WO2010041479A1

WO2010041479A1 - Hydraulic-mechanical transmission

Info

Publication number: WO2010041479A1
Application number: PCT/JP2009/052142
Authority: WO
Inventors: 康平小倉; 晃史黒田; 幸雄久保田
Original assignee: ヤンマー株式会社
Priority date: 2008-10-10
Filing date: 2009-02-09
Publication date: 2010-04-15
Also published as: JP5547388B2; JP2010091090A

Abstract

Provided is a hydraulic-mechanical transmission in which switching of a clutch can be performed without being affected by the inclination of actual speed change ratio. The hydraulic-mechanical transmission comprises an HST (10) equipped with a hydraulic pump (11) and a hydraulic motor (12), a planetary gear mechanism (20), a clutch (31a) on the low speed side, a clutch (31b) on the high speed side, and a controller (100) for so controlling the actual speed change ratio (R_t) that the ratio becomes a speed change ratio command value (R_o). The controller (100) is equipped with a map (110) indicating a formula for calculating an inclination angle α corresponding to a speed change ratio (R) and is so configured as to be shifted to a control mode for switching a low speed mode (ML) and a high speed mode (MH) when an inclination angle command value α_of after FB reaches a predetermined switching inclination angle α_c.

Description

Hydraulic-mechanical transmission

The present invention relates to a technique of a hydraulic-mechanical transmission, and more particularly to a technique for controlling the operation of the hydraulic-mechanical transmission.

Conventionally, after distributing the power generated by the engine, one power is transmitted to the planetary gear mechanism, and the other power is transmitted to the planetary gear mechanism via a hydraulic continuously variable transmission. A technique of a hydraulic-mechanical transmission that shifts by combining both powers is known (for example, see Patent Document 1).

In the conventional hydraulic-mechanical transmission, the operation timing of the clutch for switching between the low speed mode and the high speed mode is the actual transmission ratio of the hydraulic-mechanical transmission (hereinafter simply referred to as “actual transmission ratio”). Some of them are determined based on the slope of the actual gear ratio.

For example, there is one that transmits a control signal for switching the clutch when the actual gear ratio reaches “switching gear ratio− (inclination of actual gear ratio × clutch boosting time)”. Here, the switching gear ratio is a target value of the gear ratio at which the clutch is switched, and the clutch boosting time is the time required from when the clutch receives the control signal until it actually operates.
By transmitting a control signal for switching the clutch at such timing, the clutch operates when the actual gear ratio reaches the switching gear ratio, and the low speed mode and the high speed mode can be switched smoothly.

However, when a large load is applied to the hydraulic-mechanical transmission, the gradient of the actual transmission ratio decreases as the actual transmission ratio approaches the switching transmission ratio, and the actual transmission ratio becomes “switching transmission ratio− (actual transmission ratio). The inclination of the clutch x the pressure increase time of the clutch) may not be reached. That is, in this case, a control signal for switching the clutch cannot be transmitted, and the clutch cannot be switched normally.
JP 2005-114160 A

As described above, in the conventional hydraulic-mechanical transmission, the clutch switching timing is affected by the gradient of the actual gear ratio, so that the clutch can be switched normally when a large load is applied. It was disadvantageous in that it could not be done.

The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

That is, in the present invention,
A hydraulic continuously variable transmission mechanism in which at least one of a hydraulic pump or a hydraulic motor is a variable displacement type using a movable swash plate;
A planetary gear mechanism that combines and shifts the power from the drive source and the power from the hydraulic motor;
A swash plate control actuator for adjusting the inclination angle of the movable swash plate by hydraulic pressure;
A low speed side clutch that enables connection and disconnection of power between the low speed side output of the planetary gear mechanism and the HMT output shaft;
A high-speed clutch that enables connection and disconnection of power between the high-speed output of the planetary gear mechanism and the HMT output shaft;
A low-speed solenoid valve that operates the low-speed side clutch hydraulically;
A high-speed solenoid valve for hydraulically actuating the high-speed side clutch;
Gear ratio setting means for setting a gear ratio command value which is a target value of the gear ratio;
Gear ratio detecting means for detecting an actual gear ratio;
A control device for controlling operations of the swash plate control actuator, the low speed solenoid valve, and the high speed solenoid valve so that the actual speed ratio becomes the speed ratio command value;
In a hydraulic-mechanical transmission comprising:
The controller is
Comprising a map showing a calculation formula for calculating the tilt angle corresponding to the gear ratio;
A limiting speed ratio command value that changes so as to become the speed ratio command value at a predetermined time change rate is calculated;
Based on the map, a post-FB inclination angle command value that changes at a predetermined rate of time change corresponding to the limited speed ratio command value is calculated,
Controlling the operation of the swash plate control actuator so that the actual tilt angle of the movable swash plate becomes the post-FB tilt angle command value;
When the post-FB tilt angle command value reaches a predetermined switching tilt angle, the mode shifts to a switching control mode for switching between connection and disconnection of the low speed side clutch and the high speed side clutch.

In the present invention,
The controller is
In the switching control mode, it is necessary from the time when the post-FB inclination angle command value reaches the switching inclination angle until the movable swash plate actually operates after the control signal is received by the swash plate control actuator. Only when the actual gear ratio does not reach the gear ratio command value before the operation dead time elapses, the connection between the low speed side clutch and the high speed side clutch is switched.

In the present invention,
The controller is
When switching the connection of the low speed side clutch and the high speed side clutch in the switching control mode, the low speed side clutch and the high speed side clutch are simultaneously operated for a predetermined time.

In the present invention,
The controller is
In the switching control mode for switching from low speed to high speed, when the limited speed ratio command value is smaller than the switching speed ratio corresponding to the speed ratio command value and the switching inclination angle,
After the limit speed ratio command value is increased to the smaller one of the speed ratio command value or the switching speed ratio, the connection between the low speed side clutch and the high speed side clutch is switched.

In the present invention,
The controller is
In the switching control mode for switching from high speed to low speed, when the limiting speed ratio command value is larger than the switching speed ratio corresponding to the speed ratio command value and the switching inclination angle,
After the limiting speed ratio command value is reduced to the larger one of the speed ratio command value or the switching speed ratio, the connection between the low speed side clutch and the high speed side clutch is switched.

The present invention has an effect that the clutch switching timing can be surely performed based on the inclination angle of the movable swash plate without being affected by the inclination of the actual gear ratio.

The side view which showed the whole structure of the working vehicle which comprises HMT. The schematic diagram which similarly showed the structure of HMT. Similarly side sectional drawing. The figure which shows the map which a control apparatus comprises. The figure which shows the mode of a time-dependent change of each parameter in normal control. The figure which shows the mode of a time-dependent change of each parameter in a 1st control aspect. The flowchart which shows a 1st control aspect. The flowchart which shows the process in the low speed mode of a 1st control aspect. The flowchart which similarly shows the process in acceleration 1st transition mode. The flowchart which similarly shows the process in acceleration 2nd transition mode. The figure which shows the mode of the change of each parameter in acceleration 2nd transition mode similarly. The flowchart which similarly shows the process in acceleration 3rd transition mode. The figure which shows the mode of a time-dependent change of each parameter in a 2nd control aspect. The flowchart which shows the process in the acceleration 2nd transition mode of a 2nd control aspect. The figure which shows the mode of the change of each parameter in acceleration 2nd transition mode similarly. The figure which shows the mode of a time-dependent change of each parameter in a 3rd control aspect. The flowchart which shows the process in the acceleration 2nd transition mode of a 3rd control aspect. The figure which shows the mode of the change of each parameter in acceleration 2nd transition mode similarly. The flowchart which shows a 4th control aspect. The figure which shows the mode of a time-dependent change of each parameter in a 4th control aspect. The flowchart which shows the process in the high speed mode of a 4th control aspect. The flowchart which similarly shows the process in the deceleration 1st transition mode. The flowchart which similarly shows the process in the deceleration 2nd transition mode. The figure which similarly shows the mode of a change of each parameter in deceleration 2nd transition mode. The flowchart which similarly shows the process in the deceleration 3rd transition mode.

