JPS61285908A - Traction load sensor of tractor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a tractive load sensing device for a tractor, and prevents the chattering phenomenon of a hydraulic control valve that occurs due to the impulsive movement of a sensing bar during draft control. It was designed to do so.

(Prior art) In the traction load sensing device used for large tractors,
For example, as disclosed in Japanese Utility Model Application Publication No. 57-155450, a sensing bar made of an elastic body is inserted laterally into the lower part of the tractor body, and lower links are connected to both ends of the sensing bar. A rocking lever that responds to movement is pivotally supported on the lower end side, and the upper end of this rocking lever is linked to the draft control system of the hydraulic system mounted on the tractor body, thereby controlling the movement of the sensing bar. There is a device that transmits the information to the draft control system via a swing lever.

(Problem to be solved by the invention) In this type of device, the sensing bar is brought into contact with the stop on the rocking lever side, and the movement of the sensing bar is directly transmitted to the rocking lever. When performing draft control during field work, the weight of the work equipment, such as the plow, and the hardness of the soil in the field can cause vibration in the sensing bar, which can cause chattering in the hydraulic control valve. Ta.

That is, when shallowly cultivating a field with hard soil using a plow, the plow vibrates continuously, causing an impactful vibration in the sensing bar via the lower link. When this is transmitted to the swing lever, the swing lever swings with an impact, causing chattering in the hydraulic control valve, causing the plow to repeatedly move up and down unstably, or to move upward, making it impossible to work. I sometimes fell into this.

(Means for Solving the Problems) The present invention aims to solve the above problems, and as a specific means for that purpose, it provides a traction load sensing device with lower links connected to both left and right ends. A sensing bar is installed horizontally on the tractor body, and the movement of this sensing bar is transmitted to the draft control system of the hydraulic system on the upper part of the tractor body via a swing lever that is swingably supported on the lower end side. In a tractor traction load sensing device configured to transmit power, a buffer means is provided between the sensing bar and the swing lever to absorb impact movement of the sensing bar.

(Function) When the load is light, the sensing bar 6 contacts and presses the stopper 37, but the spring 41 does not contract. If the sensing bar 6 has an impact movement, the spring 41 is activated via the stopper 37 and the pin 40.
is compressed and shrinks, so it is not transmitted to the swinging lever 34 side of the sensing bar 6. Therefore, the hydraulic control valve 21 does not chatter.

(Example) Hereinafter, the present invention will be described in detail with reference to the illustrated example.
In the figures and FIG. 2, reference numeral 1 denotes a tractor body, which includes a transmission case 2, etc., and a differential device 3 is built in the mission case 2. Reference numeral 4 denotes a lower link that constitutes a three-point linkage mechanism for attaching a working machine to the rear of the tractor body 1, and there are two pairs on the left and right. It is connected to both ends of the bar 6. The sensing bar 6 is made of an elastic body, and is supported by the transmission case 2 by a support 7 with a clearance.

8 is a hydraulic system for lifting and lowering the working machine, and as shown in FIG. 3, it includes a housing 9, a cylinder 0. It has a piston 11, a piston rod 12, a hydraulic arm 13, a hydraulic arm shaft 14, a lift arm 15, and the like. The cylinder 10 is the housing 9
It is attached inside, and the piston 11 is fitted therein. As shown in FIG. 4, the piston 11 has a wide circumferential groove 16 and a narrow circumferential groove 17 formed on its outer periphery, and the former circumferential groove 16 has a bush 18 and the latter circumferential groove 17 has an O-ring 19, respectively. It is provided.

Bush 1st is formed wide in the axial direction, and the 5th
As shown in the figure, it is C-shaped and has a Teflon layer 2 on its outer circumferential surface.
0 is formed and is adapted to come into sliding contact with the inner circumferential surface of the cylinder 10.

Reference numeral 21 denotes a hydraulic control valve for controlling the hydraulic device 8, which is installed inside the housing 9 and is connected to the position lever 2.
Position control and draft control are possible via the control linkage mechanism 24 according to the settings of the draft lever 23 and the draft lever 23. The control link mechanism 24 includes a position cam 25, a cam rod 23, a spool lever 26, a bushing metal fitting 27,
Position connector 28, swing link 29, position balancer 30, draft link 31, draft arm 3
2. It comprises a draft cam 33 and the like.

Reference numeral 34 denotes a swinging lever arranged vertically in the rear part of the mission case 2, which can swing back and forth on the lower end side via a horizontal pivot 36 on a mounting base 35 attached to the bottom wall of the mission case 2. is supported by.

