JPS5821132B2 - Traveling speed control device for agricultural tractors, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a traveling speed control device for automatically controlling the traveling speed of an agricultural tractor or the like according to the workload of a worker running the machine.

In other words, for example, in an agricultural tractor that is driven while a working machine such as a rotary tiller is indexed and the working machine performs tasks such as plowing, the load applied to the working machine is small or large, and the machine runs smoothly. Unfortunately, it is not possible to perform work under stable conditions without increasing or decreasing the speed, but the present invention is directed to agricultural tractors, etc., which are equipped with a hydraulic clutch type transmission device for changing the traveling power. This is a speed control device that automatically controls the traveling speed of the aircraft according to the work load by skillfully utilizing the existence of the above-mentioned hydraulic clutch type transmission. It is an object of the present invention to provide a novel traveling speed control device that can also change and control the traveling speed of the aircraft independently.

Regarding the illustrated embodiment, the configuration of the traveling speed control device for an agricultural troughter or the like according to the present invention will be explained as follows.
As shown in the figure, an engine 1 is mounted on the front of the aircraft, and the engine 1 drives the left and right rear wheels 2 to rotate the aircraft. The operator who rides the machine rotates the left and right front wheels 5 using a control bundle 4, and the machine is connected to the rear of the machine by a coupling device 6 that can be moved up and down. The PTO shaft 9 of this machine, which is rotationally driven by the engine 1, drives the work machine 7, which is raised and lowered between the illustrated working position and the upper late position by a hydraulic lift device equipped with a lift arm 8. The present invention is carried out in the following manner in an agricultural tractor which performs the following operations by interlocking and connecting to the drive section of the working machine 7 via the flexible transmission shaft 10.

That is, as shown in FIG. 2, the illustrated agricultural tractor is provided with a drive shaft 12 that is interlocked with the engine 1 via a main clutch 11, and there is a connection between the drive shaft 12 and the rear wheels 2. , a hydraulic clutch type transmission 14 disposed between a drive shaft 12 and a transmission shaft 13 parallel to the drive shaft 12;
A hollow conduction shaft 15 on the rear extension portion 12a of No. 2, which is disposed between the hollow conduction shaft 15 that receives input from the conduction shaft 13 and another conduction shaft 16 provided on an extension line of the conduction shaft 13. a gear transmission 17 that is connected to The driving power conduction circuit is completed by interlocking the left and right final gear reducers 20 disposed between the rear wheel axles 23, and the drive shaft extension 20 is connected between the drive shaft 12 and the PTO shaft 9. Intermediate shaft 2 connected to section 12a
1, a transmission shaft 22 connected to the intermediate shaft 21, and a gear-type work machine power transmission 23 disposed between the transmission shaft 22 and the PTO shaft 9.
The work machine power transmission path leading to the construction site has been completed.

Similarly, as shown in FIG. 2, the hydraulic clutch type transmission 14 constituting the main transmission for driving power includes an F1 speed change gear 24, an F2 speed change gear 25, and an F3 speed change gear fixed to the drive shaft 12. The transmission gear 26 and the R transmission gear 27, and the F1 idler gear 28, which is loosely fitted onto the transmission shaft 13 and meshed with the corresponding transmission gear 24-27 on the first drive shaft 12, either directly or via the R intermediate gear 27a. , F2 idler gear 29, F
3 Idle gear 30 and R Idle gear 31, one friction plate is attached to the clutch housing fixedly provided to the transmission shaft 13, and the other friction plate is attached to each of the above-mentioned Idle gears 2 R-31, The Fl hydraulic clutch 3 is configured as a multi-plate type, each of which is supported so that it can slide freely along the clutch axis direction.
2. It has a conventional structure including an F2 hydraulic clutch 33, an F3 hydraulic clutch 34, and an R hydraulic clutch 35, and each idle gear 28-31 is operated by selectively operating each hydraulic clutch 32-35. It is selectively connected to the transmission shaft 13, and can selectively obtain a gear ratio of 1st forward speed F1, 2nd forward speed F2, 3rd forward speed F3, or 1st reverse speed R.

