side.
  • a hydraulic cylinder 15 is connected to the front vehicle body 2a and the rear vehicle body 2b. As the hydraulic cylinder 15 expands and contracts, the front vehicle body 2a swings left and right with respect to the rear vehicle body 2b.
  • the work machine 3 is used for work such as excavation.
  • the working machine 3 is attached to the front vehicle body 2a.
  • the work machine 3 includes a boom 11, a bucket 12, and hydraulic cylinders 13 and 14.
  • the boom 11 and bucket 12 operate as the hydraulic cylinders 13 and 14 expand and contract.
  • the work vehicle 1 includes an engine 21, a transmission 22, and a traveling device 23.
  • Engine 21 is, for example, an internal combustion engine such as a diesel engine.
  • Transmission 22 is connected to engine 21 . Transmission oil is sealed inside the transmission 22. The configuration of the transmission 22 will be described later.
  • the traveling device 23 causes the work vehicle 1 to travel.
  • the traveling device 23 has front wheels 24 and rear wheels 25.
  • the front wheels 24 are provided on the front vehicle body 2a.
  • the rear wheel 25 is provided on the rear vehicle body 2b.
  • the front wheels 24 and the rear wheels 25 are connected to the transmission 22 via an axle (not shown).
  • the work vehicle 1 is equipped with a hydraulic pump (not shown).
  • a hydraulic pump is connected to the engine 21.
  • the hydraulic pump is driven by the engine 21 and discharges transmission oil.
  • Transmission oil discharged from the hydraulic pump is supplied to the transmission 22.
  • the transmission oil is used both to drive each clutch (a low-speed clutch 71, a high-speed clutch 72, and a medium-speed clutch 73, which will be described later) included in the transmission 22, and to lubricate a clutch disk included in each clutch.
  • the work vehicle 1 includes a controller 27.
  • the controller 27 includes, for example, a processor and a memory. Controller 27 controls engine 21 and transmission 22. The functions of the controller 27 will be described later.
  • FIG. 2 is a skeleton diagram showing the configuration of the transmission 22. As shown in FIG.
  • the transmission 22 is a so-called HMT (hydraulic-mechanical transmission).
  • the transmission 22 includes an input shaft 31, an output shaft 32, a first planetary gear mechanism 33, a second planetary gear mechanism 34, a third planetary gear mechanism 35, a first variable device 36, and a second variable A device 37 is provided.
  • the input shaft 31 is connected to the engine 21.
  • the output shaft 32 is connected to the traveling device 23.
  • the first planetary gear mechanism 33, the second planetary gear mechanism 34, and the third planetary gear mechanism 35 are arranged coaxially.
  • the input shaft 31 and the output shaft 32 are arranged eccentrically from the central axis C1 of the first planetary gear mechanism 33, the second planetary gear mechanism 34, and the third planetary gear mechanism 35, respectively.
  • the first planetary gear mechanism 33 includes a first carrier 41 , a plurality of first planetary gears 42 , a first sun gear 43 , and a first ring gear 44 .
  • An input gear 45 is fitted onto the input shaft 31 .
  • the first carrier 41 includes an external gear 46 . By meshing the gear 46 and the input gear 45, the first carrier 41 is connected to the input shaft 31.
  • the first planetary gear 42 is connected to the first carrier 41 and is rotatable together with the first carrier 41 around the central axis C1.
  • the first sun gear 43 is fitted onto the shaft 55 and can rotate integrally with the shaft 55.
  • the first sun gear 43 meshes with the first planetary gear 42.
  • the first ring gear 44 meshes with the first planetary gear 42.
  • the second planetary gear mechanism 34 includes a second sun gear 51, a plurality of second planetary gears 52, a second carrier 53, and a second ring gear 54.
  • the second sun gear 51 is connected to the first carrier 41 and is rotatable together with the first carrier 41 around the central axis C1.
  • the second sun gear 51 can idle around the shaft 55.
  • the second planetary gear 52 meshes with the second sun gear 51.
  • the second carrier 53 is connected to the second planetary gear 52 and is rotatable together with the second planetary gear 52 around the central axis C1.
  • the second ring gear 54 meshes with the second planetary gear 52.
  • the second ring gear 54 is connected to the first ring gear 44.
  • the first ring gear 44 and the second ring gear 54 are integrally formed and constitute a ring member 47.
  • the outer peripheral surface of the ring member 47 includes an external gear 48 .
  • Gear 48 is connected to first variable device 36 .
  • the first variable device 36 is a hydraulic pump/motor.
  • the capacity of the first variable device 36 is controlled by the controller 27.
  • the controller 27 continuously changes the speed ratio of the output shaft 32 to the input shaft 31 by controlling the rotational speed of the first variable device 36 .
  • a gear 49 is fitted onto the rotating shaft of the first variable device 36 . Gear 49 meshes with gear 48 described above.
  • the third planetary gear mechanism 35 includes a third carrier 61, a plurality of third planetary gears 62, a third sun gear 63, and a third ring gear 64.
  • the third carrier 61 is connected to the second carrier 53 and is rotatable together with the second carrier 53 around the central axis C1.
  • the third carrier 61 may be integrated with the second carrier 53 or may be separate.
  • the third planetary gear 62 is connected to the third carrier 61 and is rotatable together with the third carrier 61 around the central axis C1.
  • the third sun gear 63 meshes with the third planetary gear 62.
  • the third sun gear 63 can idle around the shaft 55.
  • the third ring gear 64 meshes with the third planetary gear 62.
  • Third ring gear 64 is non-rotatable.
  • the third ring gear 64 is fixed to the housing of the transmission 22, for example.
  • the third planetary gear mechanism 35 accelerates the rotation from the second planetary gear mechanism 34 and outputs it.
  • the second variable device 37 is a hydraulic pump/motor.
  • the second variable device 37 is connected to the first variable device 36 by a hydraulic circuit (not shown).
  • the first variable device 36 functions as a pump and discharges transmission oil
  • the second variable device 37 functions as a motor and is driven by the transmission oil from the first variable device 36.
  • the first variable device 36 functions as a motor and is driven by the transmission oil from the second variable device 37.
  • the capacity of the second variable device 37 is controlled by the controller 27.
  • the controller 27 continuously changes the speed ratio by controlling the rotational speed of the second variable device 37.
  • the second variable device 37 is arranged coaxially with the second planetary gear mechanism 34 .
  • a shaft 55 is connected to the rotation axis of the second variable device 37.
  • the first sun gear 43 is fitted onto the shaft 55 .
  • Shaft 55 connects first sun gear 43 and second variable device 37 .
  • the shaft 55 is arranged coaxially with the first to third planetary gear mechanisms 33 to 35.
  • the transmission 22 includes a low speed gear 65, a high speed gear 66, a medium speed gear 67, a low speed clutch 71, a high speed clutch 72, and a medium speed clutch 73.
  • the low speed gear 65, high speed gear 66, and medium speed gear 67 are arranged coaxially with the first to third planetary gear mechanisms 33 to 35.
  • the low-speed gear 65 is fitted onto the shaft 55 and is rotatable together with the shaft 55 around the central axis C1.
  • Low speed gear 65 is connected to output shaft 32 via low speed clutch 71.
  • the high-speed gear 66 is connected to the shaft 55 via a high-speed clutch 72. When high speed clutch 72 is engaged, high speed gear 66 is rotatable with shaft 55 . High speed gear 66 is connected to output shaft 32 .
  • the medium speed gear 67 is connected to the third sun gear 63 and can rotate together with the third sun gear 63 around the central axis C1. The medium speed gear 67 may be integrated with the third sun gear 63 or may be separate from the third sun gear 63.
  • Each of the low-speed clutch 71, high-speed clutch 72, and medium-speed clutch 73 is a hydraulic wet multi-disc clutch having a plurality of clutch discs. The engagement and disengagement of each of the low speed clutch 71, high speed clutch 72, and medium speed clutch 73 is controlled by the controller 27.
  • the number of clutch discs that the low-speed clutch 71 has is greater than the number of clutch discs that the medium-speed clutch 73 has, and is greater than the number of clutch discs that the high-speed clutch 72 has.
