JPH05319143A - Control device of torque converter with lock-up of tractor - Google Patents

Abstract

PURPOSE:To improve the labour effectiveness and prevent stalling of engine by constituting a lock-up clutch to be automatically cut when actual engine speed is lowered from a lock-up contact state and a selecting switch comes to be higher than a selected down rate. CONSTITUTION:When a down rate C of engine speed B of an output shaft 12 against actual engine speed A of an engine 5 comes to be lower than a set value, a control unit 1 actuates a lock-up control valve 2, and a lock-up clutch 4 of a torque converter 3 automatically comes to be in a contact state. When the actual engine speed A is lowered and the down rate selected by a selecting switch 7 against engine speed D set by acceleration opening comes to be higher than alpha, beta, gamma, the control unit 1 actuates the lock-up control valve 2 and automatically makes the lock-up clutch 4 in a cut state. Additionally, when a state change-over switch 20 is changed over to manual, it is possible to operate the lock-up clutch 4 to cut and contact it by a change-over switch 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a torque converter with lockup in a tractor or the like.

[0002]

2. Description of the Related Art For example, in a large agricultural tractor, a torque converter (torque converter) with a lockup function is used in a mission in order to improve maneuverability and workability. It is designed to be done automatically. That is, when the down ratio of the output speed of the torque converter to the actual engine speed becomes less than a predetermined value, the lockup clutch of the torque converter is operated by a signal from the control unit. Control is performed to perform lockup disconnection operation.

[0003]

In the above-mentioned prior art, since the lock-up operation is automatically performed, an appropriate operation can be performed in a single mode such as only road traveling, but in the case of an agricultural tractor, road traveling is possible. Not only that, if you have to perform various types of light and heavy work, and if all the work changes from the lock-up contact state to the lock-up disconnection state under the same conditions, it is difficult to hope for optimal control for various work ..

A first object of the present invention is to automatically perform optimum lock-up connection / disconnection control for each of a plurality of light and heavy work modes. A second object of the present invention is to enable lockup connection / disconnection control of a plurality of light and heavy work modes to be manually switched from automatic control. A third object of the present invention is to notify, when the lock-up contact control of the light and heavy work modes is manually performed, when the disconnection control is required.

[0005]

The first specific means for solving the problems in the present invention is that the down rate C of the output shaft speed B of the torque converter 3 with respect to the actual engine speed A is below a predetermined value. At this time, in the control device of the torque converter with lockup in which the lockup clutch 4 of the torque converter 3 is operated via the lockup control valve 2 in response to a signal from the control unit 1, the control unit 1 is an engine set by an accelerator opening degree. The down ratios α, β, γ of the actual engine speed A with respect to the speed D are set to a plurality of stages and a selection switch 7 for selecting one of them is connected, and the down ratios α, β selected by the selection switch 7 are That is, the lock-up clutch 4 is set to be disengageable when γ is reached.

A second concrete means for solving the problems in the present invention is that, in addition to the first concrete means, the control unit 1 has a changeover switch 8 for manually changing over the connecting / disconnecting operation of the lockup clutch 4. That is connected. The third concrete means for solving the problem in the present invention is, in addition to the first concrete means, in the control unit 1, the down rate of the output shaft rotational speed B when the changeover switch 8 is in the lock-up contact operation. That is, the alarm device 9 for notifying that C has become a predetermined value or less is connected.

[0007]

When the engine 5 is started and the crankshaft 11 is rotated, the output shaft 12 is driven via the torque converter 3 and power is transmitted to the transmission 13 at the rear. During the work of the tractor, if the down ratio C of the rotation speed B of the output shaft 12 with respect to the actual rotation speed A of the crankshaft 11 is equal to or less than the set value, the control unit 1 operates the lockup control valve 2 and the torque converter 3 The lockup clutch 4 is automatically brought into the engaged state.