Then, supply and discharge of hydraulic oil to the hydraulic clutches 32 to 35 in this hydraulic clutch type transmission 14 is controlled, and each hydraulic clutch 32, 33, 34 or 35 is selectively operated to adjust each of the above-mentioned speed ratios. As shown in FIG. 3, what is selectively obtained is the oil supply circuit 38 which runs from the oil tank 36 through the hydraulic pump 37 to the hydraulic clutches 32-35, and whose oil pressure is set by the adjustment valve 39. The circuit 38 includes a switching valve 41 as shown, which is operated by a main shift lever 40 in front of the passenger seat 3, that is, a fully hydraulic clutch 32-3.
A neutral position N in which hydraulic oil is drained from 5 toward the tank circuit 42 and all hydraulic clutches 32-35 are inactive, and a neutral position N in which only one hydraulic clutch 32-35 is refueled and the other three hydraulic clutches are From there, hydraulic oil is drained in the direction of the tank circuit 42, and one hydraulic clutch 32, 33 is connected.

This is achieved by providing a switching valve 41 having a forward first speed position F1, a forward second speed position F2, a forward third speed position F3, and a reverse first speed position R, which actuate only 34 or 35.

The above configuration is a usual one, but as shown in FIG. 3, the switching valve 41 has the aforementioned five positions N.

In addition to Fl, F2, F3, and R, there is one additional position AUT
A hydraulic clutch 32 is provided on the secondary side.
In addition to the four ports connected to -35, another port D is provided.

In particular, an auto control valve 43 is provided in the switching valve 4, and the pump port P is connected to the connection port to the next third forward speed hydraulic clutch 34. In addition to the pump port P, there is a tank port T connected to the oil tank 36, and on the secondary side thereof, three connection ports C1, C2, connected to each forward hydraulic clutch 32, 33, 34, C3, and the auto control valve 43 has a function erase position No which connects the pump port P to the connection port C3, and thus connects the hydraulic clutch 34 for third forward speed, and a function erase position No which connects the pump port P to the connection port C1. Auto 1st speed position FI that connects the pump port P to the tank port T and connects the other two connection ports C1 and C3 to the tank port T. 2nd speed position Fll, pump port P is connected to connection port C3, and the other two connection ports C1 and C2 are connected to tank port T.
It is configured with 4 positions, including auto 3rd speed position FI connected to .

The switching valve 41 is in the AUTO position, and the reverse hydraulic clutch 35 is connected to the oil tank 36 via the tank circuit 42.
, 33 are blocked, and the oil supply circuit 3
8 is connected to the pump port P of the auto control valve 43.

The other secondary port D in the switching valve 41 is blocked only in the AUTO position of the switching valve 41, and is connected to the oil tank 36 via the tank circuit 42 in other positions N, F1, F2, F3, and R. It is assumed that it will be connected to

As above, auto control valve 43
The switching valve 41 is moved to the positions N, F1, F2, F3 by operating the lever 40 at the function erase position No.

When selectively switching to R, the shift state of the hydraulic clutch type transmission 14 can be manually changed as in the conventional case, and when the switching valve 41 is to be shifted to the AUTO position, the auto control valve 43 can be switched manually. Auto 1
In the speed position FI, the hydraulic clutch 32 for forward 1st speed is selectively activated, in the auto 2nd speed position FII, the hydraulic clutch 33 for forward 2nd speed, and furthermore, in the auto 3rd speed position Fn, the hydraulic clutch 34 for forward 3rd speed is selectively activated. The following mechanism is provided to automatically change the position of the auto control valve 43 with the switching valve 41 in the AUTO position.

That is, the auto control valve 43 is configured to include a spool (not shown) similar to that in a normal switching valve, and the spool is moved forward or backward according to a heading by operating the bundle 44, as shown in FIG. The spool is slid and energized in the direction of the function erasure position No. by a compression spring 4γ whose end is received by a movable spring receiver 46 which rests on the adjusting screw 45. It is designed so that the spooler is displaced in a seismic manner by being pushed by this hydraulic pressure.