  • the number of clutch disks each of the clutches 71 to 73 has can be changed as appropriate.
  • the low-speed clutch 71 switches between connecting and disconnecting the output shaft 32 and the shaft 55.
  • the high-speed clutch 72 switches between connecting and disconnecting the output shaft 32 and the shaft 55.
  • the medium speed clutch 73 switches connection and disconnection between the output shaft 32 and the third sun gear 63.
  • the medium speed clutch 73 is engaged, the rotation of the third sun gear 63 is transmitted to the output shaft 32 via the medium speed gear 67.
  • the low-speed clutch 71 is an example of a "clutch" according to the present disclosure. The configuration and control of the low speed clutch 71 will be described later.
  • FIG. 3 is a cross-sectional view showing the configuration of the low-speed clutch 71.
  • the low-speed clutch 71 includes a first rotating element 81, a second rotating element 82, a plurality of first clutch discs 83, a plurality of second clutch discs 84, a first return spring 85, a plurality of second A return spring 86 and a piston 87 are provided.
  • the first rotating element 81 faces the second rotating element 82.
  • the first rotating element 81 is separated from the second rotating element 82.
  • the first and second clutch discs 83 and 84 are arranged between the first and second rotating elements 81 and 82.
  • the first and second clutch discs 83, 84 are arranged alternately in a predetermined direction.
  • the first and second clutch discs 83 and 84 are lubricated by transmission oil sealed inside the transmission 22.
  • the first and second clutch discs 83 and 84 are an example of "a plurality of clutch discs" according to the present disclosure.
  • the first clutch disc 83 is supported by the first rotating element 81 and rotates together with the first rotating element 81.
  • the first clutch disc 83 is moved in a predetermined direction by being pressed by the piston 87.
  • the second clutch disc 84 is supported by the second rotating element 82 and rotates together with the second rotating element 82 .
  • the second clutch disc 84 moves in a predetermined direction by being pressed by the first clutch disc 83.
  • the first return spring 85 is held in a compressed state between the first spacer 91 and the second spacer 92.
  • the first return spring 85 urges the second rotational element 82 away from the first rotational element 81 in a predetermined direction.
  • a coil spring can be used as the first return spring 85.
  • the second return spring 86 is arranged between the two first clutch discs 83.
  • the second return spring 86 urges the two first clutch disks 83 to separate from each other in a predetermined direction.
  • a wave spring can be used as the second return spring 86.
  • the piston 87 is in contact with the first clutch disc 83.
  • the piston 87 is movable in a predetermined direction depending on the hydraulic pressure of transmission oil supplied to the oil chamber 88 .
  • the supply oil pressure of transmission oil is controlled by a controller 27.
  • FIG. 4 is a graph showing the relationship between the position of the piston 87 and the supplied oil pressure.
  • the pressing force of the piston 87 is smaller than the urging force of the second return spring 86.
  • the piston 87 is located at the "first position".
  • the first position is a position where the stroke of the piston 87 is "0".
  • Each clutch disc 83, 84 is maintained at an "initial position”.
  • the initial position is a position where each clutch disc 83, 84 is maintained in a disengaged state and is not pressed by piston 87.
  • the piston 87 In the range of the supplied oil pressure from F2 to F3, the piston 87 is in contact with the first spacer 91, and the pressing force of the piston 87 is smaller than the urging force of the first and second return springs 85 and 86. At this time, the piston 87 is maintained at the "second position" by the biasing forces of the first and second return springs 85 and 86 even if the supplied hydraulic pressure increases.
  • Each clutch disc 83, 84 is maintained in the "standby position” even if the supplied hydraulic pressure increases.
  • the standby position is a position where each clutch disc 83, 84 is maintained in a non-engaged state and the gap between each clutch disc 83, 84 is narrower than the initial position.
  • the "second position" corresponds to the "standby position".
  • each clutch disc 83, 84 is engaged. In this way, when the supplied oil pressure is F4 or higher, each clutch disc 83, 84 is located at the "engaged position".
  • the engagement position is a position within a range where each clutch disc 83, 84 is in an engaged state.
  • each clutch disc 83, 84 is disengaged and the low speed clutch 71 is released, and when the supplied oil pressure is more than F4, each clutch disc 83, 84 is disengaged, and the low speed clutch 71 is released. 84 is in an engaged state, and the low speed clutch 71 is engaged.
  • FIG. 5 is a block diagram showing the configuration of the controller 27.
  • the controller 27 includes a moisture amount detection section 27a and a hydraulic pressure control section 27b.
  • the water content detection section 27a is connected to the water content sensor 80.
  • Moisture sensor 80 detects the amount of moisture mixed in transmission oil sealed inside transmission 22 .
  • a known moisture sensor for example, an optical sensor, a capacitive sensor, or another sensor
  • the moisture sensor 80 can be placed in the transmission oil flow path.
  • the moisture content sensor 80 transmits the detected moisture content to the moisture content detection section 27a.
  • the water content detection unit 27a determines whether the water content detected by the water content sensor 80 is greater than or equal to a predetermined threshold.
  • the predetermined threshold value is set to a certain amount of moisture that may cause deterioration (for example, peeling of the friction material) in each of the clutches 71 to 73.
  • the amount of water detecting section 27a sends a detection signal indicating that water has been mixed into the transmission oil to the hydraulic pressure control section 27b.
  • the detection signal is an example of a "temperature increase request" according to the present disclosure.
  • the hydraulic control section 27b supplies transmission oil to the low-speed clutch 71 in response to the detection signal from the water content detection section 27a. Specifically, the hydraulic control unit 27b moves each clutch disc 83, 84 to the standby position by controlling the supply hydraulic pressure of the transmission oil supplied to the low-speed clutch 71 within a range of F2 or more and F3 or less. .
  • the gap between each clutch disc 83, 84 can be narrowed while maintaining each clutch disc 83, 84 in a disengaged state. Therefore, while suppressing moisture mixed in the transmission oil from infiltrating into the friction material of each clutch disc 83, 84, pressure loss of the transmission oil passing through the gap between each clutch disc 83, 84 is reduced.
  • the temperature of the transmission oil can be raised by increasing the temperature. Therefore, moisture mixed in the transmission oil can be removed in a short time with a simple configuration while suppressing deterioration of each clutch disk 83, 84.
  • the low-speed clutch 71 is the clutch with the largest number of clutch discs among the low-speed clutch 71, the high-speed clutch 72, and the medium-speed clutch 73 in terms of the torque to be transmitted. Therefore, the temperature of the transmission oil can be raised more quickly than when the high-speed clutch 72 or the medium-speed clutch 73 is moved to the standby position.
  • the transmission 22 according to this embodiment is an HMT, it does not include a torque converter, and the temperature of the transmission oil does not easily rise. Therefore, the above-mentioned effect obtained by moving the low-speed clutch 71 to the standby position and raising the temperature of the transmission oil is particularly effective.
  • the moisture content detection unit 27a After transmitting a detection signal to the hydraulic pressure control unit 27b, the moisture content detection unit 27a determines whether the moisture content detected by the moisture content sensor 80 has become less than a predetermined threshold value. When the moisture content becomes less than a predetermined threshold, the moisture content detection unit 27a transmits a stop signal to the hydraulic pressure control unit 27b indicating that the temperature increase of the transmission oil should be stopped.
  • the hydraulic control unit 27b When the hydraulic control unit 27b receives the stop signal from the water content detection unit 27a, it returns the low-speed clutch 71 to the initial position.
  • the work vehicle 1 is a wheel loader, but it may be another type of work vehicle such as a bulldozer, hydraulic excavator, dump truck, or motor grader.
  • the transmission 22 is an HMT, but other types of transmissions such as an HST (hydrostatic transmission), an EMT (electro-mechanical transmission), or a multi-speed transmission including a plurality of gears can be used. It may also be a transmission.
  • HST hydrostatic transmission
  • EMT electro-mechanical transmission
  • multi-speed transmission including a plurality of gears can be used. It may also be a transmission.