The actual engine speed A decreases from the lockup contact state, and the down ratios α, β, γ selected by the selection switch 7 with respect to the engine speed D set by the accelerator opening (throttle opening). When the above is reached, the control unit 1 operates the lockup control valve 2 to automatically disconnect the lockup clutch 4 of the torque converter 3.

When the control unit 1 is manually controlled by the mode changeover switch 20, the lockup control valve 2 can be turned on / off by the changeover switch 8, and the lockup clutch 4 can be connected / disconnected according to the operator's judgment. .. When the load is increased while the lockup clutch 4 is manually engaged, the alarm device 9 is activated before the engine stalls, and the worker is in a state of disengaging the lockup clutch 4. Let us know.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3, reference numeral 5 denotes an agricultural tractor engine having a maximum rotation speed of 2500 to 3000 rpm, and the rotation of the crankshaft 11 is transmitted to the output shaft 12 via the torque converter 3. It is transmitted from the output shaft 12 to a transmission 13 having a plurality of transmissions and the like.

The torque converter 3 is a crankshaft 11 of the engine 5.
Alternatively, the front cover is fixed to the input shaft directly connected to the crankshaft 11, the pump impeller is connected to the front cover, the output shaft 12 is connected to the turbine runner, and the stator is supported to the transmission case via the one-way clutch. A lockup clutch 4 is arranged between the front cover and the turbine runner.

An oil passage 15 for supplying operating oil to the torque converter 3 and an oil passage 16 for supplying operating control oil to the lockup clutch 4 are provided between the pump 14 and the torque converter 3. Are controlled by the lockup control valve 2. The lockup control valve 2 is a modulation valve and has a 5-port switching valve 22 having an orifice and a feedback circuit and a shot valve 23. The switching valve 22 is operated by the control unit 1. When the solenoid is activated by energization to move the spool, pressure oil from the pump 14 is supplied to the lockup clutch 4 via the oil passage 16, and the lockup clutch 4 is supplied. Put 4 in contact.

The shot valve 23 is half-opened to fully-opened by the hydraulic pressure of the first pilot oil passage 23A and temporarily flows a large amount of oil when the pressure oil reaches just before the switching valve 22, and then the switching valve 22. To second pilot oil passage 23B
The hydraulic pressure sent via the valve changes from full open to half open, and the oil can be supplied to the lockup clutch 4 while throttled.

As a result, the lock-up clutch 4 is filled with oil in the first one-shot, and the time lag until the clutch is engaged is reduced. After that, the lock-up pressure gradually increases, and the lock-up connection is established. The shock of time is less. When the lockup control valve 2 operates and pressure oil is supplied to the lockup clutch 4, the lockup clutch 4 comes into close contact with the front cover, and the crankshaft 11 (the input shaft of the torque converter 3)
And the output shaft 12 are directly connected to each other to be in a lock-up contact state.
Conversely, when the pressure oil supply is stopped, the lockup clutch 4
Is separated from the front cover, and the lock-up contact state is released to disconnect it.

The crankshaft 11 is provided with an engine speed detection sensor 18 for detecting its actual speed A, and the output shaft 16 is provided with an output shaft speed detection sensor 19 for detecting its speed B. Are connected to the control unit 1. This control unit 1 has a built-in micro computer, and each detection sensor 1
Signals of the actual engine speed A and the output shaft speed B can be input from 8 and 19, respectively.

As a result, the ratio of the output shaft speed B to the actual engine speed A, that is, the difference (AB) between the actual engine speed A and the output shaft speed B causes the lockup clutch to be disengaged. The down rate C of the output shaft 12 can be calculated. This down rate C is set to 20%, for example,
If the down ratio of the output shaft 12 is less than that, the control unit 1 brings the lockup clutch 4 into the lockup contact state via the lockup control valve 2.