Explanation of symbols

1 Working vehicle 3 Engine (drive source)
4 Hydraulic-mechanical transmission (HMT)
7c Shift lever (speed ratio setting means)
10 Hydraulic continuously variable transmission (HST)
11 Hydraulic pump 11a Movable swash plate 12 Hydraulic motor 20 Planetary gear mechanism 24 Second transmission shaft (HMT output shaft)
28 Third transmission gear (high speed side output)
29 Carrier (Low speed side output)
31a Low speed side clutch 31b High speed side clutch 60 Control mechanism 100 Control device 101 Swash plate control actuator 102 Low speed solenoid valve 103 High speed solenoid valve 105 Speed detection means (speed ratio detection means)
110 map R speed ratio R _c switch speed ratio R _o gear ratio command value R _ol limit speed ratio command value R _t actual speed ratio T _H operates the dead time T _w simultaneous fitting time alpha tilt angle alpha _c changeover inclination angle alpha _of FB post Inclination angle command value α _t Actual inclination angle

Next, a work vehicle 1 equipped with a hydraulic-mechanical transmission (hereinafter simply referred to as “HMT”) 4 that is an embodiment of the hydraulic-mechanical transmission according to the present invention will be described with reference to FIG. To do.

The work vehicle 1 performs various agricultural work and civil engineering work using a tilling device such as a rotary and a work machine such as a loader. The work vehicle 1 mainly includes a body frame 2, an engine 3, an HMT 4,

front wheels

5 and 5,

rear wheels

6 and 6, a cabin 7, and the like.

The machine body frame 2 is a main structure of the work vehicle 1. The machine body frame 2 is composed of a plurality of plate materials or the like with the longitudinal direction as the front-rear direction.

The engine 3 is a drive source that generates power for driving the work vehicle 1. The engine 3 is provided in the front part of the body frame 2.

The HMT 4 changes the power generated by the engine 3. The HMT 4 is provided at the rear part of the body frame 2.

The

front wheels

5 and 5 are respectively provided on the left and right of the front part of the body frame 2.
The

rear wheels

6 and 6 are provided on the left and right of the rear part (HMT 4) of the body frame 2, respectively.
The

front wheels

5 and 5 and the

rear wheels

6 and 6 are rotationally driven by the power changed by the HMT 4.

Cabin 7 covers the space where the operator gets on. The cabin 7 is provided from the front and rear substantially central part to the rear part of the body frame 2. In the cabin 7, a handle 7a, a seat 7b, a transmission lever 7c, and the like are provided.

The handle 7a is used to steer the work vehicle 1. The handle 7 a is provided at the front part in the cabin 7.
The seat 7b is for an operator to sit on. The seat 7b is provided behind the handle 7a.
The speed change lever 7c sets the traveling speed of the work vehicle 1 by setting the speed change ratio of the HMT 4. The transmission lever 7c is provided on the right side of the seat 7b. The transmission lever 7c is an embodiment of the transmission ratio setting means according to the present invention.

Hereinafter, the configuration of the HMT 4 will be described with reference to FIGS. 2 and 3. The HMT 4 mainly includes a hydraulic continuously variable transmission mechanism (hereinafter simply referred to as “HST”) 10, a planetary gear mechanism 20, an auxiliary transmission mechanism 40, a differential mechanism 50, a control mechanism 60, and the like.

Hereinafter, the configuration of the HST 10 will be described with reference to FIG. The HST 10 mainly includes a hydraulic pump 11, a hydraulic motor 12, and the like.

The hydraulic pump 11 is a variable displacement hydraulic pump configured to change its capacity. The hydraulic pump 11 is driven by a drive shaft 13 that is rotationally driven by the power generated by the engine 3 and pumps hydraulic oil.
The hydraulic pump 11 includes a movable swash plate 11a for changing its capacity. By changing the inclination angle of the movable swash plate 11a, the flow rate of the hydraulic oil pumped from the hydraulic pump 11 can be changed.

The hydraulic motor 12 is a constant capacity hydraulic motor configured so that its capacity cannot be changed. The hydraulic motor 12 is driven in response to the hydraulic oil fed by the hydraulic pump 11. The hydraulic motor 12 includes an output shaft 12a, and the driving force of the hydraulic motor 12 is output via the output shaft 12a.

An operation mode of the HST 10 configured as described above will be described.
The power generated by the engine 3 is output from the drive shaft 13.
The hydraulic pump 11 is driven by the drive shaft 13 and pumps hydraulic oil in an amount corresponding to the inclination angle of the movable swash plate 11 a to the hydraulic motor 12. The hydraulic motor 12 is driven by hydraulic fluid fed by the hydraulic pump 11 and outputs power from the output shaft 12a. Thus, the power of the drive shaft 13 can be shifted and transmitted to the output shaft 12a, and the gear ratio of the power by the HST 10 can be changed by changing the inclination angle of the movable swash plate 11a. .

In this embodiment, the hydraulic pump 11 is a variable displacement type, but the present invention is not limited to this. That is, it is possible to adopt a configuration in which the hydraulic motor 12 is a variable displacement type, or a configuration in which both the hydraulic pump 11 and the hydraulic motor 12 are variable displacement types.

Hereinafter, the configuration of the planetary gear mechanism 20 will be described with reference to FIGS. 2 and 3. The planetary gear mechanism 20 is disposed behind the HST 10. The planetary gear mechanism 20 mainly includes a planetary case 21, a first transmission shaft 22, a first transmission gear 23, a second transmission shaft 24, a sun gear 25, a second transmission gear 26, an internal gear 27, a third transmission gear 28, a carrier. 29,

planetary gears

30 and 30, a mode switching clutch 31, a third transmission shaft 32, a fourth transmission gear 33, a fifth transmission gear 34, a reverse gear 35, a sixth transmission gear 36, a forward / reverse switching clutch 37, and the like. It has.

The planetary case 21 is a box-shaped member that includes various shafts, gears, and the like that constitute the planetary gear mechanism 20. The planetary case 21 is disposed behind the HST 10.

The first transmission shaft 22 is a shaft-like member arranged on the same axis as the drive shaft 13. The first transmission shaft 22 is provided behind the drive shaft 13 so as not to rotate relative to the drive shaft 13. The rear end portion of the first transmission shaft 22 is rotatably supported by the planetary case 21.

The first transmission gear 23 is provided at the front end portion of the first transmission shaft 22 and the rear end portion of the drive shaft 13 so as not to rotate relative to the first transmission shaft 22 and the drive shaft 13. The front end portion of the first transmission shaft 22 is supported by the planetary case 21 via the first transmission gear 23.

The second transmission shaft 24 is a shaft-like member arranged in parallel with the first transmission shaft 22. The front end portion of the second transmission shaft 24 is rotatably supported by the planetary case 21.

The sun gear 25 is provided at the front end portion of the second transmission shaft 24 so as to be rotatable relative to the second transmission shaft 24. The sun gear 25 includes a gear portion 25a having teeth formed on the outer periphery thereof, and a shaft portion 25b extending forward of the gear portion (see FIG. 3).

The second transmission gear 26 is provided on the shaft 25b of the sun gear 25 so as not to rotate relative to the sun gear 25. The second transmission gear 26 meshes with the first transmission gear 23.

The internal gear 27 is provided on the shaft portion 25b of the sun gear 25 and behind the second transmission gear 26 so as to be rotatable relative to the sun gear 25. The front end portion of the internal gear 27 is provided with a gear portion 27a having teeth formed on the outer periphery thereof. The rear end portion of the internal gear 27 is provided with a gear portion 27b having teeth formed on the inner periphery thereof (see FIG. 3).

The third transmission gear 28 is provided on the second transmission shaft 24 and in front of the sun gear 25 so as to be rotatable relative to the second transmission shaft 24. The front end portion of the third transmission gear 28 is provided with a gear portion 28a having teeth formed on the outer periphery thereof (see FIG. 3). The third transmission gear 28 is an embodiment of the high speed side output of the planetary gear mechanism according to the present invention.

The carrier 29 is provided on the second transmission shaft 24 and in front of the third transmission gear 28 so as to be rotatable relative to the second transmission shaft 24. The rear end portion of the carrier 29 is provided with a gear portion 29a having teeth formed on the outer periphery thereof (see FIG. 3). The carrier 29 is one embodiment of the low speed side output of the planetary gear mechanism according to the present invention.

The planetary gears 30... Are rotatably supported on the front end portion of the carrier 29 via the

planetary shafts

30 a, 30 a. A plurality of

planetary gears

30, 30... Are provided on a concentric circle with the second transmission shaft 24 as the center. The front and rear end portions of the

planetary gears

30, 30... Are respectively provided with a gear portion 30 b and a gear portion 30 c having teeth formed on the outer periphery thereof (see FIG. 3). The gear portion 30 b of the planetary gear 30 meshes with the gear portion 27 b of the internal gear 27 and the gear portion 25 a of the sun gear 25. The gear portion 30 c of the planetary gear 30 meshes with the gear portion 28 a of the third transmission gear 28.

