JP3009785B2 - PTO transmission mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PTO shaft transmission mechanism which projects from a rear part of a tractor in a working vehicle and transmits power to a mounted working machine.

[0002]

2. Description of the Related Art Conventionally, a transmission mechanism of a PTO shaft of a tractor is mostly constituted by a mechanical transmission mechanism. Therefore, if the PTO shift is performed insensitively, there is a problem that an overload occurs, the safety pin is damaged, and noise is generated due to the operation of the safety clutch on the working machine side. To solve this problem, an electronically variable PTO
Although a mechanism was proposed, the following problems occurred in the electronic transmission mechanism when the transmission was mechanical.

[0003]

That is, since the mechanism is a mechanical step-variable transmission mechanism, the engine speed is increased or decreased except for the set number of revolutions, so that the vehicle speed of the tractor changes. It will be lost. As a result, a decrease in work efficiency could not be avoided. In addition, in a working machine, such as a mower device, in which the peripheral speed of the cutter blade is required to be constant, if the engine speed is reduced in consideration of noise in a house or a golf course, the blade speed becomes lower. There was a problem that the sharpness was reduced. Also P
In addition to the continuous load applied during operation, a peak torque of 10 times or more of the rated torque may be applied to the TO shaft, and the peak torque may damage the PTO transmission mechanism and shorten the life of the tractor. There were many defects. The present invention solves such disadvantages of the prior art.

[0004]

The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described. In claim 1, the PTO shaft 1 of the working vehicle
An HST type transmission is interposed in a transmission circuit for transmitting power to the PTO shaft so that the rotation of the PTO shaft can be continuously variable.
In addition, the PTO shaft can be rotated forward and backward, and the PTO shaft 1
The maximum output horsepower at the time of reverse rotation is smaller than the maximum output horsepower at the time of normal rotation.

In a second aspect, the PT according to the first aspect is provided.
In the O transmission mechanism, the output or input of the HST transmission is limited based on the result of calculating the input rotation speed or output rotation speed of the HST transmission and the hydraulic pressure of the HST transmission.

According to a third aspect of the present invention, a PTO shaft 1 for a working vehicle is provided.
An HST-type transmission is interposed in a transmission circuit that transmits power to the PST shaft, and the rotation of the PTO shaft can be continuously changed. When the HST-type transmission is operated in a neutral state, the clutch is disengaged.

In a fourth aspect, the PT according to the first aspect is provided.
In the O transmission mechanism, when the PTO shaft 1 is increased from the stop or the vicinity of the stop state to the rotation speed set by the rotation speed setting means, the hydraulic pressure of the HST type transmission is rotated so that the hydraulic pressure does not exceed the set hydraulic pressure. The number is controlled.

[0008]

Next, the operation will be described. The PTO shaft 1 of the present invention projects from the rear surface of the tractor, and power is transmitted from the PTO shaft 1 to the work equipment via a universal joint. The hydraulic pump P is rotated by the engine E of the tractor via the input shaft 14, and the oil discharged from the hydraulic pump P is supplied to the hydraulic motor M via a closed circuit. The hydraulic motor M is rotated by the pressure oil. The swash plate provided on the hydraulic pump P is operated by the swash plate operation cylinder 5, the discharge pressure is changed, the rotation of the PTO shaft 1 is steplessly varied, and the PTO shaft 1 is rotated forward and backward. The swash plate operation cylinder 5 is switched by the swash plate operation valve 4 and the solenoids solA and solB.

[0009]

Next, an embodiment will be described. FIG. 1 shows a PT of the present invention.
FIG. 2 is a flow chart for setting the maximum output horsepower at the time of reverse rotation to half of the maximum output horsepower at the time of normal rotation and controlling the O transmission mechanism, and FIG. FIG. 4 is a flowchart showing a configuration in which the rotational speed of the PTO shaft 1 is set lower than the set rotational speed PR. FIG. 4 is a flowchart of an embodiment in which the rotational speed of the PTO shaft 1 is set lower than the set rotational speed PR. FIG. 6 is a flowchart of a control for restricting an output or an input based on a calculation result of a rotational speed, an output rotational speed, and a hydraulic pressure. FIG. 6 is a flowchart of a control for limiting an output by a rack position sensor and an output rotational speed. 7 is a flowchart of control for reducing the number of rotations of the hydraulic motor M when the torque has to be secured when the output is at or near the limit, 8, during driving the working machine via the HST type transmission apparatus, when OFF the rotation of the PTO shaft 1,
5 is a flowchart of control for turning off a clutch 2.