  • the hydraulic control section 27b moves the low-speed clutch 71 to the standby position in response to receiving the detection signal from the water content detection section 27a, but the present invention is not limited thereto.
  • the hydraulic control unit 27b may move the low-speed clutch 71 to the standby position in response to receiving an operation signal based on an operator operation.
  • the work vehicle 1 is equipped with an operating member (for example, a switch, a lever, etc.) that is operated by the operator in order to raise the temperature of the transmission oil, and the operating member transmits an operating signal according to the operator's operation to the hydraulic control unit. 27b.
  • the operation signal is an example of a "temperature increase request" according to the present disclosure.
  • the water content detection unit 27a detects water contamination in the transmission oil when the water content detected by the water content sensor 80 exceeds a predetermined threshold value, but this is not limited to this. I can't do it.
  • the water content detection unit 27a may detect water contamination in the transmission oil when the estimated value of the water content calculated using a well-known method becomes equal to or greater than a predetermined threshold value.
  • the controller 27 moves the low-speed clutch 71 to the standby position, but the present invention is not limited thereto.
  • the controller 27 may move at least one clutch included in the transmission to a standby position.
  • the controller 27 may move both one of the high speed clutch 72 and the medium speed clutch 73 and the low speed clutch 71 to the standby position, or may move only one of the high speed clutch 72 and the medium speed clutch 73. It may be moved to the standby position, or all of the clutches 71 to 73 may be moved to the standby position.
  • the clutch to be moved to the standby position may be another clutch (for example, a forward clutch, a reverse clutch, etc.).
  • the standby position of the low-speed clutch 71 can be set at any position between the initial position and the engaged position of each clutch disc 83, 84.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Hydraulic Clutches, Magnetic Clutches, Fluid Clutches, And Fluid Joints (AREA)

Abstract

A work vehicle (1) comprises a low-speed clutch (71) which includes first and second clutch disks (83, 84) lubricated by transmission oil and a controller (27) which controls engagement and release of the low-speed clutch (71). The controller (27) moves the first and second clutch disks (83, 84) to a standby position between an initial position and an engagement position in response to a detection signal indicating detection of mixture of water with the transmission oil.

Description

作業車両及び作業車両の制御方法Work vehicle and work vehicle control method
　本開示は、作業車両及び作業車両の制御方法に関する。 The present disclosure relates to a work vehicle and a method of controlling the work vehicle.
　特許文献１には、作業車両の起動時に、トランスミッションにおけるクラッチの駆動やクラッチディスクの潤滑に用いられるトランスミションオイル（作動油）を昇温させる暖気回路が開示されている。 Patent Document 1 discloses a warm-up circuit that raises the temperature of transmission oil (hydraulic oil) used for driving a clutch in a transmission and lubricating a clutch disk when a work vehicle is started.
国際公開第２０１５／０２５６０２号International Publication No. 2015/025602
　特許文献１に記載の暖気回路によってトランスミションオイルを昇温させるとトランスミションオイルに混入した水分を除去できるため、クラッチディスクが水分によって劣化してしまうことを抑制できる。 When the temperature of the transmission oil is raised using the warm-up circuit described in Patent Document 1, moisture mixed in the transmission oil can be removed, so deterioration of the clutch disc due to moisture can be suppressed.
　しかしながら、トランスミションオイルを昇温するために特許文献１に記載の暖気回路を設けるとトランスミッションの構成が複雑化してしまうため好ましくない。 However, providing the warm-up circuit described in Patent Document 1 to raise the temperature of the transmission oil is not preferable because the configuration of the transmission becomes complicated.
　本開示は、トランスミションオイルに混入した水分を簡素な構成で除去可能な作業車両及び作業車両の制御方法を提供することを目的とする。 An object of the present disclosure is to provide a work vehicle and a method for controlling a work vehicle that can remove water mixed into transmission oil with a simple configuration.
　本開示に係る作業車両は、トランスミションオイルによって潤滑される複数のクラッチディスクを有するクラッチと、クラッチの係合及び解放を制御するコントローラとを備える。コントローラは、トランスミションオイルの昇温要求に応じて、複数のクラッチディスクを初期位置及び係合位置の間の待機位置に移動させる。 A work vehicle according to the present disclosure includes a clutch having a plurality of clutch discs lubricated by transmission oil, and a controller that controls engagement and disengagement of the clutch. The controller moves the plurality of clutch disks to a standby position between an initial position and an engaged position in response to a request for raising the temperature of transmission oil.
　本開示によれば、トランスミションオイルに混入した水分を簡素な構成で除去可能な作業車両及び作業車両の制御方法を提供することができる。 According to the present disclosure, it is possible to provide a work vehicle and a method for controlling a work vehicle that can remove water mixed into transmission oil with a simple configuration.
実施形態に係る作業車両の側面図Side view of the work vehicle according to the embodiment 実施形態に係るトランスミッションのスケルトン図Skeleton diagram of a transmission according to an embodiment 実施形態に係る中速クラッチの構成を示す断面図A cross-sectional view showing the configuration of a medium-speed clutch according to an embodiment. 実施形態に係るピストンの位置と供給油圧との関係を示すグラフGraph showing the relationship between piston position and supply oil pressure according to the embodiment 実施形態に係るコントローラの構成を示すブロック図Block diagram showing the configuration of a controller according to an embodiment
　（作業車両１）
　図１は、実施形態に係る作業車両１の側面図である。作業車両１は、ホイールローダである。図１に示すように、作業車両１は、車体２及び作業機３を備える。 (Work vehicle 1)
FIG. 1 is a side view of a work vehicle 1 according to the embodiment. Work vehicle 1 is a wheel loader. As shown in FIG. 1, a work vehicle 1 includes a vehicle body 2 and a work machine 3.
　車体２は、前車体２ａ及び後車体２ｂを含む。後車体２ｂは、前車体２ａに対して左右に揺動可能に接続される。前車体２ａ及び後車体２ｂには、油圧シリンダ１５が連結される。油圧シリンダ１５が伸縮することによって、前車体２ａが後車体２ｂに対して左右に揺動する。 The vehicle body 2 includes a front vehicle body 2a and a rear vehicle body 2b. The rear vehicle body 2b is connected to the front vehicle body 2a so as to be swingable from side to side. A hydraulic cylinder 15 is connected to the front vehicle body 2a and the rear vehicle body 2b. As the hydraulic cylinder 15 expands and contracts, the front vehicle body 2a swings left and right with respect to the rear vehicle body 2b.
　作業機３は、掘削等の作業に用いられる。作業機３は、前車体２ａに取り付けられる。作業機３は、ブーム１１、バケット１２、及び油圧シリンダ１３，１４を含む。油圧シリンダ１３，１４が伸縮することによって、ブーム１１及びバケット１２が動作する。 The work machine 3 is used for work such as excavation. The working machine 3 is attached to the front vehicle body 2a. The work machine 3 includes a boom 11, a bucket 12, and hydraulic cylinders 13 and 14. The boom 11 and bucket 12 operate as the hydraulic cylinders 13 and 14 expand and contract.
　作業車両１は、エンジン２１、トランスミッション２２、及び走行装置２３を備える。エンジン２１は、例えばディーゼルエンジンなどの内燃機関である。トランスミッション２２は、エンジン２１に接続される。トランスミッション２２の内部にはトランスミションオイルが封入されている。トランスミッション２２の構成については後述する。 The work vehicle 1 includes an engine 21, a transmission 22, and a traveling device 23. Engine 21 is, for example, an internal combustion engine such as a diesel engine. Transmission 22 is connected to engine 21 . Transmission oil is sealed inside the transmission 22. The configuration of the transmission 22 will be described later.
　走行装置２３は、作業車両１を走行させる。走行装置２３は、前輪２４及び後輪２５を有する。前輪２４は、前車体２ａに設けられる。後輪２５は、後車体２ｂに設けられる。前輪２４及び後輪２５は、図示しないアクスルを介してトランスミッション２２に接続される。 The traveling device 23 causes the work vehicle 1 to travel. The traveling device 23 has front wheels 24 and rear wheels 25. The front wheels 24 are provided on the front vehicle body 2a. The rear wheel 25 is provided on the rear vehicle body 2b. The front wheels 24 and the rear wheels 25 are connected to the transmission 22 via an axle (not shown).