The control unit 1 includes an accelerator opening (throttle opening) detection sensor 6, a selection switch 7, an automatic / manual mode changeover switch 20, and a lockup clutch 4 which is connected / disconnected when switched to manual. The changeover switch 8 and the alarm device 9 are connected. The accelerator opening detection sensor 6 generates an engine rotation speed D (theoretical rotation speed) set corresponding to the amount of depression of the accelerator as a detection signal, and the engine actual rotation speed A of the crankshaft 11 (actually The down rate of the engine 5 in the lockup contact state can be calculated from the difference between the engine speed and the engine speed.

The selection switch 7 sets a plurality of down rates of the engine 5 and selects only one of them, and in the embodiment, it is divided into three types of down rates α, β and γ. α is 15-35%, down rate β
Is set to be 10 to 25%, and the down rate β is set to be different from each other in the range of 5 to 15%.
Becomes the down rate selected by the selection switch 7,
The control unit 1 changes the lockup clutch 4 to the lockup disengaged state via the lockup control valve 2.

The mode change switch 20 switches between an automatic mode in which the lockup control valve 2 is automatically operated based on information obtained from various sensors and a manual mode in which an operator can arbitrarily operate. Is. The changeover switch 8 is operated when the mode changeover switch 20 is selected as the manual mode. By turning on / off the changeover switch 8, the lockup control valve 2 is changed over to perform lockup. The clutch 4 is connected and disconnected. However, in the manual mode, it is preferable that the lock-up contact state is not set under the condition that the engine stalls.

The alarm device 9 emits an alarm sound or lights an alarm lamp. The mode change switch 20 is set to the manual mode and the change switch 8 is turned on to drive the tractor in the lock-up contact state. When the load increases during the operation, the operator is informed of this and urges the lock-up clutch 4 to be disengaged. When the work modes of the tractor are classified by weight and weight, for example, FIG.
As shown in FIG. 5, light work includes road running and rotary work, medium work includes middle and heavy towing work and scraping work, and heavy work includes front loader work and backhoe work. %, The down rate of the actual engine speed A is set to the down rate α for light work, the down rate β for medium work, and the down rate γ for heavy work.

Next, the lockup control of the torque converter 3 will be described with reference to the operation flowchart of FIG. The engine 5 of the tractor is started (step 1), and the torque converter 3 is operated via the crankshaft 11 (step 2). When the mode changeover switch 20 is in the automatic mode (step 3), the output shaft 12 rotates while causing slippage with respect to the crankshaft 11 by the operation of the torque converter 3, and the power can be transmitted to the transmission 13. The torque is transmitted by stepping on the accelerator to accelerate the rotation of the engine 5.

When the engine 5 is started and the tractor is started, the lock-up clutch 4 is disengaged, and the actual engine speed A and the output shaft speed detected by the engine speed sensor 18 and the output shaft speed sensor 19 are detected. The B signal is transmitted to the control unit 1 and read (steps 4, 5). Output shaft 1 while traveling or working on the road
When the load applied to 2 is small and the read output shaft speed B is about 80% or more of the actual engine speed A, that is,
When the down ratio C is 20% or less (step 6), the control unit 1 operates the lockup control valve 2 to bring the lockup clutch 4 into the contact state (step 7), and conversely, the load is large and the down ratio C is increased. If it is more than 20%, the lockup disconnection state is maintained and the reading of the rotation speeds A and B is repeated.

The contact operation of the lock-up clutch 4 is
The operating condition is that the output shaft rotational speed B is higher than the engine idling rotational speed (for example, 700 rpm), and if the output shaft rotational speed B is lower than the engine idling rotational speed, engine stall occurs when the contact state is established. When the lockup clutch 4 is in the contact state, the actual engine speed A and the output shaft speed B are the same, and the load is applied to the engine 5. The engine rotation speed D read by the accelerator opening detection sensor 6 changes according to the accelerator depression amount (step 8), and the reduction rate of the actual engine rotation speed A with respect to the engine rotation speed D at each time, that is, the down rate α. , Β,
When γ exceeds the set value (step 9), the control unit 1 operates the lockup control valve 2 to disengage the lockup clutch 4 (step 1
0) On the contrary, when the down ratios α, β and γ are small, the lock-up contact state is maintained and the reading of the rotation speeds A and D is repeated.