That is, as also shown in FIG.
A control circuit 50 is provided which is supplied with pressure oil from the oil tank 36 and sets the oil pressure by the pressure regulating valve 49.
It is connected to the port D of No. 1, and is also connected to a pressure oil chamber (not shown) at the tip of the spool of the auto control valve 43 via a connection circuit including a throttle 51 and an accumulator 52.

Therefore, the positions of the switching valve 41 are N, F1, F2,
At F3 and R, since the port D is connected to the oil tank 36 at these positions as described above, oil pressure is not established in the control circuit 50, and the auto control valve 43
is the function erase position N due to the pressing force of the compression spring 47.

However, in the AUTO position of the switching valve 41, where the port D is blocked and hydraulic pressure is established in the control circuit 50, the set hydraulic pressure of the pressure regulating valve 49 is controlled to maintain the hydraulic pressure of the control circuit 50. Change
The following mechanism is provided to control the position of the auto control valve 43.

That is, as shown in FIG. 4, the oil pressure of the pump port 54 acting on the rear oil chamber 53 resists the spring force of the pressure setting compression spring 55; In the pressure regulating valve 49, which is equipped with a valve body 57 that communicates the pump port 54 with the tank port 56 and performs a relief operation, the pressure setting compression spring 55 is a movable spring that can freely slide forward and backward within the valve case 58. The tip of the receiver is received by 59, and the above compression spring 5
5 and another compression spring 60 provided inside the valve case 58, the movable spring support 59 is supported to move forward and backward, and is supported with its tip facing inside the valve case 58. A certain advancing/retracting rod 61 is brought into contact with it.

A hollow shaft 62 is provided on the advancing/retracting rod 61 so as to be freely rotatable, and a gear 63 fixed to the hollow shaft 62 is attached to the P.
Meshing with the gear 64 fixed to the TO shaft 9, PTOTeO2
The hollow shaft 62 is designed to rotate as the shaft rotates.

Further, a bracket 65 protruding from the front surface of a flange 62 a formed at the tip of the hollow shaft 62 is rotatably supported around a pin 66 to provide a plurality of curved arms 67 . A weight 68 is fixed to one end, and the other end of each curved arm 67 is placed on the back side of a large diameter flange 61a formed in the middle of the retractable rod 61, and as the hollow shaft 62 rotates, the weight 68 is attached. When the weight 68 is displaced in the outer circumferential direction by the acting centrifugal force and the curved arm 67 is rotated in the direction of arrow S, the collar portion 61a is pushed by the curved arm 67 so that the advancing/retracting rod 61 is displaced forward. , it is a plan.

As described above, the advancing/retracting rod 61, which is urged to move in the backward direction by the compression springs 55, 60 via the movable spring receiver 59, is affected by the centrifugal force acting on the weight 68 in proportion to the PTOTeO2 rotation speed and the above-mentioned centrifugal force. The force of the springs 55 and 60 is balanced, and the pressure setting compression spring 55 takes the degree of compression according to the position of the movable spring receiver 59 corresponding to the position of the advancing/retracting rod 61, so that the PTOTeO2 rotation number is The higher the pressure is, the higher the set oil pressure of the pressure regulating valve 49 is, and conversely, the higher the PTOTeO2
The smaller the rotation number, the lower the set oil pressure.

Therefore, the position of the switching valve 41 and the hydraulic pressure established in the control circuit 50 in AUTO are so low that the load on the working machine 7 increases and the number of PTOTeO2 rotations decreases, and conversely, the load on the work machine 7 decreases and the number of PTOTeO2 rotations decreases. The control circuit 5 becomes higher as the value of
Due to the balance between the zero oil pressure and the compression spring 47 attached to the valve 43, the auto control valve 43 or its spool moves to the auto 1st speed position FI, which is the rightmost position in the diagram, in a high range exceeding the value of the work machine 7 load. In the intermediate range of the work machine load, the auto control valve 43 or its spool assumes the intermediate auto 2nd speed position Fil, and in the low range of the work machine 7 load, the auto control valve 43
Or the spool is at auto 3rd gear position FI on the left side of the diagram.
The spring constants of the compression spring 55 of the pressure regulating valve 49 and the compression spring 47 of the auto control valve 43 are set so as to take the following equation.

