JPH0429658A - Tension clutch structure - Google Patents

Abstract

PURPOSE:To surely realize a clutch-off condition by mounting a single spring which generates energizing force in a manner wherein the spring is extended or compressed by movement along a center line of a flection point of flection links so as to return the flection point on the center line. CONSTITUTION:A clutch-off condition is realized by moving a flection point Z of flection links 16a, 16b on a enter line X which provides connection between both rotational centers of drive and driven pulleys 10, 11. Power is transmitted even in the clutch-off condition by displacing the flection point Z to either right or left from the center line X in the clutch-off condition. When a spring 22 is mounted to the flection point Z of the flection links 16a, 16b, energizing force is generated in the spring 22 by displacing the flection point Z to a clutch- off side. The flection point Z, even when it tends to generate the right/left displacement from the center line X, is return-operated onto the center line X by the energizing force of the spring 22. The spring 22 tries to return the flection point Z onto the center line X whichever side the flection point Z is displaced from the center line X, so that only the signal spring 22 is required.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tension clutch structure for a belt-type transmission mechanism used for power transmission in work vehicles such as walk-behind lawn mowers and agricultural tractors.

(Prior Art) Some walk-behind lawn mowers are equipped with a heald type transmission mechanism and a tension clutch structure as shown in Figures 4 and 5 for driving power.In other words, the power of the engine (not shown) is Drive pulley (10) that can be driven forward and backward by
A transmission belt (12) is wound around the driven pulley (11) on the side of the rear running wheel (2), and the left and right heald portions (1, 2a) of this transmission heald (12).
, (12b), a pair of first tension pulley (13a) and second tension pulley (13
b) Place. The first and second tension pulleys (13a) and (13b) are connected to a first tension arm (14a) and a second tension arm (14b) that are independently swingable around the horizontal axis (P,). attached, and first and second tension pulleys (13a);
A tension spring (15) is installed across (13b).

The state shown by the solid line in Fig. 4 is the state in which the drive pulley (10) is stopped, but as shown in Fig. 5, when the drive pulley (10) rotates counterclockwise in the paper, the heald portion on the right side of the paper (12a) becomes stretched due to tension. As a result, the first tension pulley (13a)
is pushed out to the right in the plane of the paper, and along with this, the second tension pulley (13b) is also pulled in to the right in the plane of the paper. Therefore, the second tension pulley (13
b), the belt part (12b) on the left side of the paper is pushed in, and the transmission heel 1-(1
2) The overall tension is maintained and power is transmitted to the driven pulley (11).

Next, let's talk about the tension clutch structure that cuts off the power in this belt type transmission mechanism.

As shown in Figure 4, the first and second tension arms (1
At the tips of 4a) and (14b), there is a bending link (16a).
) (16b) is attached, and the refractive link (1
The tips of 6a) and (16b) are connected with pins.

Then, the connection point (this position is the bending link (16a)
, (16b) becomes the inflection point (Z)) at the lot (
23) are connected by pins.

With the above structure, when the lot (23) is pulled downward in the drawing, the bending point (Z) moves downward in the drawing, and the bending links (16a) and (16b) move the first and second tension pulleys (13a). , (13b) will be pushed to the left and right. This allows the power transmission belt (
12) is weakened and a clutch disengaged state is obtained (one-point chain failure in Fig. 4: the state shown).

[Problem to be solved by the invention]

In the conventional structure described above, the first and second tension arms (1
4a), (14b), and refractive link (16a)
(16b) are each supported by a pin connection structure so that they can freely swing, so that the first and second tension pulleys (13a)
Even if the clutch is disengaged by pushing the (13b) apart to the left and right, the first and second tear'/y7 pulleys (1
3a) and (13b) are unified and swing left and right.

In such a state, the tension of the transmission belt (12) is increased again by the first and second tensile pulleys (13a) and (13b) that have swung left and right, and the power of the drive pulley (10) is transferred to the driven pulley. (11).

The present invention provides a tension clutch structure as shown in FIG. 4, which can reliably produce a clutch disengaged state.
The purpose is to have a simple configuration with fewer parts.

