JPS6218332A - Load controlling device for farming tractor - Google Patents

Abstract

PURPOSE:To improve operability by configurating a device in such a way that, while an auto mode is being effected, the mode is shifted to a hold mode if a hydraulic pressure lift lever and the like are actuated in a device where a swash plate of a hydraulic pump in a HST type speed change gear is operated depending on loads so as to control a vehicle speed automatically. CONSTITUTION:In a hydraulic pressure driven tractor, both a variable displacement hydraulic pump 39 and an auxiliary pump 53 are driven by an engine E, and a hydraulic motor 40 is driven by a discharge oil pressure from the pump 39. Discharge oil pressure from the auxiliary pump 53 is applied to both a hydraulic pressure control valve V which is linked with a speed change lever 9 and an engine mounted pump 43. And an operating cylinder C which controls a swash plate 39a of the said pump 39 is controlled by means of controlling both the valve V and solenoid valves V1 through V5/ In this case, while an automatic load control is in operation, each of the solenoid valves V1 through V5 is controlled in such a way that an auto mode is switched over to a hold mode when a hydraulic pressure lift lever is actuated upward, and the suto mode is switched over to a standby mode when the lever 9 is operated while the hold mode is being effected.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention drives an agricultural tractor by a transmission equipped with an HST type transmission, thereby enabling continuously variable speed and reducing the number of revolutions of the engine. etc. to detect the tractor load, and use the feedback signal from the load to detect the H3T
The present invention relates to a technology for automatically operating a hydraulic pump swash plate of a type transmission to automatically increase or decrease vehicle speed.

(b) Prior art A known technology that used the H3T type transmission as a tractor transmission and made it possible to automatically increase/decrease the working speed was the technology disclosed in Japanese Patent Application Laid-open No. 83619/1983. .

(c) Problems to be Solved by the Invention An object of the present invention is to provide a tractor equipped with an H3T type transmission to enable continuously variable speed, and to provide an operating cylinder C for rotating a swash plate of a hydraulic pump. The operating cylinder C is configured to turn on and off the solenoid valve in response to a feedback signal of an increase or decrease in load detected by an increase or decrease in engine speed.
This is a device that turns off, expands and contracts, and changes the angle of the swash plate of the H3T type transmission to control the speed corresponding to the load. be.

In other words, in a field with a wide headland, the machine can be automatically controlled so that it can continue to work without slowing down while working, and then lower the work machine at that speed after turning. At the edge of the field, a "hold" mode is provided to memorize and maintain the speed at which the work equipment was raised just before it was raised, and the system is configured so that the "hold" mode is immediately activated by rotating the hydraulic lift lever in the raising direction. However, when the field is narrow or when working in paddy fields, it is not possible to keep going straight at the same speed as when working in a straight line, and it is necessary to reduce the speed once. In the present invention, when the shift lever is operated and rotated when it is necessary to further shift from the state in which the hydraulic lift lever 60 is turned up to be in the "hold" mode, the "hold" mode is canceled. Then, the system is configured to shift to a "standby" mode in which manual shifting is possible using the hydraulic control valve (2).

Furthermore, since the hydraulic lift lever is not raised and rotated when the work equipment is lowered and is traveling for work, the control is
``Auto'' mode, and in the ``Auto'' mode, even if the gear shift lever is rotated, the automatic/manual switching solenoid valve S
1 is closed, the hydraulic control valve V does not operate and the gear shift does not return to neutral. However, because the shift lever is often operated to neutral due to danger, in the present invention, Shift "Auto" mode to "Standby" mode,
It is configured to enable the operation of the hydraulic control valve V and stop the vehicle from traveling.

(d) Means for solving the problem The object of the present invention is as described above. Next, the structure for achieving the object will be explained.