　作業車両１は、図示しない油圧ポンプを備える。油圧ポンプは、エンジン２１に接続される。油圧ポンプは、エンジン２１によって駆動され、トランスミションオイルを吐出する。油圧ポンプから吐出されたトランスミションオイルは、トランスミッション２２に供給される。トランスミションオイルは、トランスミッション２２が備える各クラッチ（後述する低速クラッチ７１、高速クラッチ７２、及び中速クラッチ７３）の駆動と、各クラッチが有するクラッチディスクの潤滑との両方に利用される。 The work vehicle 1 is equipped with a hydraulic pump (not shown). A hydraulic pump is connected to the engine 21. The hydraulic pump is driven by the engine 21 and discharges transmission oil. Transmission oil discharged from the hydraulic pump is supplied to the transmission 22. The transmission oil is used both to drive each clutch (a low-speed clutch 71, a high-speed clutch 72, and a medium-speed clutch 73, which will be described later) included in the transmission 22, and to lubricate a clutch disk included in each clutch.
　作業車両１は、コントローラ２７を備える。コントローラ２７は、例えばプロセッサ及びメモリなどを有する。コントローラ２７は、エンジン２１及びトランスミッション２２を制御する。コントローラ２７の機能については後述する。 The work vehicle 1 includes a controller 27. The controller 27 includes, for example, a processor and a memory. Controller 27 controls engine 21 and transmission 22. The functions of the controller 27 will be described later.
　（トランスミッション２２）
　図２は、トランスミッション２２の構成を示すスケルトン図である。トランスミッション２２は、いわゆるＨＭＴ（油圧－機械式変速装置）である。 (Transmission 22)
FIG. 2 is a skeleton diagram showing the configuration of the transmission 22. As shown in FIG. The transmission 22 is a so-called HMT (hydraulic-mechanical transmission).
　図２に示すように、トランスミッション２２は、入力軸３１、出力軸３２、第１遊星歯車機構３３、第２遊星歯車機構３４、第３遊星歯車機構３５、第１可変装置３６、及び第２可変装置３７を備える。 As shown in FIG. 2, the transmission 22 includes an input shaft 31, an output shaft 32, a first planetary gear mechanism 33, a second planetary gear mechanism 34, a third planetary gear mechanism 35, a first variable device 36, and a second variable A device 37 is provided.
　入力軸３１は、エンジン２１に接続される。出力軸３２は、走行装置２３に接続される。第１遊星歯車機構３３、第２遊星歯車機構３４、及び第３遊星歯車機構３５は、同軸に配置される。入力軸３１及び出力軸３２それぞれは、第１遊星歯車機構３３、第２遊星歯車機構３４、及び第３遊星歯車機構３５の中心軸Ｃ１から偏心して配置される。 The input shaft 31 is connected to the engine 21. The output shaft 32 is connected to the traveling device 23. The first planetary gear mechanism 33, the second planetary gear mechanism 34, and the third planetary gear mechanism 35 are arranged coaxially. The input shaft 31 and the output shaft 32 are arranged eccentrically from the central axis C1 of the first planetary gear mechanism 33, the second planetary gear mechanism 34, and the third planetary gear mechanism 35, respectively.
　第１遊星歯車機構３３は、第１キャリア４１、複数の第１プラネタリギア４２、第１サンギア４３、及び第１リングギア４４を有する。入力軸３１には、入力ギア４５が嵌合される。第１キャリア４１は、外歯式のギア４６を含む。ギア４６と入力ギア４５が噛み合うことにより、第１キャリア４１は入力軸３１に接続される。第１プラネタリギア４２は、第１キャリア４１に連結されており、第１キャリア４１とともに中心軸Ｃ１回りに回転可能である。第１サンギア４３は、シャフト５５に嵌合されており、シャフト５５と一体的に回転可能である。第１サンギア４３は、第１プラネタリギア４２と噛み合う。第１リングギア４４は、第１プラネタリギア４２と噛み合う。 The first planetary gear mechanism 33 includes a first carrier 41 , a plurality of first planetary gears 42 , a first sun gear 43 , and a first ring gear 44 . An input gear 45 is fitted onto the input shaft 31 . The first carrier 41 includes an external gear 46 . By meshing the gear 46 and the input gear 45, the first carrier 41 is connected to the input shaft 31. The first planetary gear 42 is connected to the first carrier 41 and is rotatable together with the first carrier 41 around the central axis C1. The first sun gear 43 is fitted onto the shaft 55 and can rotate integrally with the shaft 55. The first sun gear 43 meshes with the first planetary gear 42. The first ring gear 44 meshes with the first planetary gear 42.
　第２遊星歯車機構３４は、第２サンギア５１、複数の第２プラネタリギア５２、第２キャリア５３、及び第２リングギア５４を有する。第２サンギア５１は、第１キャリア４１に連結されており、第１キャリア４１とともに中心軸Ｃ１回りに回転可能である。第２サンギア５１は、シャフト５５周りを空転可能である。第２プラネタリギア５２は、第２サンギア５１と噛み合う。第２キャリア５３は、第２プラネタリギア５２に連結されており、第２プラネタリギア５２とともに中心軸Ｃ１回りに回転可能である。第２リングギア５４は、第２プラネタリギア５２と噛み合う。 The second planetary gear mechanism 34 includes a second sun gear 51, a plurality of second planetary gears 52, a second carrier 53, and a second ring gear 54. The second sun gear 51 is connected to the first carrier 41 and is rotatable together with the first carrier 41 around the central axis C1. The second sun gear 51 can idle around the shaft 55. The second planetary gear 52 meshes with the second sun gear 51. The second carrier 53 is connected to the second planetary gear 52 and is rotatable together with the second planetary gear 52 around the central axis C1. The second ring gear 54 meshes with the second planetary gear 52.
　第２リングギア５４は、第１リングギア４４に接続される。第１リングギア４４及び第２リングギア５４は、一体的に形成されており、リング部材４７を構成する。リング部材４７の外周面は、外歯式のギア４８を含む。ギア４８は、第１可変装置３６に接続される。 The second ring gear 54 is connected to the first ring gear 44. The first ring gear 44 and the second ring gear 54 are integrally formed and constitute a ring member 47. The outer peripheral surface of the ring member 47 includes an external gear 48 . Gear 48 is connected to first variable device 36 .
　第１可変装置３６は、油圧式のポンプ／モータである。第１可変装置３６の容量は、コントローラ２７によって制御される。コントローラ２７は、第１可変装置３６の回転速度を制御することによって、入力軸３１に対する出力軸３２の速度比を無段変速させる。第１可変装置３６の回転軸には、ギア４９が嵌合される。ギア４９は、上述のギア４８と噛み合う。 The first variable device 36 is a hydraulic pump/motor. The capacity of the first variable device 36 is controlled by the controller 27. The controller 27 continuously changes the speed ratio of the output shaft 32 to the input shaft 31 by controlling the rotational speed of the first variable device 36 . A gear 49 is fitted onto the rotating shaft of the first variable device 36 . Gear 49 meshes with gear 48 described above.
　第３遊星歯車機構３５は、第３キャリア６１、複数の第３プラネタリギア６２、第３サンギア６３、及び第３リングギア６４を有する。第３キャリア６１は、第２キャリア５３に接続されており、第２キャリア５３とともに中心軸Ｃ１回りに回転可能である。第３キャリア６１は、第２キャリア５３と一体でも別体でもよい。第３プラネタリギア６２は、第３キャリア６１に連結されており、第３キャリア６１とともに中心軸Ｃ１回りに回転可能である。 The third planetary gear mechanism 35 includes a third carrier 61, a plurality of third planetary gears 62, a third sun gear 63, and a third ring gear 64. The third carrier 61 is connected to the second carrier 53 and is rotatable together with the second carrier 53 around the central axis C1. The third carrier 61 may be integrated with the second carrier 53 or may be separate. The third planetary gear 62 is connected to the third carrier 61 and is rotatable together with the third carrier 61 around the central axis C1.