The mode switching clutch 31 is provided inside the carrier 29, and is in a state where either the third transmission gear 28 or the carrier 29 and the second transmission shaft 24 are connected so as not to be relatively rotatable, and the third transmission gear. 28, the carrier 29, and the second transmission shaft 24 are switched to a state in which the connection is released so as to be relatively rotatable.
The mode switching clutch 31 mainly includes a low speed side clutch 31a and a high speed side clutch 31b.

The low speed side clutch 31a enables connection / disconnection of power between the carrier 29 that is the low speed side output of the planetary gear mechanism 20 and the second transmission shaft 24 that is the output shaft of the HMT4. The low speed side clutch 31 a is provided at the rear portion of the mode switching clutch 31.

The high speed side clutch 31b enables connection / disconnection of power between the third transmission gear 28 that is the high speed side output of the planetary gear mechanism 20 and the second transmission shaft 24 that is the output shaft of the HMT 4. The high speed side clutch 31 b is provided at the front portion of the mode switching clutch 31.

The third transmission shaft 32 is a shaft-like member arranged on the same axis as the output shaft 12a of the hydraulic motor 12. The third transmission shaft 32 is provided behind the output shaft 12a so as not to rotate relative to the output shaft 12a. The third transmission shaft 32 is rotatably supported by the planetary case 21.

The fourth transmission gear 33 is provided at the rear end of the third transmission shaft 32 so as not to rotate relative to the third transmission shaft 32. The fourth transmission gear 33 meshes with the gear portion 27 a of the internal gear 27.

The fifth transmission gear 34 is provided at the rear end portion of the first transmission shaft 22 so as to be rotatable relative to the first transmission shaft 22. The front end portion and the rear end portion of the fifth transmission gear 34 are respectively provided with a gear portion 34a and a gear portion 34b having teeth formed on the outer periphery thereof (see FIG. 3). The gear portion 34 a of the fifth transmission gear 34 meshes with the gear portion 29 a of the carrier 29.

The reverse gear 35 is provided on the second transmission shaft 24 and behind the carrier 29 so as to be rotatable relative to the second transmission shaft 24. The rear end portion of the reverse gear 35 is provided with a gear portion 35a having teeth formed on the outer periphery thereof.

The sixth transmission gear 36 is disposed so as to mesh with the gear portion 34b of the fifth transmission gear 34 and the gear portion 35a of the reverse gear 35 (see FIG. 2). The sixth transmission gear 36 is supported so as to be rotatable about a support shaft 36a. For convenience, the sixth transmission gear 36 and the support shaft 36a in FIG. 3 are not shown.

The forward / reverse switching clutch 37 is provided in front of the reverse gear 35 and is disconnected so that the reverse gear 35 and the second transmission shaft 24 are connected so as not to rotate relative to each other. The state is switched.

The operation mode of the planetary gear mechanism 20 configured as described above will be described.
The power generated by the engine 3 is transmitted to the first transmission gear 23 via the drive shaft 13. The power transmitted to the first transmission gear 23 is transmitted to the

planetary gears

30, 30... Via the second transmission gear 26 and the sun gear 25.
On the other hand, the power generated by the engine 3 and shifted in the HST 10 is transmitted to the third transmission shaft 32 via the output shaft 12 a of the hydraulic motor 12. The power transmitted to the third transmission shaft 32 is transmitted to the

planetary gears

30, 30... Via the fourth transmission gear 33 and the internal gear 27.

The

planetary gears

30, 30... Rotate around the

planetary shafts

30 a, 30 a, and the second transmission shaft 24 by the power from the two paths transmitted to the

planetary gears

30, 30. Revolves as a center. Power is transmitted to the third transmission gear 28 by the rotation of the planetary gears 30. Power is transmitted to the carrier 29 by the revolution of the planetary gears 30.
When the carrier 29 and the second transmission shaft 24 are connected by the low speed side clutch 31 a, the power of the carrier 29 is transmitted to the second transmission shaft 24. When the third transmission gear 28 and the second transmission shaft 24 are connected by the high-speed clutch 31b, the power of the third transmission gear 28 is transmitted to the second transmission shaft 24.

Further, the power of the carrier 29 is transmitted to the reverse gear 35 through the fifth transmission gear 34 and the sixth transmission gear 36. In a state where the mode switching clutch 31 releases the connection between the third transmission gear 28 and the carrier 29 and the second transmission shaft 24, the reverse rotation gear 35 and the second transmission shaft 24 are connected by the forward / reverse switching clutch 37. In this case, the power of the reverse gear 35 is transmitted to the second transmission shaft 24. In this case, the second transmission shaft 24 rotates in the direction opposite to the rotation direction when the mode switching clutch 31 connects the third transmission gear 28 or the carrier 29 and the second transmission shaft 24.

As described above, the power generated by the engine 3 and the power generated by the engine 3 and shifted in the HST 10 are combined in the planetary gear mechanism 20 and the combined power (hereinafter simply referred to as “combined power”). Is output from the second transmission shaft 24.

As shown in FIG. 2, the subtransmission mechanism 40 shifts and outputs the combined power transmitted from the planetary gear mechanism 20. In the present embodiment, by switching the auxiliary transmission clutch 41, the transmission gear ratio can be switched to a low speed or a high speed, or to a neutral state in which the transmission of power is cut off.
The power shifted in the auxiliary transmission mechanism 40 is transmitted to the differential mechanism 50 via the auxiliary transmission output shaft 42.

The differential mechanism 50 distributes and outputs the power transmitted from the subtransmission mechanism 40 to the left and right. The distributed power is transmitted to the left and right

rear wheels

6 and 6, respectively.

In addition, description is abbreviate | omitted about the structure for the power transmission from the engine 3 to the front wheels 5 * 5 in the work vehicle 1 which concerns on this embodiment.

The control mechanism 60 is for controlling the HMT 4. The control mechanism 60 mainly includes a swash plate control actuator 101, a low speed solenoid valve 102, a high speed solenoid valve 103, a reverse rotation solenoid valve 104, a rotation speed detecting means 105, a speed change lever 7c, a control device 100, and the like.

The swash plate control actuator 101 changes the gear ratio of the HST 10 by changing the inclination angle of the movable swash plate 11a of the hydraulic pump 11. The swash plate control actuator 101 of this embodiment is configured using hydraulic equipment (for example, a hydraulic cylinder or the like).

The low speed solenoid valve 102 supplies hydraulic oil to the low speed side clutch 31a, and operates the low speed side clutch 31a so that the carrier 29 and the second transmission shaft 24 cannot be rotated relative to each other.

The high-speed solenoid valve 103 supplies hydraulic oil to the high-speed side clutch 31b and operates the high-speed side clutch 31b so that the third transmission gear 28 and the second transmission shaft 24 cannot be rotated relative to each other. .

The reverse solenoid valve 104 supplies hydraulic oil to the forward / reverse switching clutch 37, and operates the forward / reverse switching clutch 37 so that the reverse gear 35 and the second transmission shaft 24 cannot be rotated relative to each other. .

The rotation speed detection means 105 detects the rotation speed of the auxiliary transmission output shaft 42. The rotation speed detection means 105 is an embodiment of the transmission ratio detection means according to the present invention.

The transmission lever 7c sets the traveling speed of the work vehicle 1 by changing the transmission ratio of the HMT 4 as described above.

The control device 100 controls the operations of the swash plate control actuator 101, the low speed solenoid valve 102, the high speed solenoid valve 103, and the reverse rotation solenoid valve 104.

The control device 100 is connected to the swash plate control actuator 101, can control the operation of the swash plate control actuator 101, and in turn can control the tilt angle of the movable swash plate 11a of the hydraulic pump 11. .
Since the swash plate control actuator 101 is actuated by hydraulic pressure, the control signal from the control device 100 is transmitted to the swash plate control actuator 101 until the movable swash plate 11a is actually actuated by the swash plate control actuator 101. There is a delay of a certain time. Hereinafter, the delay time is defined as “operation dead time T _H ”.

The control device 100 is connected to the low-speed solenoid valve 102, can control the operation of the low-speed solenoid valve 102, and thus can control the operation of the low-speed side clutch 31a.