In addition, in the illustrated case, as shown in FIG.
9 is provided in this tank circuit 69, and an unload valve 70 as shown in the figure is provided, that is, a non-operating position I that blocks the tank circuit 69 and a control circuit 5 that unblocks the tank circuit 69.
Insert the unload valve 70 with the unload operating position ■ to unload the hydraulic pressure of 0, and press the compression spring 71.
The lift arm 8 is connected to the unload valve γ0, which is normally in the inoperative position (2) when energized by the operator. The actuating arm 72 and the roller 72a at its tip are connected to each other so as to take the same action.

Therefore, when the working machine 7 is lifted to the upper standby position, the auto control valve 43 is automatically brought to the function erase position No by hydraulic unloading of the control circuit 50.

Note that the gear transmission 17 arranged in the running power transmission path connects the gear 7 from the transmission shaft 13, as shown in FIG.
The hollow power transmission shaft 15 is inputted by the meshing of 3 and 74.
A plurality of speed change gears 76, 76, 77 fixed thereon and another speed change gear 79 on the drive shaft extension 12a, which is inputted from the hollow power transmission shaft 15 via the gear reduction mechanism 78, and the transmission shaft 16 are splined. It is configured to include a plurality of fitted shift gears 80.81.82 and a dog clutch 88 interposed between the transmission shaft 13.16. Due to the selective sliding displacement of gears 79.80, 1st speed (very low speed), 2nd speed (very low speed) when meshing between gears 75 and 80, 3rd speed when meshing between gears 76.81, and 77.82. A gear ratio of 4th speed can be obtained by meshing between the shafts 13 and 16, and a gear ratio of 5th speed can be obtained by directly connecting the shafts 13 and 16 through the operation of the dog clutch 83.

Further, the PTO transmission 23 has a plurality of speed change gears 8 fixed on the transmission shaft 22, as similarly shown in FIG.
4, 85, 86, 87, a plurality of shift gears 88, 89, 90 fitted with a PTO TeO2 line, and a PTO
An idler gear 91 on the shaft 9 and meshed with the speed change gear 84 on the transmission shaft 22 and the shift gear 8
8 and a dog clutch 92 interposed between the shift gear 88 and the shift gear 88 on the PTO shaft 9.
-90 selective sliding displacements allow first gear with actuation of dog clutch 92, second gear with mesh between gears 85 and 88, gear 8
It is said that a gear ratio of 3rd speed can be obtained by meshing between gears 6.89 and 4th speed by meshing between gears 87 and 90.

In FIG. 2, reference numeral 93 denotes left and right brakes for the left and right rear wheels 2, which are arranged at the ends of the differential output shaft 18a.

Since the traveling speed control device shown in FIGS. 1-4 is configured as described above, when cultivating in the field, the working machine 7 has a gear ratio controlled by the gear transmission 17 which is the traveling power sub-transmission device. If the gear ratio of the PTO transmission 23 for power transmission is set appropriately according to the field conditions, etc., and the changeover valve 41 is set to the AUTO position and the work is carried out, the changeover valve 41 adjusts the load acting on the work implement 7. Automatically depending on the size, when the load is high, the auto control valve 43 takes the auto 1st gear position FI and the forward 1st gear hydraulic clutch 32 is operated to make the aircraft travel at the forward 1st gear F1 speed.
In addition, at an intermediate load, the auto control valve 43 takes the auto 2nd speed position Fil, and the oil king clutch 33 for forward 2nd speed is activated.
is activated, causing the aircraft to travel at forward 2nd speed F2, and at low loads, auto control valve 4 is activated.
3 assumes the auto 3rd gear position FM, the hydraulic clutch 34 for the 3rd forward gear is activated, and the machine is made to run at the speed of the 3rd forward gear F3. Since the vehicle speed is automatically controlled according to the vehicle speed, stable and constant plowing work can be carried out at all times.