(Means for Solving the Problems) A feature of the present invention is that in the tension clutch structure as described above, the bending link is tensioned or compressed by movement of the bending point along the center line, and the bending point is moved along the center line. (
A single spring that urges the spring to return upward (a straight line connecting the rotation centers of the driving and driven pulleys) is attached to the bending point, and its functions and effects are as follows.

[Function] In the case of the above structure, the bending points (Z) of the bending links (16a) and (16b) as shown in FIG.
) moves on the center line (X) connecting the rotation centers of the driving and driven pulleys (10) and (II), thereby creating a clutch disengaged state. Then, when the clutch is disengaged, the bending point (Z) is displaced from the center line (X) to either the right or the left, so that power is transmitted even when the clutch is disengaged.

Therefore, when the springs (22) of the present invention are attached to the bending points (Z) of the bending links (16a) and (16b), the springs (22) are displaced by the bending points (Z) toward the clutch release side. A biasing force is generated. Even if the refraction point (Z) tries to displace from the center line (X) to the left or right, there will be a splash (
It is operated to return to the center line (X) by the urging force of 22).

Then, no matter which direction the refraction point (Z) is displaced from the center line (X), the blade (22) tries to return the refraction point (Z) to the center line (X), so a single blade ( 22) is sufficient.

〔Effect of the invention〕

As described above, in order to maintain the bending point of the bending link on the center line during clutch disengagement, in other words,
It is now possible to operate the first and second tension pulleys at equal intervals from the center line, and it is now possible to reliably make the clutch disengaged state appear, and when the clutch is disengaged, power is transmitted and the driven side is There was no more movement.

Also, since only a single spring is required, the structure is simple.
The increase in production costs is also small.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a case where an embodiment of the present invention is applied to a walk-behind lawnmower, which is one type of work vehicle, will be described based on the drawings.

As shown in Figure 3, a 3Mi rotary cutting blade (4) is installed at the bottom of the fuselage (3) supported by the front wheels (1) and rear wheels (2).
A mower (5) equipped with
7) A self-propelled walk-behind lawnmower is constructed with a control knob (8) at the rear of the machine.

Next, the transmission structure of the traveling system of this walk-behind lawn mower will be explained. As shown in FIG. 3, the power of the engine (6) is transmitted to the rear traveling transmission case (9) via a heald transmission mechanism (not shown). This transmission case (9) is equipped with a gear transmission mechanism (not shown) capable of switching between forward and reverse rotations, and as shown in Figure 1, the power for forward or reverse rotation is transferred to the left and right rear wheels (2 ) are provided on the left and right sides of the transmission case (9), respectively. Also, this drive boo IJ
- (10) is located obliquely above and behind the driven pulley (11) on the rear wheel (2) side.

As shown in Figure 1, the driven pulley (11) on the rear wheel (2) side
) and the drive pulley (10).
) or wound. In the transmission belt (12), a first tension pulley (13a) is arranged outside the winding path of one belt portion (12a) between the drive pulley (10) and the driven pulley (11), and (12b) The second tension pulley (
13b) are arranged.

These first and second tension boots U (13aL(1
3b) is attached to the tips of a first tension arm (14a) and a second tension arm (14b) that are independently swingable around the horizontal axis (Pl) of the left and right side plates (17), A tension spring (1) extends between the first tension pulley (13a) and the second tension pulley (13b).
5) has been constructed.

First and second tension arms (14a), (14
At the tip of b), there is a swingable bending link (16a),
(16b) is attached, and the refractive link (16b) is attached.
The tips of aL (16b) are connected with pins. Then, the operating arm (
18) is swingably supported, and the bending link (1
A linking member (20) is installed with a pin connection structure between the tips of 6a) and (16b) and the tip of the operating arm (1 arm). A spring (22) is installed across the tip of the linking member (20).In this case, the spring (22) is installed over the center line (X) connecting the rotation centers of the drive boob IJ-(10) and the driven pulley (11). A fixing part (23) is located slightly above.

The structures such as the transmission belt (12) and the first and second tension pulleys (13a) and (13b) as described above are provided on each of the left and right rear wheels (2), and are attached to the steering wheel (8). Clutch levers (19a) provided on the left and right
, (19b) and the left and right operating arms (18) are connected via wires (21).