The swash plate of the hydraulic pump of the HS 7-type transmission is configured to be rotated by an operating cylinder, and the expansion and contraction of the operating cylinder can be controlled by operating a solenoid valve for automatic control or a manual hydraulic control valve V. In this configuration, when working under automatic load control, the "auto" mode is shifted to the "hold" mode by raising the hydraulic lift lever, and furthermore, by operating the shift lever in the "hold" mode, the " The "hold" mode is canceled and the "standby" mode is set, allowing operation using the gear shift lever.

In addition, even when working in the "auto" mode, by operating the gear shift lever to the neutral position, the "auto" mode is shifted to the "standby" mode, and the swash plate 3 of the hydraulic pump 39
9a is rotated to the neutral position by hydraulic control valve (2).

(e) Embodiments and Functions The objects and structure of the present invention are as described above. Next, the structure of the embodiments shown in the attached drawings and the invention will be explained in detail.

Fig. 1 is a hydraulic circuit diagram of the hydraulically driven tractor of the present invention, Fig. 2 is a control operation diagram showing the working speed and the opening/closing state of the solenoid valve group, and Fig. 3 is a diagram showing the transition possible relationship between each control mode. It is.

The hydraulic circuit configuration of the present invention will be explained with reference to FIG. A
is an H3T type transmission, which transmits the rotation of the engine E through a hydraulic pump shaft 7 to drive a hydraulic pump 39 and an auxiliary hydraulic pump 53. A hydraulic motor 40 is operated by pressure oil discharged from the hydraulic pump 39.

In addition, the pressure oil discharged by the auxiliary hydraulic pump 53 is passed through the relief valve 54 to the pressure oil boat a of the hydraulic control valve (■).
It is sending oil to. Further, pressure oil from an engine-mounted pump 43 that discharges another high-pressure oil is also sent to the pressure oil boat via the electromagnetic valve S6.

The solenoid valve S6 is opened only in an emergency when the main clutch device 55 between the engine E and the hydraulic pump shaft 7 is disconnected and the discharge of pressure oil from the auxiliary hydraulic pump 53 is stopped. It is linked to stepping. Even if the main clutch device 55 is disconnected, the swash plate 39a can be operated using the pressure oil from the engine-mounted pump 43, which is discharging pressure oil.

The engine-mounted pump 43 normally raises and lowers a working machine mounted on a tractor and supplies pressure oil for power steering.

With this configuration, when the main clutch device 55 is disengaged,
Although the hydraulic pump shaft 7 does not rotate and the auxiliary hydraulic pump 53 does not discharge pressure oil, the swash plate 39a of the hydraulic pump 39 can be rotated by the pressure oil from the engine-mounted pump 43.

Furthermore, since the engine-mounted pump 43 is a high-pressure pump fixed to the side of the engine, high-pressure oil is introduced, the swash plate 39a can be operated at high speed, and emergencies can be dealt with quickly and safely. The solenoid valve S6 is opened and closed in conjunction with the depression of the tractor's main clutch pedal 57. Normally, when the main clutch device 55 is connected, the solenoid valve S6 is closed and the auxiliary hydraulic pressure is The operating cylinder C is operated only by the pressure oil from the pump 53.

In this embodiment, the S
A 5 Mi solenoid valve of 85 from 1 is provided, and the solenoid valve S1 shuts off the oil path to the hydraulic control valve ■, and the other 4 sets of solenoid valves from 82 to 85 block the pressure oil to the operating cylinder 〇. This controls oil supply and stoppage.

When the vehicle speed is not automatically controlled based on the load, the solenoid valve S1 is fixed in an open state, and the solenoid valves S2, S3, S4, and S5 are fixed in a closed state.

The solenoid valves S2 to 85 are operated by electric signals only during automatic gear shift adjustment.