When the model of the working machine 7 towed by the illustrated agricultural tractor is changed, or when the field conditions change drastically, the compression spring 47 of the auto control valve 43
The spring force can be changed and adjusted by operating the bundle 44, and the relationship between the work machine I load and the position of the auto control valve 43 can be adjusted as appropriate.

From this state, the switching valve 41 is moved to other positions N, F1°F.
2. F3. When shifting to R, the auto control valve 43 is automatically displaced to the function deletion position No. by hydraulic unloading of the control circuit 50 via port D of the switching valve 41, and the switching valve 41 is moved to the normal position. The hydraulic clutch type transmission 14 can be manually operated to change gears, and even when the work implement 7 is lifted to the standby position, it can be automatically changed by hydraulic unloading of the control circuit 50 by the unloading valve flow operation. Control! Since the /valve 43 is automatically displaced to the function deletion position No, the manual speed change operation of the hydraulic clutch type transmission 14 can be performed in the same way.

Next, the fifth and sixth embodiments shown in the drawings will be explained. In this embodiment, the manually operated switching valve 41 has the usual five positions N, F1, . F2. F3. Other positions of R AUTO
In this position AUTO, the pump port of the switching valve 41 is connected to the secondary side connecting port to the forward first speed hydraulic clutch 32, and the secondary side connecting port to the reverse hydraulic clutch 35. is connected to the tank port, and the connection port to the second forward speed hydraulic clutch 33 and the connection port to the third forward speed hydraulic clutch 34 on the secondary side are blocked.

And auto control valve 1 in this embodiment
00 is configured such that its pump port P is connected to the connection port of the switching valve 41 to the hydraulic clutch 32 for the first forward speed, and the pump port P is connected to the primary side of the hydraulic clutch 32 for the first forward speed.
In addition, a tank port T is provided to be connected to the oil tank 36, and connection ports C1, C2, and C3 are provided on the secondary side to be connected to the forward hydraulic clutches 32, 33, and 34, respectively. , this auto control valve 100 has a first speed position FT that connects pump port 1-P to connection port C1 and connects the other two connection ports C2 and C3 to tank port T, and a first speed position FT that connects pump port 1-P to connection port C1, and connects pump port P to connection port C2. and the other two connection ports C1
, C3 to the tank port T;
It is configured to have three positions: a third speed position Fl that connects the pump port 1-P to the connection port C3 and connects the other two connection ports C1 and C2 to the tank port T.

As described above, the position FI of the auto control valve 100 is a position that serves as both the function erase position and the auto 1st gear position, but it is moved toward the 1st gear position Fl by the same compression spring 47 as described above. The auto control valve 100 equipped with the spool 101 being energized is configured as an electromagnetic valve as follows.

That is, as shown in FIG. 6, two electromagnetic solenoids 103 are installed on the end face of the valve case 102 of the valve 100.
, 104, the plunger 1 moves into the valve case 102 by excitation of the solenoids 103, 104.
03a.

104a are installed, and when the plunger 103a of the electromagnetic thread 103 moves as shown in the figure, the spool 101 moves to the 1st speed position F.
When the plunger 104a of the electromagnetic solenoid 104 moves further as shown in the figure, the spool 101 moves from the second speed position Fn to the third speed position FW. compression spring 4
The auto control valve 100 is configured to be displaced against the force of the compression spring 47 when both the electromagnetic solenoids 103 and 104 are demagnetized.
As a result of this action, the spool 101 is held at the first speed position FI.

The following electric control circuit is provided to selectively excite the electromagnetic solenoid 103, 104.

That is, as shown in FIG.
A tachometer generator 107 having a gear 106 meshed with PTOTe is provided.
Two speed switches 108 and 109 are connected to the tachometer generator 107, which generates an output voltage proportional to the O2 rotation speed, so that the output voltage of the tachometer fully electric 10γ is reduced to the set switching voltage. Then, both speed switches 108 and 109 are turned on, respectively.
The set voltage is changed using the set voltage change levers 108a and 109a.