The swing lever 34 detects the movement of the sensing bar 6 using the draft cam 33.
A buffer means 38 is provided on the lower side with a contact seat 37 facing the sensing bar 6, and a bifurcated portion 39 is provided on the upper end side of the swing lever 34. It is formed. The buffer means 38 is for absorbing the impact movement transmitted from the sensing bar 6 to the swinging lever 34, and the pin 40, which is integrated with the stopper 37, slides on the swinging lever 34 as shown in FIG. It is freely inserted and biased toward the sensing bar 6 by a spring 41. The spring 41 is a spring receiver 42
and the adjustment screw 43, and the adjustment screw 43
By adjusting the forward and backward movement, you can set the spring pressure to any desired value. The spring 41 is set under conditions such that it does not contract during draft control under normal light loads, but there is a gap A between the stopper 37 and the swing lever 34, and it contracts when an impact load is applied. In addition, when working with heavy loads, temporary 3
7 may come into contact with the swing lever 34.

Reference numeral 44 denotes a swinging link that can swing integrally with the draft cam 33, and a roller 45 at the tip is attached to the forked part 3 of the swinging lever 34.
9. 46 is a return spring that biases the swing lever 34 toward the low load side.

In the above configuration, for draft control, the position lever 22 is fully operated in the downward direction (arrow a), and the draft lever 23 is set at an appropriate position.

When plowing is performed by attaching a plow to the three-point linkage mechanism, a traction load is applied to each lower link 4 in the direction of arrow b, so the sensing bar 6 elastically deforms in an arc shape according to the load, At this point, the swing lever 34 is pushed forward as shown by arrow C via the stopper 37 of the buffer means 38. The swing lever 34 swings around the pivot 36 in the direction of the arrow d, and rotates the swing link 44 and the draft cam 33 clockwise around the fulcrum 47, so the draft cam 33 and the draft arm 3
2, the swinging arm 29 rotates clockwise around the fulcrum 48 (
As the spool lever 26 rotates clockwise around the fulcrum via the bushing metal fitting 27, the spool 50 of the hydraulic control valve 21 is pushed in the direction indicated by the arrow f. Accordingly, the hydraulic control valve 21 is switched to the upward direction, and the hydraulic system 8 is operated in the upward direction to lift the plow and reduce the load. Then, when the load decreases, each part from the swing lever 29 to the spool 50 operates in the opposite direction to the above, working in the downward direction. This control is performed according to the attitude of the draft arm 32, that is, the setting of the draft lever 23, since the arm 51 rotates in conjunction with the draft lever 23 and the draft arm 32 is operated via the draft link 31. Needless to say.

When working under a light load, the spring 41 does not contract when the sensing bar 6 contacts and presses the stopper 37 side, and the stopper 37
There is a gap A between the swing lever 34 and the swing lever 34, and the swing lever 34 swings around the pivot 36 via the spring 41. When impact vibrations occur repeatedly in the plow, the sensing bar 6 is elastically deformed and presses the spring 41 via the stopper 37 and the pin 40.
is compressed and shrinks, absorbing the impact. Therefore, the impactful movement of the sensing bar 6 is no longer transmitted to the swing lever 34, thereby preventing the chattering phenomenon from occurring in the hydraulic control valve 21.

Since the piston 11 slides inside the cylinder 10 or uses a wide bush 18, the piston 11 does not fall with respect to the axis of the cylinder 10 even when subjected to side pressure, and the outer periphery of the bush 18 Since the Teflon layer 20 is formed on the surface, the coefficient of sliding friction with the cylinder 10 is reduced, and the occurrence of galling and scratches on the inner peripheral surface of the cylinder 10 can be prevented. Since the Teflon layer 20 absorbs dust, the inner circumferential surface of the cylinder 10 will not be damaged by the dust biting in.

By using the shell 18, there is no restriction on the cylinder diameter.

Note that instead of the Teflon layer 20, a copper alloy-based wear-resistant treatment may be applied.

The buffer means 38 is not limited to the configuration of the embodiment, and may be any mechanism that can cushion and absorb impact.

(Effects of the Invention) According to the present invention, since a buffer means is provided between the sensing bar and the swinging lever to absorb the impact movement of the sensing bar, vibrations generated on the working machine side cause the hydraulic control valve to No chattering phenomenon occurs during operation, and stable draft control is possible even when working with light loads.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is an overall cutaway side view, FIG. 2 is a cutaway rear view of the same, FIG. 3 is a sectional view of the hydraulic system, and FIG. 4 is a partially enlarged view of FIG. 3. 5 is a front view of the bushing, and FIG. 6 is an enlarged view of the main part of FIG. 1. 1--Tractor body, 4--Lower link, 6--Sensing bar, 8-Hydraulic system, 21--Hydraulic control valve, 24-Control link mechanism, 34-Swing lever, 37--Temporary, 3
8-buffer means, 41-spring.

Claims (1)

[Claims] 1. A sensing bar for sensing traction load with lower links connected to both left and right ends is provided horizontally on the tractor body, and the movement of this sensing bar is controlled by a swinging lever that is swingably supported on the lower end side. In the tractor traction load sensing device, which transmits the information to the draft control system of the hydraulic system on the upper part of the tractor body through the sensing bar, a buffer means is provided between the sensing bar and the swing lever to absorb the impact movement of the sensing bar. A tractor traction load sensing device characterized by being provided with.