The control device 100 is connected to the high-speed solenoid valve 103, can control the operation of the high-speed solenoid valve 103, and thus can control the operation of the high-speed side clutch 31b.
The low speed side clutch 31a and the high speed side clutch 31b are operated by hydraulic pressure. For this reason, after the control signal S from the control device 100 is transmitted to the low speed solenoid valve 102 and the high speed solenoid valve 103, the pressure P applied to the low speed side clutch 31a and the high speed side clutch 31b reaches the set pressure Ps, and actually There is a delay of a certain time before the operation. In the following, a delay time from when the control signal S for operating the low speed side clutch 31a and the high speed side clutch 31b is transmitted to when the set pressure Ps is actually applied to the low speed side clutch 31a and the high speed side clutch 31b and is operated the as "clutch boosting time T _u", the control signal S for stopping the operation of the low speed side clutch 31a and the high speed clutch 31b is transmitted, actually according to the low speed side clutch 31a and the high speed side clutch 31b set pressure The delay time until Ps decreases and the operation is released is defined as “clutch pressure reduction time T _d ”.

The control device 100 is connected to the reverse solenoid valve 104 and can control the operation of the reverse solenoid valve 104.

The control device 100 is connected to the speed change lever 7c (more specifically, an operation amount detection means 7d for detecting the operation amount of the speed change lever 7c), and receives a detection signal of the operation amount of the speed change lever 7c. It is possible to detect the setting value of the transmission ratio of the HMT 4 according to 7c (hereinafter simply referred to as “transmission ratio command value R _o ”). In the present embodiment, the speed of the work vehicle 1 is set by the speed change lever 7c. However, the present invention is not limited to this, and the speed can be set by a speed change pedal or the like.

The control device 100 is connected to the rotation speed detection means 105 and can receive a detection signal of the rotation speed of the auxiliary transmission output shaft 42 by the rotation speed detection means 105. As a result, the speed ratio of the HMT 4 and the work vehicle 1 It is possible to calculate the gear ratio and speed.

In the present embodiment, the gear ratio of the HMT 4 and the speed of the work vehicle 1 are detected from the rotation speed of the auxiliary transmission output shaft 42. However, the present invention is not limited to this, and the

front wheels

5 and 5 It is also possible to adopt a configuration in which the speed of the work vehicle 1 is detected from the number of rotations of the

rear wheels

6 and 6 and the number of rotations of other shafts and gears.

Specifically, the control device 100 may be configured such that a CPU, a ROM, a RAM, an HDD, and the like are connected by a bus, or may be configured by a one-chip LSI or the like.
The control device 100 stores various programs and data for controlling the operation of the swash plate control actuator 101 and the like. The control device 100 controls the operations of the swash plate control actuator 101, the low speed solenoid valve 102, the high speed solenoid valve 103, and the like based on the operation amount of the speed change lever 7c.

Below, the map 110 which the control apparatus 100 comprises is demonstrated using FIG.
The map 110 shows a calculation formula for calculating the inclination angle α of the movable swash plate 11 a of the hydraulic pump 11 corresponding to the gear ratio R of the work vehicle 1.
Here, the gear ratio R in the present embodiment is a ratio between the power shifted in the HMT 4 (specifically, the rotational speed of the auxiliary transmission output shaft 42) and the power of the engine 3 (engine rotational speed). .
Note that the relationship shown in FIG. 4 is a theoretical relationship that assumes a case where the work vehicle 1 is not loaded. Further, it is assumed that the rotational speed of the engine 3 is a constant value, and the auxiliary transmission clutch 41 is set to one of low speed and high speed.

The vertical axis of the map 110 indicates the inclination angle α of the movable swash plate 11 a of the hydraulic pump 11. The movable swash plate 11a can change the inclination angle α from α _max to −α _max .
Here, the hydraulic motor 12 is rotated in the forward direction (forward rotation) when the inclination angle α is in the range of 0 <α ≦ α _max . Hereinafter, this range is defined as “forward rotation side”. Further, the hydraulic motor 12 rotates (reverses) in the direction opposite to the forward direction in the range where the inclination angle α is in the range of −α _max ≦ α <0. Hereinafter, this range is defined as “reverse rotation side”.
Α _max is an angle at which the movable swash plate 11a of the hydraulic pump 11 can be tilted to the maximum in the forward rotation direction.
The horizontal axis of the map 110 indicates the gear ratio R of the work vehicle 1. In the map 110, with R = 0 as a boundary, the right side of the drawing (FIG. 4) shows the speed ratio during forward travel, and the left side of the drawing (FIG. 4) shows the speed ratio during reverse travel.

The straight line L shows the relationship between the inclination angle α and the gear ratio R when only the low-speed clutch 31a is operated. That is, the straight line L indicates a calculation formula for calculating the inclination angle α based on the transmission gear ratio R when only the low speed side clutch 31a is operated.
In this case, as the inclination angle α is changed from the reverse rotation side to the normal rotation side, the gear ratio increases from the forward side. Hereinafter, this state is simply referred to as “low speed mode ML”.
Also, in the case of alpha =-.alpha. _A, synthesized synthesized power in HMT4 is 0 and R = 0. That is, the work vehicle 1 stops.

A straight line H shows the relationship between the inclination angle α and the gear ratio R when only the high-speed clutch 31b is operated. That is, the straight line H indicates a calculation formula for calculating the inclination angle α based on the speed ratio R when only the high-speed clutch 31b is operated.
In this case, as the inclination angle α is changed from the forward rotation side to the reverse rotation side, the speed ratio R increases from the forward side. Hereinafter, this state is simply referred to as “high-speed mode MH”.

The straight line B shows the relationship between the inclination angle α and the gear ratio R when only the forward / reverse switching clutch 37 is operated. That is, the straight line B shows a calculation formula for calculating the inclination angle α based on the gear ratio R when only the forward / reverse switching clutch 37 is operated.
In this case, as the inclination angle α is changed from the reverse rotation side to the normal rotation side, the transmission gear ratio R increases to the reverse side. This state is simply referred to as “reverse mode MB”.

The straight line L and the straight line H are configured to intersect at a point where α = α _max . The gear ratio R and the inclination angle α at this point are defined as “switching gear ratio R _c ” and “switching inclination angle α _c ”. That is, α _c = α _max .

In the present embodiment, the inclination of the straight line L and the inclination of the straight line H are set so that the absolute values thereof are equal and the signs are different from each other. By setting in this way, loads applied to the HST 10 in the low speed mode ML and the high speed mode MH are equalized. As a result, even if the low speed mode ML and the high speed mode MH are switched, the transmission gear ratio R of the work vehicle 1 is theoretically the same, and the change in the transmission gear ratio R due to the shift (switching between the low speed mode ML and the high speed mode MH). Shock) can be minimized.
However, even if the absolute values do not match (not equal to each other), the change in the speed ratio R at the time of switching between the low speed mode ML and the high speed mode MH is practically small. For this reason, this invention is not limited to the structure with which the said absolute value corresponds, The structure from which the said absolute value differs may be sufficient.
The straight line L and the straight line B, the point to be α = -α _A, i.e. intersect at a point to be R = 0.

Hereinafter, the control mode of the HMT 4 by the control device 100 will be described.

First, the relationship between parameters will be described with reference to FIGS.
Controller 100, the speed ratio command value R _o is set by the shift lever 7c, it calculates a limit speed ratio command value R _ol based on the gear ratio command value R _o. The limit speed ratio command value R _ol, to actual gear ratio R _t is prevented from varying to abruptly speed ratio command value R _o, the time rate of change of the gear ratio command value R _o at a predetermined inclination Restricted.

The control device 100 determines the inclination based on the limiting speed ratio command value R _ol and each calculation formula shown in the map 110 (the straight line L in FIG. 4 in the low speed mode ML and the straight line H in FIG. 4 in the high speed mode MH). An angle command value α _o is calculated. The inclination angle command value α _o is a value of the inclination angle α corresponding to the limiting speed ratio command value R _ol .

The control device 100 calculates the actual speed ratio R _t based on the rotation speed of the auxiliary transmission output shaft 42 detected by the rotation speed detection means 105 and the rotation speed of the engine 3. The actual speed ratio _Rt is the value of the actual speed ratio R of the work vehicle 1.

The control device 100 calculates the actual inclination angle α _t based on the actual speed ratio R _t and each calculation formula (the straight line L in FIG. 4 in the low speed mode ML and the straight line H in FIG. 4 in the high speed mode MH). The actual inclination angle α _t is a value of the inclination angle α corresponding to the actual speed ratio R _t .