FIG. 9 is a flowchart of control in which a neutral stop valve 3 for short-circuiting a closed circuit is provided as shown in FIG. 1 instead of providing a clutch 2 between the hydraulic motor M and the PTO shaft 1, and FIG. FIG. 11 is a flowchart of a control for disconnecting the clutch 2 and the neutral stop valve 3 when the rotation of the engine E is stopped. FIG. 11 shows a clutch provided on one or both of the input side and the output side of the HST type transmission. FIG. 12 shows a state in which the reverse valve 8 is interposed in the closed circuit of the HST transmission, and the forward / reverse switching can be performed by switching the reverse valve 8 without operating the swash plate setting lever 19. FIG. 13 is a flow chart of forward / reverse switching by the reverse rotation valve 8, and FIG.
6 is a drawing of the PTO operation lever 23 and the detection switches 24 and 25 in the case of forward / reverse switching according to FIG.

FIG. 15 shows a solenoid sol of the reversing valve 8.
FIG. 16 is a flowchart of a control for driving the C by pulse driving to change the rotation speed of the PTO shaft 1 by changing the duty ratio of the pulse, and FIG. 16 shows the set load set by the engine load setting device and the rack position of the governor. FIG. 17 is a flowchart for controlling the rotation speed of the PTO shaft 1 by detecting the load and operating the swash plate of the HST type transmission with the load, and FIG. 17 shows that the swash plate is instructed to rotate forward from neutral to forward or reverse. FIG. 18 is a flow chart for controlling the clutch 2 to be engaged before the output shaft 17 of the hydraulic motor M starts rotating, and FIG. In doing so,
FIG. 19 is a flowchart of control for preventing the pressure of the HST transmission from exceeding the set pressure, and FIG.
When the clutch 2 is disposed between the output shaft 17 and the PTO shaft 1, when the PTO shaft 1 is rotating, the rotation speed of the output shaft 17 is substantially equal to the rotation speed of the PTO shaft 1. It is a flowchart figure of the control which made the clutch 2 be connected for the first time.

Referring to FIG. A swash plate is provided on the hydraulic pump P that drives the input shaft 14 of the hydraulic pump P by the engine E, and a swash plate angle detection sensor 6 that detects the angle of the swash plate is provided. A swash plate operating cylinder 5 for operating the swash plate is provided.
Is switched by the swash plate operation valve 4 and supplied to the swash plate operation cylinder 5. The swash plate operation valve 4 is opened and closed by solenoids solA and solB.

A closed circuit is formed between the hydraulic pump P and the hydraulic motor M, and the clutch 2 is interposed between the output shaft 17 from the hydraulic motor M and the PTO shaft 1. Further, a check relief valve 28 is interposed in a circuit for short-circuiting a closed circuit connecting the hydraulic pump P and the hydraulic motor M, and when a negative pressure occurs in the closed circuit, the pressure oil from the charge pump 10 Is provided. 11
Is a charge relief valve. Further, a neutral stop valve 3 for short-circuiting a closed circuit is configured, and a solenoid solC is provided.
It is configured to open and close.

A safety check valve 15 is provided in a circuit for short-circuiting a closed circuit, and a safety relief valve 16 is provided. A pressure sensor 18 is provided between the safety check valves 15. An engine rotation sensor 12 for detecting the rotation speed of the input shaft 14 is arranged near the input shaft 14, and an output rotation speed sensor A is arranged near the output shaft 17. Further, a PTO rotation speed sensor B is disposed near the PTO shaft 1.