Although the speed switch 1 is configured to be adjustable, both speed switches 1
One of the switching voltages 108 and 109 is set to a high switching voltage, and the other 109 is set to a lower switching voltage.

And one speed switch. 108 is connected to one electromagnetic solenoid 103, and the other speed switch 109 is connected to the other electromagnetic solenoid 104 via a batch IJ-B that constitutes a power source.

As described above, in the rotation speed range equal to or higher than PTOTeO2, both speed switches 108 and 109 are kept off, both electromagnetic solenoids 103 and 104 are demagnetized, and then the work equipment 7 load is With the increase of PTOTe
When the O2 rotation rate drops below a certain amount, the speed switch 10
8 is turned on and the electromagnetic solenoid 103 is energized,
When the plunger 103a protrudes and the number of rotations of the PTO shaft 9 falls below a certain amount due to an increase in the load on the work equipment 7, the speed switch 109 is also turned on, the electromagnetic solenoid 104 is energized, and the plunger 104a will also protrude.

Therefore, by appropriately setting the switching voltages of the speed switches 108 and 109, even in the case of this embodiment, the changeover valve 41 can be placed in the AUTO position during tilling work, and the magnitude of the load on the work implement 7 can be adjusted. According,
Auto control valve 100 in the range of the load
100 to the 1st gear position FI, auto control valve in the middle range of the load; 100 to the 2nd gear position F■, and the auto control valve 100 to the 3rd gear position F in the low load range.
By automatically positioning them at 1 and 1, the vehicle traveling speed corresponding to the load of the working machine 7 can be automatically obtained, and stable and constant plowing work can be carried out at all times.

; position N, F1 of the switching valve 41 which is still manually operated;

Similarly to the previous embodiment, it is possible to manually change the gear ratio by the hydraulic clutch type transmission 14 in switching between F2 t F3 t R, as in the usual case. If it is attempted to automatically erase the function of the auto control valve 100 by lifting the work machine 7 to the standby position as in the case of the previous embodiment, the lift arm 8 will move in conjunction with the upward rotation of the work machine 7. The connection circuit between the tachometer generator 107 and the speed switch 108, 109 or the speed switch 108
．． 109 and the electromagnetic solenoids 103 and 104 by being inserted into the connection circuit.

Furthermore, in the case of this embodiment, when there is a change in the model of the work machine 7 or a major change in field conditions, the relationship between the work machine γ load and the position of the auto control valve 100 can be adjusted by switching to the speed switches 108 and 109. The set switching can be changed and adjusted by operating the voltage levers 108a and 109a.

As a modification of the embodiment shown in FIGS. 5 and 6, the tachometer generator 10γ is omitted, and the speed switches 108 and 109 are turned on at a constant rotation speed of PTOTeO2 and another constant rotation speed, respectively. The same effect as described above can also be achieved by changing to a governor switch.

Further, in the above two embodiments, the auto control valves 43, 100 are configured as hydraulic pilot or electromagnetic pilot type valves, and the auto control valves 43 or 100 are configured as load detection means for detecting the load of the working machine 7. The two are connected by hydraulic or electrical connection means, for example, by aligning the reciprocating rod 61 shown in FIG. 4 with the spool end of the auto control valve 43 shown in FIG. It is also possible to configure the auto control valve 43 to be automatically displaced by the work machine load detection means via a mechanical connection means.

Furthermore, in the above embodiment, the detection of the work machine load is performed using the PTOT.
For example, as schematically shown in FIG. 7, the top ring 6 in the coupling device 6
The bracket 12 is rotatable around the fulcrum 120a.
At the same time, the top ring 6a is pivoted to the bracket 120 which is rotated in the opposite direction of the arrow A by the tension spring 121, and the top ring 6a The bracket 120, which is rotatably displaced in the direction indicated by the arrow, is attached to the spool of an auto control valve 100' similar to the auto control valve 100, and each link piece is rotated in the direction indicated by the arrow as the bracket 120 is rotated in the direction indicated by the arrow. a link device 1 that displaces the spool in the pushing direction by displacing the spool in the pushing direction;
22, the valve 100' position can be determined by the balance between the load, the force of the spring 121, and the force of the valve spring 47', that is, the load acting on the working machine 7 can be directly detected. It is possible to do something like this.