　第３サンギア６３は、第３プラネタリギア６２と噛み合う。第３サンギア６３は、シャフト５５周りを空転可能である。第３リングギア６４は、第３プラネタリギア６２と噛み合う。第３リングギア６４は、回転不能である。第３リングギア６４は、例えばトランスミッション２２のハウジングに固定される。第３遊星歯車機構３５は、第２遊星歯車機構３４からの回転を増速して出力する。 The third sun gear 63 meshes with the third planetary gear 62. The third sun gear 63 can idle around the shaft 55. The third ring gear 64 meshes with the third planetary gear 62. Third ring gear 64 is non-rotatable. The third ring gear 64 is fixed to the housing of the transmission 22, for example. The third planetary gear mechanism 35 accelerates the rotation from the second planetary gear mechanism 34 and outputs it.
　第２可変装置３７は、油圧式のポンプ／モータである。第２可変装置３７は、第１可変装置３６と図示しない油圧回路によって接続されている。第１可変装置３６がポンプとして機能してトランスミションオイルを吐出する場合、第２可変装置３７はモータとして機能して第１可変装置３６からのトランスミションオイルによって駆動される。第２可変装置３７がポンプとして機能してトランスミションオイルを吐出する場合、第１可変装置３６はモータとして機能して第２可変装置３７からのトランスミションオイルによって駆動される。 The second variable device 37 is a hydraulic pump/motor. The second variable device 37 is connected to the first variable device 36 by a hydraulic circuit (not shown). When the first variable device 36 functions as a pump and discharges transmission oil, the second variable device 37 functions as a motor and is driven by the transmission oil from the first variable device 36. When the second variable device 37 functions as a pump and discharges transmission oil, the first variable device 36 functions as a motor and is driven by the transmission oil from the second variable device 37.
　第２可変装置３７の容量は、コントローラ２７によって制御される。コントローラ２７は、第２可変装置３７の回転速度を制御することによって、速度比を無段変速させる。第２可変装置３７は、第２遊星歯車機構３４と同軸に配置される。 The capacity of the second variable device 37 is controlled by the controller 27. The controller 27 continuously changes the speed ratio by controlling the rotational speed of the second variable device 37. The second variable device 37 is arranged coaxially with the second planetary gear mechanism 34 .
　第２可変装置３７の回転軸には、シャフト５５が接続される。シャフト５５には、第１サンギア４３が嵌合される。シャフト５５は、第１サンギア４３及び第２可変装置３７を連結する。シャフト５５は、第１乃至第３遊星歯車機構３３～３５と同軸に配置される。 A shaft 55 is connected to the rotation axis of the second variable device 37. The first sun gear 43 is fitted onto the shaft 55 . Shaft 55 connects first sun gear 43 and second variable device 37 . The shaft 55 is arranged coaxially with the first to third planetary gear mechanisms 33 to 35.
　トランスミッション２２は、低速ギア６５、高速ギア６６、中速ギア６７、低速クラッチ７１、高速クラッチ７２、及び中速クラッチ７３を備える。低速ギア６５、高速ギア６６、及び中速ギア６７は、第１乃至第３遊星歯車機構３３～３５と同軸に配置される。低速ギア６５は、シャフト５５に嵌合されており、シャフト５５とともに中心軸Ｃ１回りに回転可能である。低速ギア６５は、低速クラッチ７１を介して出力軸３２に接続される。 The transmission 22 includes a low speed gear 65, a high speed gear 66, a medium speed gear 67, a low speed clutch 71, a high speed clutch 72, and a medium speed clutch 73. The low speed gear 65, high speed gear 66, and medium speed gear 67 are arranged coaxially with the first to third planetary gear mechanisms 33 to 35. The low-speed gear 65 is fitted onto the shaft 55 and is rotatable together with the shaft 55 around the central axis C1. Low speed gear 65 is connected to output shaft 32 via low speed clutch 71.
　高速ギア６６は、高速クラッチ７２を介してシャフト５５に接続される。高速クラッチ７２が係合されると、高速ギア６６はシャフト５５とともに回転可能である。高速ギア６６は、出力軸３２に接続される。中速ギア６７は、第３サンギア６３に接続されており、第３サンギア６３とともに中心軸Ｃ１回りに回転可能である。中速ギア６７は、第３サンギア６３と一体でも別体でもよい。 The high-speed gear 66 is connected to the shaft 55 via a high-speed clutch 72. When high speed clutch 72 is engaged, high speed gear 66 is rotatable with shaft 55 . High speed gear 66 is connected to output shaft 32 . The medium speed gear 67 is connected to the third sun gear 63 and can rotate together with the third sun gear 63 around the central axis C1. The medium speed gear 67 may be integrated with the third sun gear 63 or may be separate from the third sun gear 63.
　低速クラッチ７１、高速クラッチ７２、及び中速クラッチ７３それぞれは、複数のクラッチディスクを有する油圧式の湿式多板クラッチである。低速クラッチ７１、高速クラッチ７２、及び中速クラッチ７３それぞれの係合及び解放は、コントローラ２７によって制御される。 Each of the low-speed clutch 71, high-speed clutch 72, and medium-speed clutch 73 is a hydraulic wet multi-disc clutch having a plurality of clutch discs. The engagement and disengagement of each of the low speed clutch 71, high speed clutch 72, and medium speed clutch 73 is controlled by the controller 27.
　本実施形態において、低速クラッチ７１が有するクラッチディスクの枚数は、中速クラッチ７３が有するクラッチディスクの枚数より多く、高速クラッチ７２が有するクラッチディスクの枚数より多いものとする。ただし、各クラッチ７１～７３それぞれが有するクラッチディスクの枚数は適宜変更可能である。 In this embodiment, the number of clutch discs that the low-speed clutch 71 has is greater than the number of clutch discs that the medium-speed clutch 73 has, and is greater than the number of clutch discs that the high-speed clutch 72 has. However, the number of clutch disks each of the clutches 71 to 73 has can be changed as appropriate.
　低速クラッチ７１は、出力軸３２とシャフト５５との連結及び遮断を切り換える。低速クラッチ７１が係合されると、低速ギア６５を介して、シャフト５５の回転が出力軸３２に伝達される。高速クラッチ７２は、出力軸３２とシャフト５５との連結及び遮断を切り換える。高速クラッチ７２が係合されると、シャフト５５の回転が出力軸３２に伝達される。中速クラッチ７３は、出力軸３２と第３サンギア６３との連結及び遮断を切り換える。中速クラッチ７３が係合されると、中速ギア６７を介して、第３サンギア６３の回転が出力軸３２に伝達される。本実施形態において、低速クラッチ７１は、本開示に係る「クラッチ」の一例である。低速クラッチ７１の構成及び制御については後述する。 The low-speed clutch 71 switches between connecting and disconnecting the output shaft 32 and the shaft 55. When the low-speed clutch 71 is engaged, the rotation of the shaft 55 is transmitted to the output shaft 32 via the low-speed gear 65. The high-speed clutch 72 switches between connecting and disconnecting the output shaft 32 and the shaft 55. When the high-speed clutch 72 is engaged, the rotation of the shaft 55 is transmitted to the output shaft 32. The medium speed clutch 73 switches connection and disconnection between the output shaft 32 and the third sun gear 63. When the medium speed clutch 73 is engaged, the rotation of the third sun gear 63 is transmitted to the output shaft 32 via the medium speed gear 67. In this embodiment, the low-speed clutch 71 is an example of a "clutch" according to the present disclosure. The configuration and control of the low speed clutch 71 will be described later.