The various sensors arranged as described above, the engine rotation sensor 12, the swash plate angle detection sensor 6, and the oil pressure sensor 18
Signals from the output rotation speed sensor A and the PTO rotation speed sensor B are transmitted to the central processing unit CPU. In addition, a rotation angle signal of the swash plate setting lever 19 is transmitted from the transmission lever sensor 7 to the central processing unit CPU. The signals from these sensors are calculated, and outputs are transmitted to the solenoids solA and solB, the solenoid solC, and the clutch relay 20 of the clutch 2.

In FIG. 2, the maximum output horsepower at the time of reverse rotation is
A configuration in which the output horsepower during normal rotation is controlled to about half will be described. The rotation speed X of the output shaft 17 is read by the output rotation speed sensor A. Next, the pressure Y is read by the pressure sensor 18. The multiplier of the rotation speed X and the pressure Y becomes the output horsepower. Next, the position of the swash plate setting lever 19 is read by the swash plate setting lever sensor 7 and is set as the angle Z. Next, the swash plate angle detection sensor 6
, The actual swash plate angle is read, and this angle is set to W. Solenoid solA ・ sol until both are equal
Control B. Next, it is determined whether or not the angle Z of the swash plate setting lever 19 is in the reverse direction.
The value of pressure Y = PS is half of the maximum output SPS.
The solenoid solB is controlled so as to be 5.

Next, in FIGS. 3 and 4, the rotational speed of the PTO shaft 1 is set to a set rotational speed PR depending on the rotational speed of the engine E.
Control that is lower than the above will be described. First, the engine speed r is read by the engine speed sensor 12. Then P
The rotational speed Pr of the PTO shaft 1 is read by the TO rotational speed sensor B. Next, the set rotational speed SRS of the engine E is read. Next, the set rotational speed SPr of the PTO shaft 1 is read. Next, the engine speed r is lower than the set speed SRS of the engine E, and the speed Pr of the PTO shaft 1 is changed to the set speed PRS.
If the rotation speed Pr of the PTO shaft 1 is not equal to R and is lower than the set rotation speed SRS, the swash plate is rotated to the high speed side. Conversely, the rotational speed Pr of the PTO shaft 1 is equal to the set rotational speed S.
If it is larger than RS, the swash plate is moved to the lower speed side.

In the control of FIGS. 3 and 4, the PTO shaft 1
Is lower than the set rotation speed depending on the rotation speed of the engine E. The engine E maintains the rotational speed of the PTO shaft 1 at a set rotational speed from a high rotational speed to a certain rotational speed, and when the rotational speed falls below the preset rotational speed, the PTO shaft 1 increases in proportion to the rotational speed of the engine E. The number of revolutions was reduced. The state of the above control is shown in FIG.

FIG. 5 shows a flowchart of control for limiting the output or the input based on the calculation results of the input rotation speed, the output rotation speed, and the hydraulic pressure. The engine speed r is read by the engine speed sensor 12. Next, the pressure P of the closed circuit is read by the pressure sensor 18. Next, the value ip of the output setting device or the value of the input setting device OP is read. Next, it is determined whether or not ip (or OP) is substantially equal to r × P. If equal, swash plate control is OK. If the set value is larger, the swash plate is moved to the high speed side. Ban. According to this flowchart, output limitation or input limitation is performed based on the calculation result of the input rotation speed or output rotation speed and the hydraulic pressure of the HST transmission.

Next, referring to FIG. 6, a description will be given of a control for reducing the number of revolutions of the hydraulic motor M when the torque has to be ensured when the output is at or near the limit. First, the rotational speed r of the engine E is read. Next, the rack position ER is read by a rack position sensor arranged in the governor portion of the engine E. Next, the set value ip of the input setting device is read. It is determined whether ip <r × ER. If this condition is satisfied, the swash plate movement is OK, but if not, the swash plate movement to the high speed side is prevented.

Next, referring to FIG. 7, a description will be given of a control for reducing the number of revolutions of the hydraulic motor M when the torque has to be ensured when the output is at or near the limit. In this case, in the control flowcharts of FIGS. 5 and 6, the solenoid solA is slightly operated at the final stage to deliberately reduce the rotational speed of the hydraulic motor of the HST type transmission.

