JP3549300B2 - Agricultural tractor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an agricultural tractor provided with a double-acting cylinder operated by a working fluid such as working oil or working air.
[0002]
[0003]
[Problems to be solved by the invention]
[0004]
An object of the present invention is to provide an agricultural tractor having a double-acting cylinder with a simple structure for operating the double-acting cylinder.
[0005]
[Means for Solving the Problems]
[0006]
[0007]
As shown in claim 1 in accordance with a feature for example FIG. 3 (b), the large-diameter and small-diameter cylinder chamber 21a double Dogata cylinder 11 odor Te by Misao Sakuben, if supplying the hydraulic fluid to 22a, the large diameter piston 23 Is larger than the pressure receiving area of the small-diameter piston 24 and the pressure receiving area of the second piston rod 24b is smaller than the pressure-receiving area of the small-diameter piston 24, while the large-diameter and small-diameter pistons 23 and 24 press each other. The large-diameter and small-diameter pistons 23 and 24 are about to move to the left in the drawing. 24 are retained.
[0008]
In double Dogata cylinder 11 and supplies the hydraulic fluid to the large-diameter cylinder chamber 21a to discharge the hydraulic fluid of the small diameter cylinder chamber 22a by the operation valve, for example, FIG. 3 large diameter as shown in (b) and the small-diameter cylinder portion 21 , 22 with the large-diameter piston 23 abutting against the stepped portion, the small-diameter piston 24 moves to the left in the drawing.
In double Dogata cylinder 11 and supplies the hydraulic fluid to the small-diameter cylinder chamber 22a to discharge the hydraulic fluid of the large-diameter cylinder chamber 21a by the operation valve, for example by a working fluid of the small-diameter cylinder chamber 22a, as shown in FIG. 3 (c) The large-diameter and small-diameter pistons 23 and 24 move integrally to the right in the drawing.
[0009]
According to the features of claim 1 as described above, one and the other, in the double Dogata cylinder you operate in the middle of the 3 position, need to provide one and the other, three operating valve corresponding to each of the intermediate 3 position rather, one and the other a double Dogata cylinder with two operating valves, can be operated in the middle of the 3 position.
Even if the two operation valves of the first aspect are combined into one operation valve, the two operation valves according to the first aspect are compared with a case where three operation valves (functions) are combined into one operation valve. When the (functions) are combined into one operation valve, the structure of the operation valve is simplified.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a transmission system of a four-wheel drive type agricultural tractor, which is an example of a working vehicle, in which the power of an engine 1 is a main clutch 2, a main transmission A, a multi-plate traveling hydraulic clutch 3, The power transmitted to the rear wheels 4 via the forward changeover device C, the first auxiliary transmission device B, the second auxiliary transmission device D, and the rear wheel differential mechanism 4a is transmitted to the transmission shaft 42 immediately before the rear wheel differential mechanism 4a. And transmitted to the front wheels 5 via the front wheel differential mechanism 5a. The power of the engine 1 is transmitted to the PTO shaft 8 via the PTO transmission 6 and the PTO clutch 7.
[0011]
As shown in FIG. 1, the main transmission A is configured as a synchromesh type gear shift type having two sets of shift members 9 and 10, and can shift to four speeds. The first auxiliary transmission B is also of a synchromesh type gear shift type having a set of shift members 30 and can be shifted in two stages. The forward / reverse switching device C also has a shift member 31 similarly. It is configured as a synchromesh type gear shift type. The shift members 9 and 10 of the main transmission A are slid by the first and second hydraulic cylinders 11 and 12, and the shift member 30 of the first auxiliary transmission B is slid by the third hydraulic cylinder 13. The shift member 31 of the forward / reverse switching device C is slid by the swing operation type forward / reverse lever 16.
[0012]
Next, the first and second hydraulic cylinders 11 and 12 will be described.
As shown in FIG. 3A, a large-diameter cylinder portion 21 and a small-diameter cylinder portion 22 are formed, and a large-diameter piston 23 and a small-diameter piston 24 are slidably mounted on the large-diameter and small-diameter cylinder portions 21 and 22, respectively. Have been. A first piston rod 24a is fixed to the end surface of the small-diameter piston 24 opposite to the large-diameter piston 23, and the first piston rod 24a extends to the opposite side to the large-diameter piston 23 and projects from the small-diameter cylinder portion 22. I have. A second piston rod 24b is fixed to an end surface of the small-diameter piston 24 on the side of the large-diameter piston 23, and the second piston rod 24b does not protrude from the large-diameter cylinder portion 21 and slidably penetrates through an opening 23a of the large-diameter piston 23. Have been.