The control device 100 calculates the post-FB tilt angle command value α _of by comparing the tilt angle command value α _o and the actual tilt angle α _t and feeding back. The post-FB tilt angle command value α _of is a value obtained by adding the feedback amount F to the tilt angle command value α _o . Note that PI control or the like can be used as a feedback technique in the present embodiment, but the present invention does not limit the technique.

Hereinafter, with reference to FIG. 5, the control of the HMT 4 performed by the control device 100 using the above parameters in the low speed mode ML and the high speed mode MH will be described. The horizontal axis in FIG. 5 indicates the elapsed time ET.

The control device 100 controls the operation of the swash plate control actuator 101 so that the actual speed ratio _Rt becomes the speed ratio command value _Ro .
More specifically, the control device 100 transmits a control signal to the swash plate control actuator 101 so that the actual inclination angle α _t of the movable swash plate 11a becomes the post-FB inclination angle command value α _of . The swash plate control actuator 101 changes the actual inclination angle α _t of the movable swash plate 11a according to the control signal.
In this way, by controlling the actual inclination angle α _t of the movable swash plate 11a to become the post-FB inclination angle command value α _of , the actual transmission ratio R _t becomes the limited transmission ratio command value R _ol. Can be controlled.
Further, the control unit 100, by approaching the limit speed ratio command value R _ol to gradually speed ratio command value R _o, can be actual gear ratio R _t is controlled to be gear ratio command value R _o .

The control in the low speed mode ML and the high speed mode MH as described above is defined as “normal control” and will be described below.

Next, referring to FIGS. 6 to 12, the control device 100 performs the switching control from the low speed mode ML to the high speed mode MH (hereinafter, referred to as “speed ratio control value R _o”) when the speed ratio command value Ro is larger than the switching speed ratio R _c . The description will simply be made as “first control mode”.
The low speed mode ML is switched to the high speed mode MH by the control device 100 via the switching control mode.
The switching control mode is divided into an acceleration first transition mode MA1, an acceleration second transition mode MA2, and an acceleration third transition mode MA3 (step S120 to step S140 in FIG. 7).

As shown in FIG. 7, in step S110, the control device 100 controls the HMT 4 in the low speed mode ML (see the low speed mode ML in FIG. 6). Below, the detail is demonstrated.

As shown in FIG. 8, in step S111, the control unit 100, the actual gear ratio _{R t} is equal to or less than 95% of the speed change ratio command value _{R o.}
When the actual speed ratio R _t is not less than 95% of the speed ratio command value _Ro , that is, when the actual speed ratio R _t is greater than or equal to 95% of the speed ratio command value _Ro , the control device 100 again performs step S111. Process.
When the actual gear ratio _Rt is less than 95% of the gear ratio command value _Ro , the control device 100 proceeds to step S112.

As described above, the control unit 100 determines in step S111, the actual gear ratio _{R t} is whether the host vehicle has reached the speed ratio command value _{R o.} That is, when the actual gear ratio R _t is not less than 95% of the speed change ratio command value R _o is deemed to actual gear ratio R _t reaches the speed change ratio command value R _o. This is to take account of errors and power transmission loss.

In step S112, control device 100 determines whether or not post-FB inclination angle command value α _of is greater than or equal to switching inclination angle α _c .
When the post-FB inclination angle command value α _of is not greater than or equal to the switching inclination angle α _c , that is, when the post-FB inclination angle command value α _of is less than the switching inclination angle α _c , the control device 100 performs the process of step S111 again. Do.
When the post-FB tilt angle command value α _of is greater than or equal to the switching tilt angle α _c , the control device 100 proceeds to step S120.

As described above, when it is determined in step S112 that the post-FB inclination angle command value α _of has reached the switching inclination angle α _c , the control apparatus 100 shifts to the switching control mode (step S120 and subsequent steps). Thus, the switching timing to shift to control mode can be determined without being affected by the inclination or the like of the time variation of the actual gear ratio R _t.

As shown in FIG. 7, in step S120, the control device 100 controls the HMT 4 in the acceleration first transition mode MA1 (see the acceleration first transition mode MA1 in FIG. 6). Below, the detail is demonstrated.

As shown in FIG. 9, in step S121, the control unit 100 stops the time variation of the limit speed ratio command value _{R ol,} i.e., to fix the limits gear ratio command value _{R ol} to a constant value (of t1 in FIG. 6 Time). At this time, control device 100 also fixes post-FB inclination angle command value α _{of at a} constant value. The value _of the post-FB tilt angle command value α _{of in} this case is a value obtained by adding the tilt correction amount Δα to the tilt angle command value α _o . Further, the feedback amount F immediately before the transition to the acceleration first transition mode MA1 is used as the inclination correction amount Δα.
The control apparatus 100 transfers to step S122 after performing the said process.

In step S122, the control device 100 starts counting time T (at time t1 in FIG. 6).
After performing the above process, the control device 100 proceeds to step S123.

In step S123, the control device 100 transmits a control signal S for operating the high speed side clutch 31b to the high speed solenoid valve 103 (at time t1 in FIG. 6).
After performing the above processing, the control device 100 proceeds to step S124.

In step S124, the control unit 100 determines whether a time T operation dead time _{T H} above.
If not time T operation dead time _{T H} above, i.e., if the time T is less than the dead time operation _{T H,} the control device 100 performs the process of step S124 again.
If the time T is the operation dead time _{T H} above, the control unit 100 proceeds to step S125.

In step S125, the controller 100, the actual gear ratio _{R t} is equal to or less than 95% of the speed change ratio command value _{R o.}
When the actual gear ratio R _t is not less than 95% of the gear ratio command value _Ro , that is, when the actual gear ratio R _t is 95% or more of the gear ratio command value _Ro , the control device 100 proceeds to step S111. (See FIGS. 8 and 9).
When the actual gear ratio _Rt is less than 95% of the gear ratio command value _Ro , the control device 100 proceeds to step S130.

As described above, the control device 100 whether or not the processing of step S124 and step S125, the actual gear ratio _{R t} without switching from the low speed mode ML fast mode MH can reach more than 95% of the speed change ratio command value _{R o} Can be determined.
That is, the control device 100, when the inclination angle command value alpha _of after FB operated dead time T _H has elapsed after reaching the switching angle of inclination alpha _c, the actual gear ratio R _t is a gear ratio command value R _o 95 If it is% or more, it is determined that there is no need to switch from the low speed mode ML to the high speed mode MH. In this case, since switching between the low-speed side clutch 31a and the high-speed side clutch 31b is not performed, unnecessary clutch switching is not performed, and deterioration of ride comfort of the operator due to mode switching can be prevented.

As shown in FIG. 7, in step S130, the control device 100 controls the HMT 4 in the acceleration second transition mode MA2 (see the acceleration second transition mode MA2 in FIG. 6). Below, the detail is demonstrated.

As shown in FIG. 10, in step S131, the control device 100 changes the calculation formula for calculating the tilt angle command value α _o and the actual tilt angle α _t from the straight line L to the straight line H (t2 in FIG. 6). Of time).
After performing the above processing, the control device 100 proceeds to step S132.

In step S132, the control unit 100 changes the limit speed ratio command value _{R ol} to switch speed ratio _{R c} (time point t2 in FIG. 6).

By the processing in step S131 and step S132, the tilt angle command value α _o , the post-FB tilt angle command value α _of , and the actual tilt angle α _t change as shown in FIG.
That is, the inclination angle command value α _o changes on the straight line H to a value (switching inclination angle α _c ) corresponding to the limited transmission gear ratio command value R _ol (switching transmission gear ratio R _c ).
The post-FB tilt angle command value α _of changes on the straight line H to a value obtained by subtracting the tilt correction amount Δα from the tilt angle command value α _o . As shown in FIG. 11, the sign of the inclination of the inclination angle α with respect to the gear ratio R is reversed in the low speed mode ML and the high speed mode MH. Therefore, in the high speed mode MH, the inclination is opposite to the low speed mode ML. This is because it is necessary to subtract the inclination correction amount Δα from the angle command value α _o . Thus, by using the post-FB inclination angle command value α _of corrected by the inclination correction amount Δα, the transition of the speed ratio R after switching to the high speed mode MH becomes smooth.
The actual inclination angle α _t changes to a value on the straight line H while the speed ratio R remains unchanged.