Next, referring to FIG. 8, a description will be given of a control for turning off the clutch 2 when the rotation of the PTO shaft 1 is turned off while the work implement is being driven via the HST type transmission. Swash plate setting lever sensor 7 for detecting the angle of swash plate setting lever 19
It is determined whether or not the vehicle is in the neutral position, and if not, the clutch relay 20 that operates the clutch 2 is turned on.
Put as. When the swash plate setting lever 19 is rotated to the neutral position, the clutch relay 20 is turned off and the clutch 2 is disconnected. When a clutch is separately provided between the engine E and the hydraulic pump P, the clutch is turned off.
And

FIG. 9 explains the control in the case where the clutch 2 is not provided between the hydraulic motor M and the PTO shaft 1, but the neutral stop valve 3 for short-circuiting the closed circuit is provided as shown in FIG. In this case, the rotation angle of the swash plate setting lever 19 is detected by the swash plate setting lever sensor 7, and when the HST type transmission is operated neutral, the solenoid solC is turned on and the neutral stop valve 3 is opened. Then, the closed circuit is short-circuited. Thus, the rotation of the hydraulic motor M stops.

In FIG. 10, even when the rotation of the engine E is stopped, this is detected by the engine rotation sensor 1.
2, and the rotation of the PTO shaft 1 is stopped by the clutch 2 or the neutral stop valve 3. In other words, the rotation of the PTO shaft 1 is stopped by the clutch 2 and the neutral stop valve 3 when the swash plate of the HST type transmission becomes neutral or when the engine E is stopped.

In FIG. 11, the clutch 9 is provided on one or both of the input side and the output side of the HST type transmission.
It is the drawing in the state where 2 was provided. If such a clutch is not provided, power loss occurs only by rotating the hydraulic pump P from the engine E.
When the neutral stop valve 3 is mounted, the PTO
If the shaft 1 cannot rotate, the pawl clutch will not fit,
It is impossible to mount the clutch, but as described above, providing the clutch 2.9 on one or both sides of the HST type transmission can solve such a problem.

In FIG. 12, the swash plate setting lever 19 is provided in the closed circuit of the HST type transmission by interposing the reverse rotation valve 8.
3 shows a hydraulic circuit which enables switching between forward and backward movement by switching the reverse rotation valve 8 without performing the operation described in FIG. FIG.
Is a flow chart of forward / reverse switching by the reverse valve 8;
FIG. 14 is a drawing of the PTO operation lever 23 and the detection switches 24 and 25 in the case of forward / reverse switching by the reverse rotation valve 8.
In this embodiment, when the PTO operation lever 23 is rotated back and forth, the detection switches 24 and 25 detect the front and rear directions, and first, the reversing valve 8 is switched. The board tilts.

FIG. 15 shows a solenoid sol of the reversing valve 8.
6 is a flowchart of control for driving a pulse E and changing the duty ratio of the pulse so that the rotation speed of the PTO shaft 1 can be changed. In this case, PT
The rotational speed or is read by the O rotational speed sensor B, and then P
The set rotational speed Sr is read by the TO rotational speed setting device. Then, the magnitude of both is determined, and the solenoid solE is turned ON-O.
The shift of the hydraulic motor M is performed by changing the duty of the pulse signal for performing the FF.

FIG. 16 shows the load detected by the set load set by the engine load setter and the position of the governor rack, and the swash plate of the HST type transmission is operated by the load to change the rotation speed of the PTO shaft 1. It is a flowchart drawing which controls. The rack position of the governor is compared with the set load of the engine E. When the load is close to the set load, the rotation speed of the PTO shaft 1 is reduced. The numbers go up.

FIG. 17 is a flow chart for controlling the clutch 2 to be connected before the output shaft 17 of the hydraulic motor M starts rotating when the swash plate is instructed to rotate from neutral to forward or reverse. . That is, when the swash plate setting lever 19 is operated to the neutral position, the clutch relay 20 and the clutch 2 turn off the power. Next, when the swash plate setting lever 19 is operated to perform forward rotation or reverse rotation, first, the clutch relay 20 is turned on and the clutch 2 is connected. Next, the solenoids solA and solB are excited, and The operation of rotating the plate is delayed by a delay timer.