　なお、図２では、低速クラッチ７１、高速クラッチ７２、及び中速クラッチ７３それぞれと出力軸３２との間の構成の一部が省略されている。低速クラッチ７１、高速クラッチ７２、及び中速クラッチ７３それぞれと出力軸３２との間には、他のクラッチやギア（例えば、前進ギア、後進ギアなど）が配置されていてもよい。 Note that in FIG. 2, a part of the structure between each of the low-speed clutch 71, high-speed clutch 72, and medium-speed clutch 73 and the output shaft 32 is omitted. Other clutches or gears (for example, forward gear, reverse gear, etc.) may be arranged between each of the low speed clutch 71, high speed clutch 72, and medium speed clutch 73 and the output shaft 32.
　（低速クラッチ７１）
　図３は、低速クラッチ７１の構成を示す断面図である。図３に示すように、低速クラッチ７１は、第１回転要素８１、第２回転要素８２、複数の第１クラッチディスク８３、複数の第２クラッチディスク８４、第１戻しバネ８５、複数の第２戻しバネ８６、及びピストン８７を備える。 (Low speed clutch 71)
FIG. 3 is a cross-sectional view showing the configuration of the low-speed clutch 71. As shown in FIG. 3, the low-speed clutch 71 includes a first rotating element 81, a second rotating element 82, a plurality of first clutch discs 83, a plurality of second clutch discs 84, a first return spring 85, a plurality of second A return spring 86 and a piston 87 are provided.
　第１回転要素８１は、第２回転要素８２と対向する。第１回転要素８１は、第２回転要素８２から離れている。 The first rotating element 81 faces the second rotating element 82. The first rotating element 81 is separated from the second rotating element 82.
　第１及び第２クラッチディスク８３，８４は、第１及び第２回転要素８１，８２の間に配置される。第１及び第２クラッチディスク８３，８４は、所定方向において交互に配置される。第１及び第２クラッチディスク８３，８４は、トランスミッション２２の内部に封入されたトランスミションオイルによって潤滑される。本実施形態において、第１及び第２クラッチディスク８３，８４は、本開示に係る「複数のクラッチディスク」の一例である。 The first and second clutch discs 83 and 84 are arranged between the first and second rotating elements 81 and 82. The first and second clutch discs 83, 84 are arranged alternately in a predetermined direction. The first and second clutch discs 83 and 84 are lubricated by transmission oil sealed inside the transmission 22. In this embodiment, the first and second clutch discs 83 and 84 are an example of "a plurality of clutch discs" according to the present disclosure.
　第１クラッチディスク８３は、第１回転要素８１に支持されており、第１回転要素８１とともに回転する。第１クラッチディスク８３は、ピストン８７に押圧されることによって所定方向に移動する。第２クラッチディスク８４は、第２回転要素８２に支持されており、第２回転要素８２とともに回転する。第２クラッチディスク８４は、第１クラッチディスク８３に押圧されることによって所定方向に移動する。 The first clutch disc 83 is supported by the first rotating element 81 and rotates together with the first rotating element 81. The first clutch disc 83 is moved in a predetermined direction by being pressed by the piston 87. The second clutch disc 84 is supported by the second rotating element 82 and rotates together with the second rotating element 82 . The second clutch disc 84 moves in a predetermined direction by being pressed by the first clutch disc 83.
　第１戻しバネ８５は、第１のスペーサ９１及び第２のスペーサ９２の間に圧縮された状態で保持される。第１戻しバネ８５は、所定方向において第１回転要素８１から離れる向きに第２回転要素８２を付勢する。第１戻しバネ８５としては、例えばコイルスプリングを用いることができる。 The first return spring 85 is held in a compressed state between the first spacer 91 and the second spacer 92. The first return spring 85 urges the second rotational element 82 away from the first rotational element 81 in a predetermined direction. As the first return spring 85, for example, a coil spring can be used.
　第２戻しバネ８６は、２枚の第１クラッチディスク８３の間に配置される。第２戻しバネ８６は、所定方向において２枚の第１クラッチディスク８３どうしが離れるよう付勢する。第２戻しバネ８６としては、例えばウェーブスプリングを用いることができる。 The second return spring 86 is arranged between the two first clutch discs 83. The second return spring 86 urges the two first clutch disks 83 to separate from each other in a predetermined direction. As the second return spring 86, for example, a wave spring can be used.
　ピストン８７は、第１クラッチディスク８３に接触している。ピストン８７は、油室８８に供給されるトランスミションオイルの供給油圧に応じて、所定方向に移動可能である。トランスミションオイルの供給油圧は、コントローラ２７によって制御される。 The piston 87 is in contact with the first clutch disc 83. The piston 87 is movable in a predetermined direction depending on the hydraulic pressure of transmission oil supplied to the oil chamber 88 . The supply oil pressure of transmission oil is controlled by a controller 27.
　ここで、図４は、ピストン８７の位置と供給油圧との関係を示すグラフである。 Here, FIG. 4 is a graph showing the relationship between the position of the piston 87 and the supplied oil pressure.
　供給油圧が０以上Ｆ１以下の範囲において、ピストン８７の押圧力は第２戻しバネ８６の付勢力より小さい。このとき、ピストン８７は「第１位置」に位置する。第１位置とは、ピストン８７のストロークが“０”の位置である。各クラッチディスク８３，８４は、「初期位置」に維持される。初期位置とは、各クラッチディスク８３，８４が非係合状態に維持され、かつ、ピストン８７によって押圧もされない位置である。 In the range where the supplied oil pressure is 0 or more and F1 or less, the pressing force of the piston 87 is smaller than the urging force of the second return spring 86. At this time, the piston 87 is located at the "first position". The first position is a position where the stroke of the piston 87 is "0". Each clutch disc 83, 84 is maintained at an "initial position". The initial position is a position where each clutch disc 83, 84 is maintained in a disengaged state and is not pressed by piston 87.
　供給油圧がＦ１超Ｆ２未満の範囲において、ピストン８７は第１のスペーサ９１から離れており、かつ、ピストン８７の押圧力は第２戻しバネ８６の付勢力より大きい。このとき、ピストン８７は、供給油圧の増大に伴い、第２戻しバネ８６の付勢力に抗して所定方向に移動する。供給油圧が増大しても各クラッチディスク８３，８４は非係合状態に維持されるが、供給油圧の増大に伴って各クラッチディスク８３，８４どうしの隙間は初期位置に比べて徐々に狭くなる。 In a range where the supplied oil pressure is more than F1 and less than F2, the piston 87 is separated from the first spacer 91, and the pressing force of the piston 87 is greater than the urging force of the second return spring 86. At this time, the piston 87 moves in a predetermined direction against the biasing force of the second return spring 86 as the supplied hydraulic pressure increases. Even if the supplied hydraulic pressure increases, each clutch disc 83, 84 is maintained in a disengaged state, but as the supplied hydraulic pressure increases, the gap between each clutch disc 83, 84 gradually narrows compared to the initial position. .
　供給油圧がＦ２以上Ｆ３以下の範囲において、ピストン８７は第１のスペーサ９１に当接しており、かつ、ピストン８７の押圧力は第１及び第２戻しバネ８５，８６の付勢力より小さい。このとき、ピストン８７は、供給油圧が増大しても、第１及び第２戻しバネ８５，８６の付勢力によって「第２位置」に維持される。各クラッチディスク８３，８４は、供給油圧が増大しても、「待機位置」に維持される。待機位置とは、各クラッチディスク８３，８４が非係合状態に維持され、かつ、各クラッチディスク８３，８４どうしの隙間が初期位置より狭い位置である。「第２位置」は「待機位置」に相当する。 In the range of the supplied oil pressure from F2 to F3, the piston 87 is in contact with the first spacer 91, and the pressing force of the piston 87 is smaller than the urging force of the first and second return springs 85 and 86. At this time, the piston 87 is maintained at the "second position" by the biasing forces of the first and second return springs 85 and 86 even if the supplied hydraulic pressure increases. Each clutch disc 83, 84 is maintained in the "standby position" even if the supplied hydraulic pressure increases. The standby position is a position where each clutch disc 83, 84 is maintained in a non-engaged state and the gap between each clutch disc 83, 84 is narrower than the initial position. The "second position" corresponds to the "standby position".