[0013]
As shown in FIGS. 3A and 2, in the small-diameter cylinder portion 22, an electromagnetically operated valve for supplying and discharging hydraulic oil to and from the small-diameter cylinder chamber 22 a on the first piston rod 24 a side partitioned by the small-diameter piston 24. 25 are provided. In the large-diameter cylinder section 21, an electromagnetically-operated valve 26 for supplying and discharging hydraulic oil is provided in a large-diameter cylinder chamber 21a opposite to the small-diameter piston 24 partitioned by the large-diameter piston 23. The solenoid operated valves 25 and 26 are of a three-port type including an input port for hydraulic oil, an output port for hydraulic oil, and a drain port for hydraulic oil, and supply positions for supplying hydraulic oil to the first and second hydraulic cylinders 11 and 12. , And a discharge position for discharging the hydraulic oil. The discharge position is operable and is urged toward the supply position by a spring.
[0014]
With the above structure, when both of the solenoid operated valves 25 and 26 are operated to the supply position, as shown in FIG. 3A, the large and small diameter cylinder chambers 21a and 22a of the first and second hydraulic cylinders 11 and 12 are arranged. Is supplied with hydraulic oil. In this case, the large-diameter and small-diameter pistons 23 are formed by the fact that the pressure-receiving area of the large-diameter piston 23 is larger than the pressure-receiving area of the small-diameter piston 24 and that the pressure-receiving area of the second piston rod 24b is smaller than the pressure-receiving area of the small-diameter piston 24. , 24 are pushing each other, the large-diameter and small-diameter pistons 23, 24 tend to move to the left in the drawing, and the large-diameter piston 23 hits the steps of the large-diameter and small-diameter cylinder portions 21, 22. The large-diameter and small-diameter pistons 23 and 24 are held. The state shown in FIG. 3A is the neutral stop position of the shift members 9 and 10 shown in FIG.
[0015]
When the solenoid operated valve 25 is operated to the oil draining position while the solenoid operated valve 26 is left at the supply position, the hydraulic oil in the small diameter cylinder chamber 22a is discharged as shown in FIG. The second piston rod 24b is pushed leftward on the paper by the hydraulic oil 21a. The state shown in FIG. 3B is the first speed state or the third speed state of the main transmission A in which the shift members 9 and 10 shown in FIG.
[0016]
When the solenoid operated valve 26 is operated to the oil discharge position while the solenoid operated valve 25 is left at the supply position, the hydraulic oil in the large-diameter cylinder chamber 21a is discharged as shown in FIG. The large-diameter and small-diameter pistons 23, 24 are integrally pushed to the right in the drawing by the hydraulic oil 22a. The state shown in FIG. 3C is the second speed state or the fourth speed state of the main transmission A in which the shift members 9 and 10 shown in FIG.
[0017]
Next, the third hydraulic cylinder 13 will be described.
As shown in FIG. 2, a piston 27 is slidably provided inside, and a piston rod 27a fixed to one end face of the piston 27 extends and protrudes from the cylinder. A first chamber 13a on the side of the piston rod 27a partitioned by the piston 27 and a second chamber 13b on the opposite side to the piston rod 27a are formed, and an oil path 28 branched from an oil path 17 described below is formed in the first chamber 13a. To the first chamber 13a so that hydraulic oil is always supplied to the first chamber 13a.
[0018]
As shown in FIG. 2, the second chamber 13b is provided with an electromagnetically operated valve 29 for supplying and discharging hydraulic oil. The solenoid operated valve 29 is a three-port type having an input port for hydraulic oil, an output port for hydraulic oil, and a drain port for hydraulic oil, and is a supply position for supplying hydraulic oil to the second chamber 13b and a discharge position for discharging hydraulic oil. And is urged toward the supply position side by a spring.
[0019]
When the solenoid operated valve 29 is operated to the supply position by the above structure, the operating oil is supplied to the second chamber 13b (the operating oil is already supplied to the first chamber 13a via the oil passage 28). In this case , due to the point that the pressure receiving area of the piston 27 on the side of the first chamber 13a is smaller than the pressure receiving area of the piston 27 on the side of the second chamber 13b, the piston 27 moves to the left as viewed in FIG. The state shown in FIG. 2 is the low-speed position of the first auxiliary transmission B shown in FIG. When the solenoid operated valve 29 is operated to the oil discharge position, the hydraulic oil in the second chamber 13b is discharged, and the hydraulic oil supplied to the first chamber 13a pushes the piston 27 to the right in the drawing. This state is the high-speed position of the first auxiliary transmission B shown in FIG.
[0020]
Next, a hydraulic circuit for the first, second, and third hydraulic cylinders 11, 12, and 13 and the hydraulic clutch 3 will be described.