FIG. 18 shows that when the PTO shaft 1 is stopped or near the stopped state and rises to the set rotation speed, the HST
4 is a flowchart of control for preventing the pressure of the transmission from exceeding a set pressure. First, it reads that the swash plate is at or near the neutral position, and then reads the setting HST transmission SP of the pressure setting device. Next, the value P of the pressure sensor 18 is read. Next, the PTO setting rotational speed Sr is read. Next, the PTO shaft 1 is detected by the PTO rotation speed sensor B.
Read the rotation speed of. By comparing the magnitudes of the Sr and r, P
And SP size, solenoid solA / solB
ON / OFF is controlled. With this, PT
When the rotation speed of the O-shaft 1 reaches the set rotation speed, HS
The control is performed so as not to exceed the set hydraulic pressure of the T-type transmission.

FIG. 19 shows a case where the clutch 2 is disposed between the output shaft 17 and the PTO shaft 1 and the rotation speed of the output shaft 17 and the rotation speed of the PTO shaft 1 are substantially equal when the PTO shaft 1 is rotating. It is a flowchart drawing of the control which made the clutch 2 connect for the first time when it became equivalent. That is, when the swash plate setting lever 19 is operated to the neutral position, the clutch 2 is disengaged, and the swash plate setting lever 19 is operated to the rotating side while the PTO shaft 1 is still rotating by inertia. And the clutch 2 is connected by the clutch relay 20, but the clutch 2 is not connected unless the inertial rotation speed of the PTO shaft 1 and the rising rotation speed of the output shaft 17 become the same. .

[0032]

As described above, the present invention has the following advantages. In other words, the PTO shaft 1 is usually designed to work in the normal rotation state in many cases, and the reverse rotation is necessary only in special cases such as inspection, repair, and cleaning. It is often the direction. Therefore, when transmitting a large torque in reverse rotation,
Work equipment is often damaged. In the present invention, the torque at the time of reverse rotation is configured to be smaller than the torque at the time of normal rotation, so that the working machine is not damaged.

In addition, when the engine E is not rotating at a sufficient speed, the rotation speed of the PTO shaft 1 is increased more than necessary to cause engine stall or when the engine is overloaded. This eliminates the need to continue the operation while raising the black smoke, and makes it possible to instruct the number of revolutions of the PTO shaft 1 corresponding to the output of the engine E.

Further, since the present invention is constructed as in claim 3, the HS
Even when the rotation of the PTO shaft 1 is stopped with the T-type transmission being in a neutral state, the rotation of the hydraulic pump P is not continued, so that a power loss for idling the hydraulic pump P is avoided, and the hydraulic pump P is prevented from rotating. It was possible to improve the durability of P.

Further, since the present invention is constructed as in claim 4, the PT
In the course of increasing the rotation speed of the O-shaft 1 to the set rotation speed,
Due to the convergence of control, the hydraulic pressure of the HST-type transmission may fluctuate between high and low. However, by configuring as in the present invention, the solenoids solA and solB are controlled so that the hydraulic pressure does not exceed the set hydraulic pressure. It became possible.

[Brief description of the drawings]

FIG. 1 is a hydraulic and electronic circuit diagram showing a PTO transmission mechanism of the present invention.

FIG. 2 is a flowchart for controlling by setting the maximum output horsepower during reverse rotation to half of the maximum output horsepower during normal rotation.

FIG. 3 is a drawing showing a configuration in which the rotational speed of an engine E is set lower than a set rotational speed PR of a PTO shaft 1.

FIG. 4 also shows a PTO depending on the number of revolutions of the engine E.
The flowchart drawing of the Example which made lower than the set rotation speed PR of the shaft 1. FIG.

FIG. 5 is a flowchart of control for performing output restriction or input restriction based on a calculation result of an input rotation speed, an output rotation speed, and a hydraulic pressure.

FIG. 6 is a flowchart of control for performing output restriction by a rack position sensor and an output rotation speed.

FIG. 7 shows a hydraulic motor M when torque must be ensured when the output is at or near the limit.
6 is a flowchart of a control for reducing the number of revolutions of the vehicle.