The control apparatus 100 transfers to step S140 after performing the said process.

As shown in FIG. 7, in step S140, the control device 100 controls the HMT 4 in the acceleration third transition mode MA3 (see the acceleration third transition mode MA3 in FIG. 6). Below, the detail is demonstrated.

As shown in FIG. 12, in step S141, the control device 100 stops the transmission of the control signal S for operating the low speed side clutch 31a (at time t3 in FIG. 6).
After performing the said process, the control apparatus 100 transfers to step S142.

In step S142, the control device 100 restarts the time change of the limited speed ratio command value _Rol (at time t3 in FIG. 6).
After performing the above processing, the control device 100 proceeds to step S150.

As shown in FIG. 7, in step S150, the control device 100 performs normal control in the high-speed mode MH.

Further, as shown in FIG. 6, the set time T1 (from t1 to t2) during which the control based on the acceleration first transition mode MA1 is performed is “clutch boosting time T _u − (operation dead time T _H −simultaneous. Insertion time T _w ) ”.
A set time T2 (from t2 to t3) that is a time during which the control based on the acceleration second transition mode MA2 is performed is set to be “operation dead time T _H −clutch pressure reduction time T _d ”.
A set time T3 (from t3 to t4) during which the control based on the acceleration third transition mode MA3 is performed is set to be “clutch pressure reduction time T _d −simultaneous insertion time T _w ”.
Note that the simultaneous fitting time T _w, is the time and the low-speed side clutch 31a and the high speed clutch 31b is activated simultaneously.

As described above, if the control apparatus 100 was switched control from the low speed mode ML to the high speed mode MH, the high-speed mode MH, and the low-speed side clutch 31a and the high speed side clutch 31b is, at the same time only during the simultaneous fitting time T _w It operates (hereinafter simply referred to as “simultaneous insertion”). As a result, it is possible to prevent the power transmission from being interrupted in the HMT 4 when the clutch is switched, and it is possible to smoothly switch the clutch even when a heavy load is applied to the work vehicle 1. is there.
Further, in step S132 (FIG. 10), by changing the advance limit speed ratio command value R _ol the switch speed ratio R _c, when the actual gear ratio R _t is increased to switch speed ratio R _c in the subsequent simultaneous fitting The shift can be smoothly performed in step (b).

As described above, the HMT 4 of this embodiment is
An HST 10 in which at least one of the hydraulic pump 11 and the hydraulic motor 12 is a variable displacement type using a movable swash plate 11a;
A planetary gear mechanism 20 that combines and shifts the power from the engine 3 and the power from the hydraulic motor 12;
A swash plate control actuator 101 that adjusts the inclination angle α of the movable swash plate 11a by hydraulic pressure;
A low-speed side clutch 31a that enables connection and disconnection of power between the carrier 29 of the planetary gear mechanism 20 and the second transmission shaft 24;
A high-speed side clutch 31b that enables connection and disconnection of power between the third transmission gear 28 and the second transmission shaft 24 of the planetary gear mechanism 20;
A low-speed solenoid valve 102 for operating the low-speed clutch 31a by hydraulic pressure;
A high-speed solenoid valve 103 for operating the high-speed clutch 31b by hydraulic pressure;
A transmission lever 7c for setting a transmission ratio command value _Ro that is a target value of the transmission ratio R;
A rotation speed detecting means 105 for detecting the actual gear ratio _{R t,}
Actual gear ratio _{R t} is the speed ratio command value swash plate control actuator 101 such that _{R o,} a control unit 100 for controlling the operation of the low-speed solenoid valve 102 and the high-speed solenoid valve 103,
In HMT4 comprising:
The control device 100
In the low speed mode ML and the high speed mode MH, comprising a map 110 showing a calculation formula for calculating the inclination angle α corresponding to the gear ratio R,
Calculates a limit speed ratio command value R _ol which varies as a gear ratio command value R _o at a predetermined time rate of change,
Based on the map 110, a post-FB inclination angle command value α _of that changes at a predetermined time change rate corresponding to the limited speed ratio command value R _ol is calculated,
The operation of the swash plate control actuator 101 is controlled so that the actual inclination angle α _t of the movable swash plate 11a becomes the post-FB inclination angle command value α _of ,
If FB after tilting angle command value alpha _of reaches a predetermined switching inclination angle alpha _c, it is to shift to switching control mode for switching the connection and disconnection of the low speed side clutch 31a and the high speed clutch 31b.
With this configuration, without the timing of transition to switching control mode is affected by the slope of the time variation of the actual gear ratio R _t, it is possible to reliably transition to switching control mode. Further, as in the present embodiment, by setting the value of the switching inclination angle α _c to α _max , the ability of the HST 10 can be utilized to the maximum, so that the HST 10 can be miniaturized and consequently the HMT 4 can be miniaturized. It becomes possible.

Moreover, the control apparatus 100 of this embodiment is
In the switching control mode, it is necessary from the time when the post-FB inclination angle command value α _of reaches the switching inclination angle α _c until the movable swash plate 11a actually operates after the swash plate control actuator 101 receives the control signal. by do operation dead time T _H has elapsed, the actual gear ratio R _t only if it does not reach the speed ratio command value R _o, in which switching the connection and disconnection of the low speed side clutch 31a and the high speed clutch 31b.
With this configuration, the low-speed mode ML and the high-speed mode MH are not switched until unnecessary, so the number of times of switching is reduced as much as possible, and the occurrence of shift shocks associated with the switching is reduced. Can be made. Moreover, in the work vehicle 1 including the HMT 4 according to the present embodiment, it is possible to prevent the operator's riding comfort from being deteriorated due to the shift shock.

Moreover, the control apparatus 100 of this embodiment is
When switching the connection / disconnection of the low speed side clutch 31a and the high speed side clutch 31b in the switching control mode, the low speed side clutch 31a and the high speed side clutch 31b are operated simultaneously during the simultaneous insertion time _Tw (predetermined time).
With this configuration, it is possible to prevent power transmission from being interrupted in the HMT 4 when switching between the low speed mode ML and the high speed mode MH. As a result, even when a large load is applied to the HMT 4, it is possible to smoothly switch between the low speed mode ML and the high speed mode MH.

Moreover, the control apparatus 100 of this embodiment is
In switching control mode to switch from the low speed mode ML fast mode MH, if limited speed ratio command value R _ol is smaller than switch speed ratio R _c corresponding to speed ratio command value R _o and switching the inclination angle alpha _c,
The limit speed ratio command value R _ol, followed (in the first control mode, the switch speed ratio R _c) smaller value among the speed change ratio command value R _o or switch speed ratio R _c was increased to, low-speed clutch The connection / disconnection of 31a and the high speed side clutch 31b is switched.
With this configuration, when the low-speed side clutch 31a and the high speed clutch 31b is simultaneously fitted to the actual gear ratio R _t is increased to switch speed ratio R _c may, enabling smooth transmission (accelerating) Become.

Next, with reference to up to 15 7 and 13, when the speed change ratio command value R _o is switch speed ratio R _c is less than, aspects from the low-speed mode ML by the control device 100 of the switching control of the high-speed mode MH (Hereinafter simply referred to as “second control mode”) will be described.

As shown in FIG. 7, in step S110, the control device 100 controls the HMT 4 in the low speed mode ML (see the low speed mode ML in FIG. 13). The process in step S110 of the second control mode is substantially the same as the process in step S110 of the first control mode.

As shown in FIG. 7, in step S120, the control device 100 controls the HMT 4 in the acceleration first transition mode MA1 (see the acceleration first transition mode MA1 in FIG. 13). The process in step S120 of the second control mode is substantially the same as the process in step S120 of the first control mode.

As shown in FIG. 7, in step S130, the control device 100 controls the HMT 4 in the acceleration second transition mode MA2 (see the acceleration second transition mode MA2 in FIG. 13). Below, the detail is demonstrated.

As shown in FIG. 14, in step S231, the control device 100 changes the calculation formula for calculating the tilt angle command value α _o and the actual tilt angle α _t from the straight line L to the straight line H (t2 in FIG. 13). Of time).
After performing the above processing, the control device 100 proceeds to step S232.

In step S232, the control unit 100 changes the limit speed ratio command value _{R ol} the speed ratio command value _{R o} (time point t2 in FIG. 13).