As shown in FIG. 2, oil passages 17 and 18 are branched in parallel from the pump 15, and an electromagnetic proportional pressure control valve 14 and a pilot-operated operation valve 35 are connected in series to the oil passage 18. The hydraulic clutch 3 is connected to the lower side of the valve 35. The operation valve 35 operates to a supply position 35a where hydraulic oil is supplied to the hydraulic clutch 3 to transmit the hydraulic clutch 3 and an oil discharge position 35b where hydraulic oil is discharged from the hydraulic clutch 3 and the transmission of the hydraulic clutch 3 is cut off. It is a free pilot operation type, and is urged by a spring toward the oil discharge position 35b. The pilot oil passage 20 is branched from the lower side of the throttle unit 19 in the oil passage 17, and the pilot oil passage 20 is connected to the operation valve 35.
[0021]
As shown in FIG. 2, solenoid operated valves 25, 26, 29 are connected to the oil passage 17 on the upstream side from the throttle portion 19. Opening / closing valves 36, 37, 38, 39 urged to the closing side are connected to a lower side of the throttle section 19 in the oil passage 17. In the first piston rod 24a and the piston rod 27a of the first, second, and third hydraulic cylinders 11, 12, and 13, a recess is formed at a position corresponding to a shift position (a first speed position, a second speed position, a low speed position, or the like). In addition, a neutral portion between the shift position and the shift position is formed in a convex shape. An interlocking mechanism 32 that opens and closes the on-off valves 36 to 39 between the shift positions is provided. The same concave and convex neutral portions as described above are also formed on the shift shaft for sliding operation of the shift member 31 in the forward / reverse switching device C, and the opening / closing valve 39 is opened between the forward position and the reverse position. A link mechanism 32 is provided.
[0022]
As shown in FIG. 2, a shift lever 33 is provided which is manually operated by an operator and has operation positions of first to eighth speed positions, and a potentiometer 34 for detecting the operation position of the shift lever 33. signal is being input to the control device 40, the solenoid operated valve 25, 26, 29 is operated by the control unit 40 based on the operation of the shift lever 33. A pressure sensor 41 for detecting a pilot pressure of the pilot oil passage 20 is provided below the throttle unit 19 in the oil passage 17, and a signal from the pressure sensor 41 is input to the control device 40.
[0023]
The state shown in FIG. 2 is a state in which the shift lever 33 is operated to the first speed position, the first hydraulic cylinder 11 is in the first speed position of the main transmission A, the second hydraulic cylinder 12 is in the neutral stop position, and the third hydraulic The cylinder 13 is in the low speed position of the first auxiliary transmission B and the forward / reverse lever 16 is in the forward first speed state in which the forward / reverse switching device C is located at the forward position. As a result, the operation valve 35 is operated to the supply position 35a by the pilot pressure of the pilot oil passage 20, and the transmission operation of the hydraulic clutch 3 is performed.
[0024]
In the first forward speed state shown in FIG. 2, when the shift lever 33 is operated, for example, to the second speed position, the electromagnetically operated valve 25 is operated from the oil discharge position to the supply position, and the electromagnetically operated valve 26 is operated from the supply position to the discharge position. You. Thus, the first hydraulic cylinder 11 operates from the first speed position shown in FIGS. 2 and 3 (b) to the second speed position shown in FIG. 3 (c).
[0025]
During the operation of the first hydraulic cylinder 11, the opening / closing valve 36 is opened by the first piston rod 24a and the linkage mechanism 32 (since the second hydraulic cylinder 12 is in the neutral stop position, the opening / closing valve 37 has already been opened. Has been). Thus, reduces the pilot pressure in the pilot oil passage 20, the operating valve 35 by the urging force of the spring is operated to the oil discharge position 35b from the supply position 35a is hydraulic clutch 3 is transmission interrupted operation.
[0026]
When the sliding operation of the shift member 9 by the first hydraulic cylinder 11 is completed and the main transmission A is shifted to the second speed position, the opening and closing valve 36 is closed by the first piston rod 24a and the linkage mechanism 32. Then, the pilot pressure in the pilot oil passage 20 increases again, and the operation valve 35 is operated from the oil discharge position 35b to the supply position 35a. As described above, when the pressure sensor 41 detects that the pilot pressure has decreased and increased again in the pilot oil passage 20, the electromagnetic proportional pressure control valve 14 is operated by the control device 40 to supply the pilot pressure to the hydraulic clutch 3. The hydraulic oil pressure to be transmitted is gradually increased or rapidly increased based on the operating position of the shift lever 33 or the like, and the hydraulic clutch 3 is transmitted.