That is, in the case of automatic transmission control, pressure oil is converted into hydraulically controlled pulp V.
The solenoid valve S1 that was sending pressure to the thin side of the operating cylinder 〇 closes, the hydraulic control valve ■ stops operating, and the solenoid valve S3 opens and closes the pressure oil to the thin side of the operating cylinder 〇. The opening and closing are performed by the solenoid valve S2. The return oil from the oil chamber of the operating cylinder C is controlled by separate solenoid valves S4 and 85.

That is, the opening and closing of the solenoid valve S3 and the opening and closing of the solenoid valve S4 are performed at the same time, and the opening and closing of the solenoid valve S2 and the opening and closing of the solenoid valve S5 are performed at the same time, so that the operation cylinder C is expanded and contracted smoothly.

In addition, in this embodiment, the solenoid valves S4 and S5, which open and close the drain circuit on the return oil side of the operating cylinder C during automatic control, can be opened and closed intermittently by pulses, so that the operating cylinder C can be moved. Slow speed, swash plate 3
The rotating speed of 9a can be adjusted to change the feeling of shifting.

Next, the control will be explained with reference to the control state diagram in FIG. 2 and the diagram in FIG. 3 showing the shiftable relationships between the control modes. Various signals are sent to a feed bank signal and a controller M that compares and calculates set values.

These include the depression of the main clutch pedal 57, the rotation angle of the accelerator lever 58, the operation of the manual/automatic changeover switch 59, the variation in the rotational speed of the engine E, the rotation angle of the hydraulic lift lever 60, etc.

In addition, a work setting switch 61 for selecting the work state desired by the operator can be used to select "rotary tilling slow" or "rotary tilling slow".
You can select from "fast rotary plowing", "slow plowing", "fast plowing", "plow", etc. These R
According to the working conditions from β1 to R5, the rotation angle of the swash plate 39a of the hydraulic pump 39, that is, the maximum traveling speed, is set from β1 to R5. In contrast, the current swash plate 39a
The rotation angle is input as β from the detection device 42. Further, the rotational position of the gear shift lever 9 is also determined manually by the detection device 41 as α.

Among the numbers indicating the operation of the solenoid valve group in FIG. 2, 1 indicates the rONJ state of the solenoid valve, and 0 indicates the [0FFJ state of the solenoid valve.

In "standby" mode, all solenoid valves for automatic control are "closed".
The solenoid valve S1 for automatic/manual switching is "open", and the speed can be changed by the speed change lever 9. In "auto" mode, the solenoid valve S for manual/automatic switching closes and becomes "auto", and has three positions: "increase", "hold", and "decelerate", and in "increase", solenoid valve S3 84 is opened, solenoid valves S2, S3, s4, and s5 are closed in "hold" mode, and solenoid valves S2 and 85 are opened in "deceleration" mode.

The "emergency" mode is when the main clutch device 55 is disconnected, the solenoid valve s6 is opened, and high pressure oil from the engine-mounted pump 43 is sent to the hydraulic control valve V or the solenoid valve group, and the auxiliary clutch device 55 is disconnected. This compensates for the drop in hydraulic oil pressure due to the stoppage of the hydraulic pump 53.

With this configuration, when the operator sets a desired speed using the work setting switch 61, the set values from R1 to R5 are determined, and the angle of the swash plate 39a is determined to reach these values. be. In this state, when the load on the work equipment becomes large and the rotation of the engine E decreases, a deceleration signal is issued and the engine is "held" at a certain deceleration position, and when the rotation of the engine E returns, it returns to the original speed. If the rotation of the engine E further decreases, the speed is further reduced repeatedly.

The rotation of the tractor engine E is transmitted via the main clutch device 55 to the hydraulic pump shaft 7 of the hydraulic pump 39.

Further, the operating cylinder C is composed of a cylinder case 38 and a piston 36, and the tip of the piston 36 is configured to rotate the swash plate rotation wheel 10 of the swash plate 39a of the hydraulic pump 39. That is, a swash plate rotation arm 37 is fixed to the right end of the swash plate rotation shaft 10, and the tip of a piston 36 is fixed to the swash plate rotation arm 37.