　供給油圧がＦ３超Ｆ４以下の範囲において、ピストン８７の押圧力は第１及び第２戻しバネ８５，８６の付勢力より大きい。このとき、ピストン８７は、供給油圧の増大に伴い、第１及び第２戻しバネ８５，８６の付勢力に抗して「第３位置」まで移動する。そして、供給油圧がＦ４に達したとき、各クラッチディスク８３，８４は係合される。このように、供給油圧がＦ４以上であると、各クラッチディスク８３，８４は「係合位置」に位置する。係合位置とは、各クラッチディスク８３，８４が係合状態となる範囲内の位置である。 In the range where the supplied oil pressure is above F3 and below F4, the pressing force of the piston 87 is greater than the urging force of the first and second return springs 85 and 86. At this time, the piston 87 moves to the "third position" against the biasing forces of the first and second return springs 85 and 86 as the supplied hydraulic pressure increases. Then, when the supplied hydraulic pressure reaches F4, each clutch disc 83, 84 is engaged. In this way, when the supplied oil pressure is F4 or higher, each clutch disc 83, 84 is located at the "engaged position". The engagement position is a position within a range where each clutch disc 83, 84 is in an engaged state.
　以上の通り、供給油圧が０以上Ｆ４未満である場合、各クラッチディスク８３，８４が非係合状態となって低速クラッチ７１は解放され、供給油圧がＦ４以上である場合、各クラッチディスク８３，８４は係合状態となって低速クラッチ７１は係合される。 As mentioned above, when the supplied oil pressure is 0 or more and less than F4, each clutch disc 83, 84 is disengaged and the low speed clutch 71 is released, and when the supplied oil pressure is more than F4, each clutch disc 83, 84 is disengaged, and the low speed clutch 71 is released. 84 is in an engaged state, and the low speed clutch 71 is engaged.
　（コントローラ２７）
　図５は、コントローラ２７の構成を示すブロック図である。コントローラ２７は、水分量検出部２７ａ及び油圧制御部２７ｂを備える。 (controller 27)
FIG. 5 is a block diagram showing the configuration of the controller 27. The controller 27 includes a moisture amount detection section 27a and a hydraulic pressure control section 27b.
　水分量検出部２７ａは、水分量センサ８０に接続される。水分量センサ８０は、トランスミッション２２の内部に封入されたトランスミションオイルに混入している水分量を検出する。水分量センサ８０としては、既知の水分量センサ（例えば、光学式のセンサ、静電容量式のセンサ、或いはその他のセンサ）を用いることができる。水分量センサ８０は、トランスミションオイルの流路に配置することができる。水分量センサ８０は、検出した水分量を水分量検出部２７ａに送信する。 The water content detection section 27a is connected to the water content sensor 80. Moisture sensor 80 detects the amount of moisture mixed in transmission oil sealed inside transmission 22 . As the moisture sensor 80, a known moisture sensor (for example, an optical sensor, a capacitive sensor, or another sensor) can be used. The moisture sensor 80 can be placed in the transmission oil flow path. The moisture content sensor 80 transmits the detected moisture content to the moisture content detection section 27a.
　水分量検出部２７ａは、水分量センサ８０によって検出された水分量が所定の閾値以上であるか否かを判定する。所定の閾値は、各クラッチ７１～７３に劣化（例えば、摩擦材の剥離など）が生じるおそれのある程度の水分量に設定される。水分量が所定の閾値以上になった場合、水分量検出部２７ａは、トランスミションオイルへの水分混入が検出されたことを示す検出信号を油圧制御部２７ｂに送信する。当該検出信号は、本開示に係る「昇温要求」の一例である。 The water content detection unit 27a determines whether the water content detected by the water content sensor 80 is greater than or equal to a predetermined threshold. The predetermined threshold value is set to a certain amount of moisture that may cause deterioration (for example, peeling of the friction material) in each of the clutches 71 to 73. When the amount of water exceeds a predetermined threshold, the amount of water detecting section 27a sends a detection signal indicating that water has been mixed into the transmission oil to the hydraulic pressure control section 27b. The detection signal is an example of a "temperature increase request" according to the present disclosure.
　油圧制御部２７ｂは、水分量検出部２７ａからの検出信号に応じて低速クラッチ７１にトランスミションオイルを供給する。具体的には、油圧制御部２７ｂは、低速クラッチ７１に供給されるトランスミションオイルの供給油圧をＦ２以上Ｆ３以下の範囲内に制御することで、各クラッチディスク８３，８４を待機位置に移動させる。 The hydraulic control section 27b supplies transmission oil to the low-speed clutch 71 in response to the detection signal from the water content detection section 27a. Specifically, the hydraulic control unit 27b moves each clutch disc 83, 84 to the standby position by controlling the supply hydraulic pressure of the transmission oil supplied to the low-speed clutch 71 within a range of F2 or more and F3 or less. .
　これによって、各クラッチディスク８３，８４を非係合状態に維持しながら、各クラッチディスク８３，８４どうしの隙間を狭くすることができる。そのため、トランスミションオイルに混入した水分が各クラッチディスク８３，８４の摩擦材に浸潤することを抑制しながら、各クラッチディスク８３，８４どうしの隙間を通過するトランスミションオイルの圧力損失（ロス）を増大させてトランスミションオイルを昇温することができる。従って、各クラッチディスク８３，８４の劣化を抑制しながら、トランスミションオイルに混入した水分を簡素な構成で短時間に除去することができる。 As a result, the gap between each clutch disc 83, 84 can be narrowed while maintaining each clutch disc 83, 84 in a disengaged state. Therefore, while suppressing moisture mixed in the transmission oil from infiltrating into the friction material of each clutch disc 83, 84, pressure loss of the transmission oil passing through the gap between each clutch disc 83, 84 is reduced. The temperature of the transmission oil can be raised by increasing the temperature. Therefore, moisture mixed in the transmission oil can be removed in a short time with a simple configuration while suppressing deterioration of each clutch disk 83, 84.
　本実施形態において、低速クラッチ７１は、伝達すべきトルクとの関係から、低速クラッチ７１、高速クラッチ７２、及び中速クラッチ７３のうちクラッチディスクの枚数が最も多いクラッチである。そのため、高速クラッチ７２又は中速クラッチ７３を待機位置に移動させる場合に比べて、トランスミションオイルを迅速に昇温することができる。 In the present embodiment, the low-speed clutch 71 is the clutch with the largest number of clutch discs among the low-speed clutch 71, the high-speed clutch 72, and the medium-speed clutch 73 in terms of the torque to be transmitted. Therefore, the temperature of the transmission oil can be raised more quickly than when the high-speed clutch 72 or the medium-speed clutch 73 is moved to the standby position.
　なお、本実施形態に係るトランスミッション２２はＨＭＴであるためトルクコンバータを備えておらず、トランスミションオイルの温度が上がりにくい。そのため、低速クラッチ７１を待機位置に移動させてトランスミションオイルを昇温することで得られる上記効果は特に有効である。 Note that since the transmission 22 according to this embodiment is an HMT, it does not include a torque converter, and the temperature of the transmission oil does not easily rise. Therefore, the above-mentioned effect obtained by moving the low-speed clutch 71 to the standby position and raising the temperature of the transmission oil is particularly effective.
　水分量検出部２７ａは、検出信号を油圧制御部２７ｂに送信した後、水分量センサ８０によって検出される水分量が所定の閾値未満になったか否かを判定する。水分量が所定の閾値未満になった場合、水分量検出部２７ａは、トランスミションオイルの昇温を停止すべきことを示す停止信号を油圧制御部２７ｂに送信する。 After transmitting a detection signal to the hydraulic pressure control unit 27b, the moisture content detection unit 27a determines whether the moisture content detected by the moisture content sensor 80 has become less than a predetermined threshold value. When the moisture content becomes less than a predetermined threshold, the moisture content detection unit 27a transmits a stop signal to the hydraulic pressure control unit 27b indicating that the temperature increase of the transmission oil should be stopped.
　油圧制御部２７ｂは、水分量検出部２７ａから停止信号を受信すると、低速クラッチ７１を初期位置に戻す。 When the hydraulic control unit 27b receives the stop signal from the water content detection unit 27a, it returns the low-speed clutch 71 to the initial position.