[0027]
[Another embodiment of the invention]
In the configuration shown in FIG. 2, two solenoid operated valves 25 and 26 are provided for the first and second hydraulic cylinders 11 and 12, but the large-diameter and small-diameter cylinder chambers 21 a and 22 a shown in FIG. A neutral position where hydraulic oil is supplied to the first cylinder, a first shift position where hydraulic oil is supplied to the large-diameter cylinder chamber 21a and hydraulic oil is discharged from the small-diameter cylinder chamber 22a, and hydraulic oil is supplied to the small-diameter cylinder chamber 22a. One electromagnetically operated valve (not shown) having three second shift positions for discharging the hydraulic oil of 21a is constituted, and one electromagnetically operated valve is provided for each of the first and second hydraulic cylinders 11, 12. May be prepared.
Instead of the electromagnetic operation valves 25, 26, 29 described above, a mechanically operated operation valve may be provided. The present invention is applicable not only to a double-acting cylinder operated by hydraulic oil but also to a double-acting cylinder operated by compressed air.
[0028]
【The invention's effect】
[0029]
According to the features of claim 1, in agricultural tractors equipped with Fukudogata cylinders, one and the other relates to multi Dogata cylinder you operate in the middle of the 3 position, one and the other a double Dogata cylinder with two operating valves , can be operated in the middle of the 3 position, even it summarizes the two operating valve to one operating valve, as it can be summarized operated valve simpler, simplify operation structure of multi Dogata cylinder and Production costs could be reduced.
[0030]
According to the features of claim 1, Te agricultural tractor odor having a Fukudogata cylinder, to hold the double Dogata cylinder at an intermediate position, against the large-diameter piston step of the large-diameter and small-diameter cylinder portion press by being, than double Dogata cylinder is held in an intermediate position, Ri name so it is possible to accurately stop the double Dogata cylinder in an intermediate position, improving the operational performance of the double Dogata cylinder I was able to plan.
[0031]
In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration of the attached drawings by the entry.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a traveling power transmission system. FIG. 2 is a hydraulic circuit diagram for first, second, and third hydraulic cylinders. FIG. 3 is a diagram showing operating states of first and second hydraulic cylinders.
9,10 shift speed change device member 11 12 double Dogata cylinder 21 the large-diameter cylinder portion 21a large-diameter cylinder chamber 22 diameter cylinder portion 22a small-diameter cylinder chamber 23 diameter piston
23a Large-diameter piston opening 24 Small-diameter piston 24a First piston rod 24b Second piston rod
25, 26 Operating valve
36,37-off valve 32 linkage mechanism A speed change device

Claims (3)

A speed change device of the gear shift type (A), a shift member of the speed change device (A) (9), double-acting cylinder for slide operation (10) (11), provided with a (12),
A large-diameter cylinder portion (21) and a small-diameter cylinder portion (22) are formed in the cylinder, and a large-diameter piston (23) and a small-diameter piston (24) are formed in each of the large-diameter and small-diameter cylinder portions (21) and (22). ) Is slidably mounted, and a first piston rod (24a) is fixed to an end surface of the small-diameter piston (24) opposite to the large-diameter piston (23), and the first piston rod (24a) is fixed. The second piston rod (24b) extends to the opposite side of the large-diameter piston (23) and protrudes from the small-diameter cylinder portion (22), and is attached to the end surface of the small-diameter piston (24) on the large-diameter piston (23) side. ) fixing the slide freely through the opening (23a) of said second piston rod (the not to protrude from the large-diameter cylinder portion 24b) (21) large-diameter piston (23) Thereby, before Kifuku Dogata cylinder (11), constitute a (12),
Before SL small diameter cylinder portion in (22), discharging the small diameter piston (24) by said first piston rod (24a) side of the small-diameter cylinder chamber which is partitioned into (22a), the supply position and the working fluid for supplying hydraulic fluid Bei example operations freely operating valve (25) to a discharge position,
Prior Kitai diameter cylinder portion (21), wherein the small-diameter piston (24) and the large-diameter cylinder chamber opposite partitioned by the large diameter piston (23) (21a), the supply position and the operation for supplying the working fluid An operation valve (26) operable at a discharge position for discharging the fluid ,
The working fluid flows from the large-diameter cylinder chamber (21a) through the large-diameter and small-diameter pistons (23), (24) through the opening (23a) of the large-diameter piston (23) and the second piston rod (24b). ), The working fluid being movable between the large-diameter and small-diameter pistons (23) and (24) to the large-diameter cylinder chamber (21a) . The recess corresponding to the operating position, prior Kifuku Dogata cylinder (11), agricultural tractor according to claim 1 which is formed in the first piston rod (24a) of (12). Before Kifuku Dogata cylinder (11), Bei (12) the first piston rod between the recess and the recess of the (24a), on-off valve (36), linkage mechanism for opening operation (37) (32) Ete certain agricultural tractor according to claim 2.

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