Also, let me explain the configuration of the hydraulic control valve ■.

The operation spool 26 and the feedback spool 27 constitute a double-structured spool within the valve case.
The operating spool 26 is slid by the rotation of the speed change lever 9, and is switched from a neutral position to a speed increasing or decelerating position between the feedback spool 27, which is not moving yet, and the boat. As a result, the operating cylinder C is expanded and contracted, and the swash plate rotation shaft 1 of the swash plate 39a of the hydraulic pump 39
0 rotates, this causes the feedback spool 27 of the hydraulic control valve (2) to slide in the neutral direction, returning the operating spool 26 to the neutral position. Reference numerals 34 and 35 designate check valves that ensure the holding state of the operating cylinder 0 and prevent the swash plate 39a from rotating and changing its speed due to external impact. Further, 41 is a detection device for detecting the set position of the speed change lever 9.

FIG. 4 is a control flowchart of the load control device of the present invention;
FIG. 5 is a diagram showing each control signal input to the controller M. The present invention will be explained in detail with reference to FIGS. 4 and 5. FIG.

When the manual/automatic changeover switch 59 is set to "manual", the automatic/manual changeover solenoid valve s1 opens, enabling speed changes using the hydraulic control valve ■, and all solenoid valves 82 to 85 for automatic control are closed. It becomes "oFF".

Even when the manual/automatic changeover switch 59 is set to automatic, there is a mode in which the shift lever 9 and the hydraulic control valve V can be operated, which is the same as the "manual" mode, and this is the "standby" mode.

Furthermore, within the "auto" mode, there are "acceleration" mode, "deceleration" mode, and "holding" mode.

In the case of "speed increase" mode, "deceleration" mode, and "hold" mode, the automatic/manual switching solenoid valve S1 is turned ON, the oil passage to the hydraulic control valve V is closed, and the 85
Accordingly, the operating cylinder C is operated.

In the "Hold" mode, as shown in the flowchart in Figure 4, when the brake pedal is depressed, the accelerator lever is
8 to the idling position, when the main clutch pedal 57 is depressed, when the hydraulic lift lever 60 is raised and rotated, the automatic mode of the "acceleration" mode or "deceleration" mode is The state that has been set will shift to "hold" mode.

In the "hold" mode, all of the automatic control solenoid valves S1 and 85 are closed, the operation cylinder 0 is held in the previous state, and the position of the swash plate 39a is also maintained in the previous state. Therefore, when the brake pedal, accelerator lever 58, main clutch pedal 57, and hydraulic lift lever 60 are returned to their original positions, the maintained speed returns to the "auto" mode.

When going around the edge of the field, the hydraulic lift lever 60 is used to raise the work equipment, so it enters the "hold" mode. However, when the machine slows down, goes around, and then tries to increase the speed again after the end of going around. Since the "hold" mode continues during the rotation, the speed remains the same, and if you want to change gears, first set the manual/automatic changeover switch 59 to manual.
This means that you will have to shift gears.

In the present invention, since it is troublesome to manually/automatically switch 59 to manually switch the switch 59, the shift lever 9 is rotated while the work equipment is in the "hold" mode, such as by raising the work equipment. When operated, the "hold" mode shifts to the "standby" mode, the shift lever 9 becomes operable, and the hydraulic control valve V is activated so that the speed is at the position where the shift lever 9 is rotated. However, it is configured to move the operating cylinder C and the swash plate 39a.

When the hydraulic lift lever 60 is lowered from the "standby" mode to the lowered position, the "automatic" mode is returned again.