　（実施形態の変形例）
　本発明は以上のような実施形態に限定されるものではなく、本発明の範囲を逸脱することなく種々の変形又は修正が可能である。 (Modified example of embodiment)
The present invention is not limited to the embodiments described above, and various changes and modifications can be made without departing from the scope of the present invention.
　［変形例１］
　上記実施形態においては、作業車両１はホイールローダであることとしたが、ブルドーザ、油圧ショベル、ダンプトラック、モーターグレーダなどの他の種類の作業車両であってもよい。 [Modification 1]
In the above embodiment, the work vehicle 1 is a wheel loader, but it may be another type of work vehicle such as a bulldozer, hydraulic excavator, dump truck, or motor grader.
　［変形例２］
　上記実施形態において、トランスミッション２２はＨＭＴであることとしたが、ＨＳＴ（静油圧式変速装置）、ＥＭＴ（電気－機械式変速装置）、複数の変速ギアを含む多段式トランスミッションなどの他の種類のトランスミッションであってもよい。 [Modification 2]
In the embodiments described above, the transmission 22 is an HMT, but other types of transmissions such as an HST (hydrostatic transmission), an EMT (electro-mechanical transmission), or a multi-speed transmission including a plurality of gears can be used. It may also be a transmission.
　［変形例３］
　上記実施形態において、油圧制御部２７ｂは、水分量検出部２７ａから検出信号を受信したことに応じて低速クラッチ７１を待機位置に移動させることとしたが、これに限られない。油圧制御部２７ｂは、オペレータ操作に基づく操作信号を受信したことに応じて、低速クラッチ７１を待機位置に移動させてもよい。この場合、作業車両１は、トランスミションオイルを昇温するためにオペレータが操作する操作部材（例えば、スイッチ、レバーなど）を備えており、操作部材はオペレータ操作に応じた操作信号を油圧制御部２７ｂに送信する。当該操作信号は、本開示に係る「昇温要求」の一例である。 [Modification 3]
In the embodiment described above, the hydraulic control section 27b moves the low-speed clutch 71 to the standby position in response to receiving the detection signal from the water content detection section 27a, but the present invention is not limited thereto. The hydraulic control unit 27b may move the low-speed clutch 71 to the standby position in response to receiving an operation signal based on an operator operation. In this case, the work vehicle 1 is equipped with an operating member (for example, a switch, a lever, etc.) that is operated by the operator in order to raise the temperature of the transmission oil, and the operating member transmits an operating signal according to the operator's operation to the hydraulic control unit. 27b. The operation signal is an example of a "temperature increase request" according to the present disclosure.
　［変形例４］
　上記実施形態において、水分量検出部２７ａは、水分量センサ８０によって検出される水分量が所定の閾値以上になったことをもってトランスミションオイルへの水分混入を検出することとしたが、これに限られない。水分量検出部２７ａは、周知の手法によって演算される水分量の推定値が所定の閾値以上になったことをもってトランスミションオイルへの水分混入を検出してもよい。 [Modification 4]
In the above embodiment, the water content detection unit 27a detects water contamination in the transmission oil when the water content detected by the water content sensor 80 exceeds a predetermined threshold value, but this is not limited to this. I can't do it. The water content detection unit 27a may detect water contamination in the transmission oil when the estimated value of the water content calculated using a well-known method becomes equal to or greater than a predetermined threshold value.
　［変形例５］
　上記実施形態において、コントローラ２７は、低速クラッチ７１を待機位置に移動させることとしたが、これに限られない。コントローラ２７は、トランスミッションが備える少なくとも１つのクラッチを待機位置に移動させればよい。例えば、コントローラ２７は、高速クラッチ７２及び中速クラッチ７３のうちの一方と低速クラッチ７１との両方を待機位置に移動させてもよいし、高速クラッチ７２及び中速クラッチ７３のうちの一方だけを待機位置に移動させてもよいし、各クラッチ７１～７３の全てを待機位置に移動させてもよい。さらに、待機位置に移動させるクラッチは、他のクラッチ（例えば、前進クラッチ、後進クラッチなど）であってもよい。 [Modification 5]
In the embodiment described above, the controller 27 moves the low-speed clutch 71 to the standby position, but the present invention is not limited thereto. The controller 27 may move at least one clutch included in the transmission to a standby position. For example, the controller 27 may move both one of the high speed clutch 72 and the medium speed clutch 73 and the low speed clutch 71 to the standby position, or may move only one of the high speed clutch 72 and the medium speed clutch 73. It may be moved to the standby position, or all of the clutches 71 to 73 may be moved to the standby position. Furthermore, the clutch to be moved to the standby position may be another clutch (for example, a forward clutch, a reverse clutch, etc.).
　［変形例６］
　低速クラッチ７１の待機位置は、各クラッチディスク８３，８４の初期位置及び係合位置の間の任意の位置に設定することができる。 [Modification 6]
The standby position of the low-speed clutch 71 can be set at any position between the initial position and the engaged position of each clutch disc 83, 84.
１　　　作業車両
２　　　車体
２１　　　エンジン
２２　　　トランスミッション
２３　　　走行装置
２７　　　コントローラ
２７ａ　　水分量検出部
２７ｂ　　油圧制御部
７１　　　低速クラッチ
７２　　　高速クラッチ
７３　　　中速クラッチ
８３　　　第１クラッチディスク
８４　　　第２クラッチディスク
８７　　　ピストン 1 Working vehicle 2 Vehicle body 21 Engine 22 Transmission 23 Traveling device 27 Controller 27a Moisture content detection section 27b Hydraulic control section 71 Low speed clutch 72 High speed clutch 73 Medium speed clutch 83 First clutch disc 84 Second clutch disc 87 Piston

Claims (4)

  1. 　トランスミションオイルによって潤滑される複数のクラッチディスクを有するクラッチと、
    　前記クラッチの係合及び解放を制御するコントローラと、
    を備え、
    　前記コントローラは、前記トランスミションオイルの昇温要求に応じて、前記複数のクラッチディスクを初期位置及び係合位置の間の待機位置に移動させる、
    作業車両。
          a clutch having a plurality of clutch discs lubricated by transmission oil;
    a controller that controls engagement and release of the clutch;
    Equipped with
    The controller moves the plurality of clutch discs to a standby position between an initial position and an engaged position in response to a request for temperature increase of the transmission oil.
    work vehicle.
  2. 　前記昇温要求は、前記トランスミションオイルへの水分混入が検出されたことを示す検出信号である、
    請求項１に記載の作業車両。
          The temperature increase request is a detection signal indicating that moisture has been detected in the transmission oil.
    The work vehicle according to claim 1.
  3. 　前記昇温要求は、オペレータ操作に基づく操作信号である、
    請求項１に記載の作業車両。
          The temperature increase request is an operation signal based on an operator operation,
    The work vehicle according to claim 1.
  4. 　クラッチが有する複数のクラッチディスクを潤滑するトランスミションオイルの昇温要求を受信することと、
    　前記複数のクラッチディスクを待機位置に移動させることと、
    を備える作業車両の制御方法。     receiving a request to raise the temperature of transmission oil that lubricates a plurality of clutch discs included in the clutch;
    moving the plurality of clutch discs to a standby position;
    A method of controlling a work vehicle comprising:
PCT/JP2023/006301 2022-04-01 2023-02-21 Work vehicle and method for controlling work vehicle WO2023189023A1 (en)

Applications Claiming Priority (2)

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JP2022-061801 2022-04-01

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008296611A (en) * 2007-05-29 2008-12-11 Toyota Motor Corp Control device for vehicular power transmission apparatus
JP2014152864A (en) * 2013-02-08 2014-08-25 Daimler Ag Initial setting method of mechanical automatic transmission

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008296611A (en) * 2007-05-29 2008-12-11 Toyota Motor Corp Control device for vehicular power transmission apparatus
JP2014152864A (en) * 2013-02-08 2014-08-25 Daimler Ag Initial setting method of mechanical automatic transmission

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