FIG. 8 shows a state in which the work implement is driven via the HST-type transmission,
When turning off the rotation of the PTO shaft 1, set the clutch 2
The flowchart figure of control which performs F.

FIG. 9 is a flowchart of control in which a neutral stop valve 3 for short-circuiting a closed circuit is provided as shown in FIG. 1 instead of providing a clutch 2 between a hydraulic motor M and a PTO shaft 1.

FIG. 10 is a flowchart of control for disconnecting the clutch 2 and the neutral stop valve 3 when the rotation of the engine E is stopped.

FIG. 11 is a drawing showing a state in which a clutch is provided on one or both of the input side and the output side of the HST transmission.

FIG. 12 is a view showing a state in which the reverse rotation valve 8 is interposed in the closed circuit of the HST transmission, and the swash plate setting lever 19 is not operated;
FIG. 3 is a hydraulic circuit diagram that enables switching between forward and backward by switching a reverse rotation valve 8.

FIG. 13 is a flowchart of forward / reverse switching by the reverse rotation valve 8;

FIG. 14 is a diagram showing a PTO in the case of normal / reverse switching by the reverse valve 8;
Drawing of operation lever 23 and detection switches 24 and 25.

FIG. 15 is a flowchart of control for driving the solenoid solC of the reversing valve 8 by pulse driving and changing the duty ratio of the pulse to change the rotation speed of the PTO shaft 1;

FIG. 16 detects the load based on the load set by the engine load setting device and the position of the governor rack, and controls the rotation speed of the PTO shaft 1 by operating the swash plate of the HST transmission with the load. Flowchart drawing.

FIG. 17 is a flowchart for controlling the clutch 2 to be connected before the output shaft 17 of the hydraulic motor M starts rotating when the swash plate is instructed to rotate from neutral to forward rotation or reverse rotation.

FIG. 18 shows a state in which the PTO shaft 1 is stopped or in the vicinity of a stopped state.
FIG. 4 is a flowchart of a control for preventing the pressure of the HST transmission from exceeding the set pressure when the rotational speed is increased to a set rotational speed.

FIG. 19 shows a case where the clutch 2 is disposed between the output shaft 17 and the PTO shaft 1 and the rotation speed of the output shaft 17 is substantially equal to the rotation speed of the PTO shaft 1 when the PTO shaft 1 is rotating. FIG. 4 is a flowchart of a control in which the clutch 2 is connected for the first time when the clutch 2 is turned on.

[Description of Signs] 1 PTO shaft 2 Clutch 3 Neutral stop valve 4 Swash plate operation valve 5 Swash plate operation cylinder 6 Swash plate angle detection sensor 7 Swash plate setting lever sensor 8 Reverse rotation valve 10 Charge pump

Claims (4)

(57) [Claims] 1. An HST type transmission is interposed in a transmission circuit for transmitting power to a PTO shaft 1 of a work vehicle .
The rotation of the PTO shaft can be changed continuously, and the PTO shaft can be rotated forward and backward, so that the maximum output horsepower of the PTO shaft 1 at the time of reverse rotation is smaller than the maximum output horsepower at the time of normal rotation. PTO transmission mechanism. 2. The PTO transmission mechanism according to claim 1,
The input or output speed of the HST transmission;
Based on the calculation result of the hydraulic pressure of the HST transmission, H
A PTO transmission mechanism for limiting output or input of an ST-type transmission. 3. An HST-type transmission, wherein an HST-type transmission is interposed in a transmission circuit for transmitting power to a PTO shaft 1 of a work vehicle so that the rotation of the PTO shaft can be continuously variable. A PTO transmission mechanism, wherein a clutch is interposed on one or both of an input side and an output side, and the clutch is disengaged when the HST type transmission is operated in a neutral state. 4. The PTO transmission mechanism according to claim 1,
When the PTO shaft 1 is stopped or in the vicinity of the stopped state, and is increased to the rotation speed set by the rotation speed setting means, the rotation speed is controlled so that the hydraulic pressure of the HST transmission does not increase beyond the set oil pressure. PTO characterized by
Transmission mechanism.