By the processing in steps S231 and S232, the tilt angle command value α _o , the post-FB tilt angle command value α _of , and the actual tilt angle α _t change as shown in FIG.
That is, the inclination angle command value α _o changes on the straight line H to a value corresponding to the limited transmission gear ratio command value R _ol (transmission gear ratio command value R _o ).
The post-FB tilt angle command value α _of changes on the straight line H to a value obtained by subtracting the tilt correction amount Δα from the tilt angle command value α _o .
The actual inclination angle α _t changes to a value on the straight line H while the speed ratio R remains unchanged.

As shown in FIG. 7, in step S140, the control device 100 controls the HMT 4 in the acceleration third transition mode MA3 (see the acceleration third transition mode MA3 in FIG. 13). The process in step S140 of the second control mode is substantially the same as the process in step S140 of the first control mode.

As described above, the control device 100 of the present embodiment is
In switching control mode to switch from the low speed mode ML fast mode MH, if limited speed ratio command value R _ol is smaller than switch speed ratio R _c corresponding to speed ratio command value R _o and switching the inclination angle alpha _c,
The limit speed ratio command value R _ol, (in the first control mode, the speed change ratio command value R _o) smaller value among the speed change ratio command value R _o or switch speed ratio R _c after increasing up, low-speed The connection / disconnection of the clutch 31a and the high speed side clutch 31b is switched.
With this configuration, when the low-speed side clutch 31a and the high speed clutch 31b is simultaneously fitted to the actual gear ratio R _t is increased to switch speed ratio R _c may, enabling smooth transmission (accelerating) Become.

Next, referring to FIG. 7 and FIGS. 16 to 18, a mode of switching control from the low speed mode ML to the high speed mode MH by the control device 100 when the actual speed ratio Rt is larger than the limit speed ratio command value Rol ( Hereinafter, the “third control mode” will be described. Here, the case where the actual speed ratio Rt is larger than the limit speed ratio command value Rol is, for example, the case where the work vehicle 1 goes down a hill while pulling a heavy object such as a trailer. In this case, it is assumed that the work vehicle 1 is pushed from behind by the trailer.

As shown in FIG. 7, in step S110, the control device 100 controls the HMT 4 in the low speed mode ML (see the low speed mode ML in FIG. 16). The process in step S110 of the third control mode is substantially the same as the process in step S110 of the first control mode.

As shown in FIG. 7, in step S120, the control device 100 controls the HMT 4 in the acceleration first transition mode MA1 (see the acceleration first transition mode MA1 in FIG. 16). The process in step S120 of the third control mode is substantially the same as the process in step S120 of the first control mode.

As shown in FIG. 7, in step S130, the control device 100 controls the HMT 4 in the acceleration second transition mode MA2 (see the acceleration second transition mode MA2 in FIG. 16). Below, the detail is demonstrated.

As shown in FIG. 17, in step S331, the control device 100 changes the calculation formula for calculating the tilt angle command value α _o and the actual tilt angle α _t from the straight line L to the straight line H (t2 in FIG. 16). Of time).

By the processing in step S331, the tilt angle command value α _o , the post-FB tilt angle command value α _of , and the actual tilt angle α _t change as shown in FIG.
That is, the inclination angle command value α _o changes on the straight line H to a value corresponding to the limited speed ratio command value R _ol .
The post-FB tilt angle command value α _of changes on the straight line H to a value obtained by subtracting the tilt correction amount Δα from the tilt angle command value α _o . However, since the value is the same before and after the process of step S331, the value of the post-FB inclination angle command value α _of does not substantially change.
The actual inclination angle α _t changes to a value on the straight line H while the speed ratio R remains unchanged.

As shown in FIG. 7, in step S140, the control device 100 controls the HMT 4 in the acceleration third transition mode MA3 (see the acceleration third transition mode MA3 in FIG. 16). The process in step S140 of the third control mode is substantially the same as the process in step S140 of the first control mode.

Next, with reference to FIGS. 19 to 25, when the speed change ratio command value R _o is switch speed ratio R _c is less than, aspects from the high-speed mode MH by the control device 100 of the switching control to the low-speed mode ML (hereinafter, The description will be simply made as “fourth control mode”.
The high speed mode MH is switched to the low speed mode ML by the control device 100 via the switching control mode.
The switching control mode is divided into a deceleration first transition mode MD1, a deceleration second transition mode MD2, and a deceleration third transition mode MD3 (step S420 to step S440 in FIG. 19).

As shown in FIG. 19, in step S410, the control device 100 controls the HMT 4 in the high speed mode MH (see the high speed mode MH in FIG. 20). Below, the detail is demonstrated.

As shown in FIG. 21, in step S411, the control unit 100, the actual gear ratio _{R t} is equal to or greater than 105% of the speed change ratio command value _{R o.}
If the actual gear ratio _{R t} is not greater than 105% of the speed change ratio command value _{R o,} that is, when the actual gear ratio _{R t} is less than 105% of the speed change ratio command value _{R o,} the control device 100, Step S411 again Perform the process.
If the actual gear ratio _{R t} is larger than 105% of the speed change ratio command value _{R o,} the controller 100 proceeds to step S412.

As described above, the control unit 100 determines in step S411, the actual gear ratio _{R t} is whether the host vehicle has reached the speed ratio command value _{R o.} That is, when the actual gear ratio R _t is less than 105% of the speed change ratio command value R _o is deemed to actual gear ratio R _t reaches the speed change ratio command value R _o. This is to take account of errors and power transmission loss.

In step S412, control device 100 determines whether or not post-FB inclination angle command value α _of is greater than or equal to switching inclination angle α _c .
When the post-FB inclination angle command value α _of is not greater than or equal to the switching inclination angle α _c , that is, when the post-FB inclination angle command value α _of is less than the switching inclination angle α _c , the control device 100 performs the process of step S411 again. Do.
When the post-FB tilt angle command value α _of is greater than or equal to the switching tilt angle α _c , the control device 100 proceeds to step S420.

As described above, when determining that the post-FB inclination angle command value α _of has reached the switching inclination angle α _c in step S412, the control device 100 shifts to the switching control mode (after step S420). Thus, the switching timing to shift to control mode can be determined without being affected by the inclination or the like of the time variation of the actual gear ratio R _t.

As shown in FIG. 19, in step S420, the control device 100 controls the HMT 4 in the deceleration first transition mode MD1 (see the deceleration first transition mode MD1 in FIG. 20). Below, the detail is demonstrated.

As shown in FIG. 22, in step S421, control device 100 stops the change over time of limiting speed ratio command value R _ol , that is, limits limiting speed ratio command value R _ol to a constant value (at t1 in FIG. 20). Time). At this time, control device 100 also fixes post-FB inclination angle command value α _{of at a} constant value. The value _of the post-FB tilt angle command value α _{of in} this case is a value obtained by adding the tilt correction amount Δα to the tilt angle command value α _o . Further, the feedback amount F immediately before the transition to the deceleration first transition mode MD1 is used as the inclination correction amount Δα.
The control apparatus 100 transfers to step S422 after performing the said process.

In step S422, the control device 100 starts counting time T (at time t1 in FIG. 20).
The control apparatus 100 transfers to step S423 after performing the said process.

In step S423, the control device 100 transmits a control signal S for operating the low speed side clutch 31a to the low speed solenoid valve 102 (at time t1 in FIG. 20).
The control apparatus 100 transfers to step S424 after performing the said process.

In step S424, the control unit 100 determines whether a time T operation dead time _{T H} above.
If not time T operation dead time _{T H} above, i.e., if the time T is less than the dead time operation _{T H,} the control device 100 performs the process of step S424 again.
If the time T is the operation dead time _{T H} above, the control unit 100 proceeds to step S425.

In step S425, the control unit 100, the actual gear ratio _{R t} is equal to or greater than 105% of the speed change ratio command value _{R o.}
If the actual gear ratio _{R t} is not greater than 105% of the speed change ratio command value _{R o,} that is, when the actual gear ratio _{R t} is less than 105% of the speed change ratio command value _{R o,} the control unit 100, to step S411 Transition (see FIG. 21 and FIG. 22).
If the actual gear ratio _{R t} is larger than 105% of the speed change ratio command value _{R o,} the controller 100 proceeds to step S430.