In addition, while working in the "speed increase" mode or "deceleration" mode of the "auto" mode, the brake pedal, main clutch pedal 57, accelerator lever 58, hydraulic lift lever 6
If you operate 0, you will enter the "hold" mode, and if you further move the gear shift lever 9, you will enter the "standby" mode.
However, if you do not perform the prerequisite operation to enter the "hold" mode, you can directly shift the shift lever 9.
Even if you try to change gears by operating the , it will be ignored while in "auto" mode. However, this may cause an accident, so in the present invention, the shift lever 9 is moved during the "auto" mode, especially to the neutral position, so that there is no movement to stop the aircraft. Only if “
The "automatic" mode was switched to the "standby" mode, the hydraulic control valve V was enabled to operate, the operating cylinder C was moved to the neutral position, and the aircraft was stopped.

However, this control is performed when the shift lever 9 is rotated to the neutral position, and in the case of only a shift operation, the hydraulic control valve ■ cannot be operated as before, and the "auto" mode is disabled. It continues. The "automatic" mode shifts to the "standby" mode only when the gear shift lever 9 is rotated to the neutral position.

(F) Effects of the Invention Since the present invention is constructed as described above, it has the following effects.

First, in the present invention, when the brake pedal, main clutch pedal 57, hydraulic lift lever 60, accelerator lever 58, etc. are temporarily operated during work, the previous speed is "held". Therefore, the next time you return to normal working conditions, you can immediately return to the previous speed, so there is no need to reset the settings, and you can quickly return to the original working speed.

Secondly, even when making rounds at the edge of the field, the speed is maintained at the same speed as before raising the work equipment, so if the speed is too high for making rounds, the operator must reduce the speed. It is troublesome to turn the manual/automatic changeover switch 59 to manual and then operate the gear shift lever 9 each time, but in the present invention, "hold"
When the gear shift lever 9 is rotated in the mode, the mode shifts to the "standby" mode, and the manual/automatic changeover switch 5
Since the shift lever 9 can be operated without operating the gear shift lever 9, it is possible to save time and effort during turning.

Third, the brake pedal or main clutch pedal 5 may be moved to the "hold" mode while working in the "auto" mode.
7, the accelerator lever 58, or the hydraulic lift lever 60, when the gear shift lever 9 is rotated to neutral,
Prioritizing this, the automatic control is set to "standby" mode, and the swash plate 39a is set to neutral, so that in an emergency, the manual/automatic changeover switch 59 is not operated, but the shift lever 9 can be directly operated. , the aircraft can be stopped.

[Brief explanation of drawings]

Fig. 1 is a hydraulic circuit diagram of the hydraulically driven tractor of the present invention, Fig. 2 is a control operation diagram showing the working speed and the opening/closing state of the solenoid valve group, and Fig. 3 is a diagram showing the transition possible relationship between each control mode. , FIG. 4 is a control flowchart of the load control device of the present invention, and FIG. 5 is a drawing showing each control signal input to the controller M. A... H3T type transmission 'C... Operation cylinder M... Mission case ■... Hydraulic control valves Sl, S2. S3. S4. S5. S6...Solenoid valve 9...Speed lever 26...Operation spool 27...Feed hack spool 34.35...Chesokhalbu 39...Hydraulic pump 39a...Hydraulic pump swash plate 40...Hydraulic motor

Claims (2)

[Claims] (1). The swash plate of the hydraulic pump of the HST type transmission is configured to be rotated by an operating cylinder, and furthermore, the expansion and contraction of the operating cylinder is configured to be controllable by operating a solenoid valve for automatic control or a manual hydraulic control valve. When working with automatic load control, the "auto" mode is shifted to the "hold" mode by raising the hydraulic lift lever.
Furthermore, in the "hold" mode, by operating a gear shift lever, the "hold" mode is canceled and the mode is set to a "standby" mode, which can be operated by the gear shift lever. (2). Even during work in the "automatic" mode described in claim 1, by operating the gear shift lever to the neutral position, the "automatic" mode is shifted to the "standby" mode, and the hydraulic pump is turned off. A load control device for an agricultural tractor, characterized by rotating a plate to a neutral position using a hydraulic control valve.