The down rates α, β and γ are selected by the selection switch 7
When the down ratio α is selected, if the actual engine speed A does not decrease by 15 to 35% relative to the engine speed D, the lockup disconnection state does not occur, and the down ratio β is selected. When is selected, the actual engine speed A is 10 to 25% of the engine speed D.
If it decreases, the lockup is disconnected. When the down ratio γ is selected, the lockup is disconnected only when the actual engine speed A decreases by 5 to 15% with respect to the engine speed D.

The present invention is not limited to the above embodiment, but can be variously modified. For example, the down rate C of the output shaft rotation speed B is uniform in all the work,
Similar to the down rate α, β, γ, this may be made different in each work, and the down rate α, β, γ may be changed in the above-mentioned range, or may be two steps or four steps or more. An electromagnetic proportional valve is used for the lockup control valve 2,
When the lock-up clutch 4 is operated to connect or disconnect, the hydraulic pressure in the lock-up clutch 4 may be gently raised or lowered to reduce the shock of the connection or disconnection.

[0026]

According to the present invention described in detail above, the control unit 1 has the down ratios α, β, γ of the actual engine speed A with respect to the engine speed D set by the accelerator opening.
Is connected to a switch 7 for selecting one of them in plural stages, and the lockup clutch 4 is set to be disengageable when the down ratios α, β and γ selected by the selection switch 7 are reached. Therefore, the connection / disconnection operation of the lock-up clutch 4 can be optimally controlled according to various types of light and heavy work, work efficiency can be improved, and engine stall can be prevented.

Further, since the control unit 1 is connected to the changeover switch 8 for manually changing over the connecting / disconnecting operation of the lockup clutch 4, it becomes possible for the operator to manually operate the load, so that the load is frequently changed. The operation suitable for working environment conditions can be performed. Further, since the control unit 1 is connected with an alarm device 9 for notifying that the down ratio C of the output shaft rotation speed B has become a predetermined value or less when the changeover switch 8 is in the lockup clutch contact operation, it is manually disconnected. Even in the contact operation, the engine stall can be reliably prevented.

[Brief description of drawings]

FIG. 1 is an overall explanatory view showing an embodiment of the present invention.

FIG. 2 is a table showing the same three types of modes.

FIG. 3 is a flowchart of the same operation.

[Explanation of symbols]

 1 control unit 2 lockup control valve 3 torque converter 4 lockup clutch 5 engine 6 accelerator opening detection sensor 7 selection switch 8 changeover switch 9 alarm device 11 crankshaft 12 output shaft 18 crankshaft rotation detection sensor A actual engine speed B output Shaft speed C Output down rate D Engine speed (accelerator opening) α Light work down rate β Medium work down rate γ Heavy work down rate

Claims (3)

[Claims] 1. A signal from a control unit (1) when a down ratio (C) of an output shaft speed (B) of a torque converter (3) with respect to an actual engine speed (A) falls below a predetermined value. A control device for a torque converter with a lockup in which a lockup clutch (4) of a torque converter (3) is operated via a lockup control valve (2), wherein the control unit (1) is an engine speed set by an accelerator opening degree. A selection switch (7) for setting a plurality of down rates (α), (β), (γ) of the actual engine speed (A) for (D) and selecting one of them is connected, and the selection switch (7 ) Is set so that the lockup clutch (4) can be disengaged when the selected down ratio (α) (β) (γ) is reached. The control device of the torque converter. 2. The tractor lock according to claim 1, wherein the control unit (1) is connected to a change-over switch (8) for manually changing over the connecting / disconnecting operation of the lock-up clutch (4). Control device for torque converter with up. 3. The alarm unit (9) for notifying that the down ratio (C) of the output shaft rotation speed (B) is below a predetermined value when the changeover switch (8) is in a lock-up contact operation. ) Is connected, The control device for the torque converter with lockup of the tractor according to claim 2.