The embodiment shown in FIG. 7 is an auto control valve 10.
0' and the load detection means 120°121.
This is also an example of connection using a mechanical connection means such as 22.

As is clear from the above description, the running speed control device for an agricultural tractor or the like of the present invention is applicable to an agricultural tractor or the like that is equipped with a hydraulic clutch type transmission 14 for changing the driving power. In the hydraulic oil supply/discharge circuit for the multiple hydraulic clutches 32, 33, 34, 35 in ε, the multiple hydraulic clutches 32, 33, 34,
In addition to the manually operated switching valve 41 that switches and controls the supply and discharge of hydraulic oil to and from the hydraulic oil transmission device 14
Multiple hydraulic clutches for forward speed change in S32.33
．． An auto control valve 43 or 100 or 100' is provided to switch and control the supply and discharge of hydraulic oil to and from the valve 34, and the switching valve 41 is provided with an auto control position AUTO that allows the auto control valve to control the supply and discharge of hydraulic oil. In addition, the switching valve 41 and the plurality of hydraulic clutches 32, 33, for forward speed change.
The oil supply/discharge circuit connecting one of the hydraulic clutches 34 (as shown in FIG. 3) or 32 (as shown in FIG. 'The above-mentioned switching valve 41 and auto control valve 43 or 10
The oil supply/discharge circuit portion located between 0 and 100' is connected to the auto control valve 43, 100, or
An auto control valve 43 or 100 or 10 is also installed in the oil supply circuit for guiding hydraulic oil to the primary side of 00'.
0' and the above-mentioned one hydraulic clutch 34 or 32, when the switching valve 41 is in the auto control position AUTO, the one hydraulic clutch 3
Load detection means 49, 61, 62, 68 or 107° 108.1 configured in the oil supply/drainage circuit for supplying and discharging hydraulic oil to and from 4 or 32, respectively, and detecting the work machine load.
09 or 120, 121 is provided to connect the above-described switching valve 4 between the above-mentioned auto control valve and the load detection means.
In the first auto control position AUTO, the auto control valve is connected so as to be displaced toward the low speed shift position as the work machine load increases, and has the following advantages.

That is, since the traveling speed control device of the present invention is configured as described above, when the switching valve 41 is set to the auto control position AUTO to proceed with work such as tilling, the tiller etc. The running speed of the machine is dynamically changed and controlled to keep the work constant according to the magnitude of the load on the work equipment, and work can be automatically performed under stable and constant conditions. However, it is possible to manually change and control the machine running speed by manually operating the switching valve 41 to a position other than the auto control position AUTO. When carrying out work that yields consistent work results, rather than having to frequently automatically change vehicle speed depending on field conditions, the operator can change the machine's running speed as appropriate depending on the work conditions while performing the work. When traveling on the road, the machine's running speed can be changed freely regardless of the workload, and it is safe because there is no accidental automatic vehicle speed change, and the machine's running speed can be controlled. The switching means for switching between automatic control and manual control is provided with a simple structure in which the switching valve 41 for manual control is provided with the auto control position as described above.

Further, the traveling speed control device of the present invention has an oil supply/drainage circuit connected from the switching valve 41 to one hydraulic clutch 34 or 32 for forward speed change, and connects the auto control valve 43 to the hydraulic clutch 34 or 32.
or 100 or 100', and when the switching valve 41 is in the auto control position AUTO, the oil supply and drainage circuit located between the switching valve and the auto control valve is operated on the primary side of the auto control valve. Oil is supplied to the one hydraulic clutch 34 or 3 through the oil supply circuit portion located between the auto control valve and the above-mentioned one hydraulic clutch 34 or 32.
2, the structure is particularly simplified.