As described above, the control device 100 whether or not the processing of step S424 and step S425, the actual gear ratio _{R t} without switching from the high-speed mode MH to the low-speed mode ML can reach below 105% of the speed change ratio command value _{R o} Can be determined.
That is, the control device 100, when the inclination angle command value alpha _of after FB operated dead time _{T H} has elapsed after reaching the switching angle of inclination alpha _c, the actual gear ratio _{R t} is a gear ratio command value _{R o} 105 If it is less than or equal to%, it is determined that there is no need to switch from the high speed mode MH to the low speed mode ML. In this case, since switching between the low-speed side clutch 31a and the high-speed side clutch 31b is not performed, unnecessary clutch switching is not performed, and deterioration of ride comfort of the operator due to mode switching can be prevented.

As shown in FIG. 19, in step S430, the control device 100 controls the HMT 4 in the deceleration second transition mode MD2 (see the deceleration second transition mode MD2 in FIG. 20). Below, the detail is demonstrated.

As shown in FIG. 23, in step S431, the control device 100 changes the calculation formula for calculating the tilt angle command value α _o and the actual tilt angle α _t from the straight line H to the straight line L (t2 in FIG. 20). Of time).
The control apparatus 100 transfers to step S432 after performing the said process.

In step S432, the control unit 100 changes the limit speed ratio command value _{R ol} to switch speed ratio _{R c} (time point t2 in FIG. 20).

By the processing in steps S431 and S432, the tilt angle command value α _o , the post-FB tilt angle command value α _of , and the actual tilt angle α _t change as shown in FIG.
That is, the inclination angle command value α _o changes on the straight line L to a value (switching inclination angle α _c ) corresponding to the limit transmission ratio command value R _ol (switching transmission ratio R _c ).
The post-FB tilt angle command value α _of changes on the straight line L to a value obtained by subtracting the tilt correction amount Δα from the tilt angle command value α _o . As shown in FIG. 24, since the sign of the inclination of the inclination angle α with respect to the gear ratio R is reversed in the low speed mode ML and the high speed mode MH, in the low speed mode ML, the inclination is opposite to the high speed mode MH. This is because it is necessary to subtract the inclination correction amount Δα from the angle command value α _o . Thus, by using the post-FB inclination angle command value α _of corrected by the inclination correction amount Δα, the transition of the speed ratio R after switching to the low speed mode ML becomes smooth.
The actual inclination angle α _t changes to a value on the straight line L without changing the speed ratio R.

The control apparatus 100 transfers to step S440 after performing the said process.

As shown in FIG. 19, in step S440, the control device 100 controls the HMT 4 in the deceleration third transition mode MD3 (see the deceleration third transition mode MD3 in FIG. 20). Below, the detail is demonstrated.

As shown in FIG. 25, in step S441, the control device 100 stops transmitting the control signal S for operating the high speed side clutch 31b (at time t3 in FIG. 20).
After performing the said process, the control apparatus 100 transfers to step S442.

In step S442, the control device 100 restarts the time change of the limited speed ratio command value _Rol (at time t3 in FIG. 20).
After performing the above processing, the control device 100 proceeds to step S450.

As shown in FIG. 19, in step S450, the control device 100 performs normal control in the low speed mode ML.

Further, as shown in FIG. 20, the set time T1 (from t1 to t2) during which the control based on the deceleration first transition mode MD1 is performed is “clutch boosting time T _u − (operation dead time T _H −simultaneous. Insertion time T _w ) ”.
A set time T2 (from t2 to t3) that is a time during which the control based on the acceleration second transition mode MA2 is performed is set to be “operation dead time T _H −clutch pressure reduction time T _d ”.
A set time T3 (from t3 to t4) during which the control based on the acceleration third transition mode MA3 is performed is set to be “clutch pressure reduction time T _d −simultaneous insertion time T _w ”.

As described above, if the control apparatus 100 was switched control from the high-speed mode MH to the low speed mode ML, in the low speed mode ML, and the low-speed side clutch 31a and the high speed side clutch 31b is only during the simultaneous fitting time T _w co Insert. As a result, it is possible to prevent the power transmission from being interrupted in the HMT 4 when the clutch is switched, and it is possible to smoothly switch the clutch even when a heavy load is applied to the work vehicle 1. is there.
Further, in step S432 (FIG. 23), by changing the advance limit speed ratio command value R _ol the switch speed ratio R _c, even when the actual gear ratio Rt is lowered to switch speed ratio Rc in the subsequent simultaneous fitting Shifting can be performed smoothly.

As described above, the control device 100 of the present embodiment is
In switching control mode to switch from the high-speed mode MH to the low-speed mode ML, limited when the gear ratio command value R _ol is greater than switch speed ratio R _c corresponding to speed ratio command value R _o and switching the inclination angle alpha _c,
The limit speed ratio command value R _ol, followed (in the fourth control mode, the switch speed ratio R _c) larger value among the speed change ratio command value R _o or switch speed ratio R _c was reduced to low speed side clutch The connection / disconnection of 31a and the high speed side clutch 31b is switched.
With this configuration, when the low-speed side clutch 31a and the high speed clutch 31b is simultaneously fitted to the actual gear ratio R _t is reduced to switch speed ratio R _c may, enabling smooth shift (deceleration) Become.

In addition, it can also be set as the structure which performs the control mentioned above using what can be equated with it instead of the gear ratio R, for example, the speed of the work vehicle 1, etc.

Industrial availability

The present invention can be used for a technique of a hydraulic-mechanical transmission, and more specifically, can be used for a technique for controlling the operation of the hydraulic-mechanical transmission.

Claims

A hydraulic continuously variable transmission mechanism in which at least one of a hydraulic pump or a hydraulic motor is a variable displacement type using a movable swash plate;
A planetary gear mechanism that combines and shifts the power from the drive source and the power from the hydraulic motor;
A swash plate control actuator for adjusting the inclination angle of the movable swash plate by hydraulic pressure;
A low speed side clutch that enables connection and disconnection of power between the low speed side output of the planetary gear mechanism and the HMT output shaft;
A high-speed clutch that enables connection and disconnection of power between the high-speed output of the planetary gear mechanism and the HMT output shaft;
A low-speed solenoid valve that operates the low-speed side clutch hydraulically;
A high-speed solenoid valve for hydraulically actuating the high-speed side clutch;
Gear ratio setting means for setting a gear ratio command value which is a target value of the gear ratio;
Gear ratio detecting means for detecting an actual gear ratio;
A control device for controlling operations of the swash plate control actuator, the low speed solenoid valve, and the high speed solenoid valve so that the actual speed ratio becomes the speed ratio command value;
In a hydraulic-mechanical transmission comprising:
The controller is
Comprising a map showing a calculation formula for calculating the tilt angle corresponding to the gear ratio;
A limiting speed ratio command value that changes so as to become the speed ratio command value at a predetermined time change rate is calculated;
Based on the map, a post-FB inclination angle command value that changes at a predetermined rate of time change corresponding to the limited speed ratio command value is calculated,
Controlling the operation of the swash plate control actuator so that the actual tilt angle of the movable swash plate becomes the post-FB tilt angle command value;
A hydraulic-mechanical transmission that shifts to a switching control mode for switching between connection and disconnection of the low-speed side clutch and the high-speed side clutch when the post-FB inclination angle command value reaches a predetermined switching inclination angle.
The controller is
In the switching control mode, it is necessary from the time when the post-FB inclination angle command value reaches the switching inclination angle until the movable swash plate actually operates after the control signal is received by the swash plate control actuator. 2. The hydraulic-mechanical type according to claim 1, wherein the connection between the low speed side clutch and the high speed side clutch is switched only when the actual speed ratio does not reach the speed ratio command value before the operation dead time elapses. Transmission device.
The controller is
3. The hydraulic pressure according to claim 1, wherein when the connection between the low speed side clutch and the high speed side clutch is switched in the switching control mode, the low speed side clutch and the high speed side clutch are simultaneously operated for a predetermined time. -Mechanical transmission.
The controller is
In the switching control mode for switching from low speed to high speed, when the limited speed ratio command value is smaller than the switching speed ratio corresponding to the speed ratio command value and the switching inclination angle,
4. The connection between the low speed side clutch and the high speed side clutch is switched after the limit speed ratio command value is increased to a smaller value of the speed ratio command value or the switching speed ratio. 5. Hydraulic-mechanical transmission.
The controller is
In the switching control mode for switching from high speed to low speed, when the limiting speed ratio command value is larger than the switching speed ratio corresponding to the speed ratio command value and the switching inclination angle,
4. The connection / disconnection of the low speed side clutch and the high speed side clutch is switched after the limit speed ratio command value is reduced to a larger value of the speed ratio command value or the switching speed ratio. Hydraulic-mechanical transmission.