That is, by configuring as described above, the oil supply/drainage circuit between the manually operated switching valve 41 and one hydraulic clutch 34 or 32 is connected to the hydraulic clutches 32, 33, 32, 32, and 32 for forward speed change during automatic vehicle speed control. The number of oil passages is reduced by serving both as an oil supply circuit for supplying hydraulic oil in 34 directions and as an oil supply and discharge circuit for supplying and discharging hydraulic oil to one hydraulic clutch 34 or 32. Of course, the switching valve 4
1 and forward speed change.

In a structure in which the multiple hydraulic clutches 32, 33, and 34 for high-speed operation are all directly connected through an oil supply/drainage circuit, in addition to the number of clutch ports corresponding to the secondary side of the switching valve 41, oil is supplied toward the auto control valve. However, according to the present invention, the structure of the switching valve 41 becomes significantly complicated by adding more ports to the switching valve 41, which originally has a large number of ports. clutch 34
Alternatively, the clutch port for 32 and the oil supply port toward the auto control valve are common, and the switching valve 41 is provided with the same number of ports as the switching valves provided when automatic vehicle speed control is not performed. Therefore, the structure of the device of the present invention is particularly simplified, without complicating the valve structure.

[Brief explanation of the drawing]

Fig. 1 is a side view of an agricultural tractor equipped with an embodiment of the present invention, Fig. 2 is a mechanical diagram of the power transmission mechanism of the agricultural tractor, and Fig. 3 is a circuit diagram of the hydraulic circuit of the same embodiment. Figure 4 is a longitudinal sectional view of only the main parts of the same embodiment, Figure 5 is a circuit diagram showing the hydraulic circuit and electric circuit of another embodiment, and Figure 6 is the main part of the same embodiment. 7th vertical cross-sectional partial view of the member of
The figure is a schematic diagram showing still another embodiment. DESCRIPTION OF SYMBOLS 1... Engine, 7... Work equipment, 9... PTO shaft, 14... Hydraulic clutch type transmission, 32, 33, 3
4゜35...Hydraulic clutch, 41...Switching valve, 43
...Auto control valve j, 47...Compression spring, 48...Hydraulic pump, 49...Pressure regulating valve, 50...
...Control circuit, 55...Compression spring for pressure setting, 59...Movable spring holder, 61...Advancing/retracting rod, 62...
・Hollow shaft, 67... Curved arm, 68... Weight, 1
00...Auto control valve, 101...Spool, 103,104...Electromagnetic solenoid, 103
a, 104a... Plunger, 107... Tachometer generator, 108, 109... Speed switch, 120
... Bracket, 120a... Fulcrum, 121...
Tension spring, 122...link device.

Claims (1)

[Claims] 1. In agricultural tractors, etc., which are equipped with a hydraulic clutch type transmission for changing traveling power, the hydraulic oil is supplied and discharged to and from the plurality of hydraulic clutches in the hydraulic oil supply and discharge circuit for the plurality of hydraulic clutches in the hydraulic clutch type transmission. In addition to a manually operated switching valve for switching and controlling the switching, an auto control valve is provided for switching and controlling the supply and discharge of hydraulic oil to the plurality of hydraulic clutches for forward speed shifting in the hydraulic clutch type transmission device, and the switching valve is provided with: An auto control position is provided to allow the auto control valve to control the supply and discharge of hydraulic oil, and an oil supply connecting the switching valve to one of the plurality of hydraulic clutches for forward speed change. A drainage circuit is provided to pass through the auto control valve, and the oil supply/drain circuit portion located between the switching valve and the auto control valve is connected to the primary side of the auto control valve at the auto control position of the switching valve. In the oil supply circuit for introducing hydraulic oil, there is also a history control valve, which is connected to the one hydraulic clutch at the auto control position of the switching valve of the oil supply/discharge circuit part located between the one hydraulic clutch. On the other hand, the oil supply and discharge circuits for supplying and discharging hydraulic oil are configured respectively, and a load detection means for detecting the load of the work machine is provided, and the switching valve is At the auto control position, the greater the work machine load, the more the auto control valve is displaced toward the low speed shift position J, j
-L, a traveling speed control device characterized by being connected in a manner that allows the user to connect the vehicle to the vehicle.