The state shown in Fig. 1 is the clutch lever (19a) (19b).
), and the wing (22) is at its natural length. As a result, the first and second tension arms (14a) and (14b) are connected to the bending links (
16a) and (16b) and can freely swing around the horizontal axis (Pl), and the drive pulley (10)
When rotated forward or reverse, the first and second tension pulleys (13a) and (13b) move in one direction, as shown in FIG. 5, and power is transmitted to the driven pulley (11).

When the clutch levers (19a) and (19b) are gripped and operated to the position (A) shown in Fig. 3, the wire (21) is pulled and the operating arm (18) swings upward in the plane of the paper. Be manipulated. In this case, the drive pulley (10
) and the center line connecting the rotation centers of the driven pulley (11) (
Along X), the linking member (2o) is pulled up to the upper right on the paper, and the operating arm (18) and the linking member (
The connection point (Y) with 2o) is lifted above the center line (X).

As a result, the bending link (16a) as shown in FIG.
, (16b), the first and second tensigon booleys (13a) and (13b) are expanded.

Then, by lifting the connection point (Y) above the center line (X), the weight of the first and second tension pulleys (13a), (13b), etc.
Connection point (Z) of refraction links (i6a) and (16b)
(corresponding to the point of refraction) is prevented from being displaced downward from above the center line (X).

When the above-mentioned state Q occurs, the spring (22) is stretched from its natural length state, so the bending link (16a) is
, (16b) is prevented from being displaced upward or downward from the center line (X).

As described above, the first and second tension pulleys (
13a) and (13b) are pushed apart by an equal distance from the center line (X), the tension on the transmission heald (12) is weakened, and the power from the drive pulley (10) is cut off. In other words, one of the left and right clutch levers (19a) or (1
9b) to the position (A) shown in FIG. 3 to cut off the power to either the left or right rear wheels (2), a turning operation or a manual push operation of the walk-behind lawn mower is performed.

The left and right rear wheels (2) are each equipped with a brake (not shown), and a linking rod (25) is installed across the brake control lever (24) and the control arm (18). .

As a result, the state shown in Fig. 2 (clutch lever (19)
a), (19b) are operated to position (A) in Fig. 3), then move the clutch levers (19a), (19b) to the third position.
When the grip is operated to the position (B) shown in the figure, the wire (21) is further pulled and the brake of the rear wheel (2) is applied via the operation lever (24). This results in
Can turn in a small radius.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of drawings]

The drawings show an embodiment of the tension clutch structure according to the present invention, and FIG. 1 is an overall side view showing the structure around the driving pulley, driven pulley, and transmission heald, and FIG. 2 shows the bending link removed from the state shown in FIG. 1. A side view showing the clutch disengaged state with upward displacement operation, Fig. 3 is an overall side view of the walk-behind lawn mower, Part 4 is a side view showing the conventional tension clutch structure, Fig. 5 is shown in Fig. 4 FIG. 7 is a side view showing a state in which the drive pulley is driven counterclockwise on the paper and power is transmitted to the driven pulley. (10)... Drive pulley, (II)...
...Followed Boono, (12)...Transmission heald,
(13a)...First tension pulley, (1
3b)...Second tension pulley, (15)
...Spring, (16a), (16b)...
... Refraction link, (22) ... Hane, (X)
...center line, (Z) ... point of refraction.

Claims (1)

[Claims] A transmission belt (12) is wound around a driving pulley (10) and a driven pulley (11) that can be driven in forward and reverse directions, and each of the tension side path and slack side path of the transmission belt (12) A pair of external tension pulleys (13a) and (13b) are provided on the outside so that they can freely come into contact with and separate from each other, and the first and second tension pulleys (13a)
, (13b) toward each other, and bendable bending links (16a), (16
b) the first and second tension pulleys (13a), (
13b), and the drive and driven pulley (
10), the bending point (Z) of the bending link (16a), (16b) along the center line (X) connecting both rotation centers of (11)
By moving the refractive link (16a),
, (16b) so that the first and second tension pulleys (13a) and (13b) can be forcibly separated, wherein the bending points of the bending links (16a) and (16b) (Z)
A single spring (22), which is tensioned or compressed by movement of the inflection point (Z) along the center line (X), biases the inflection point (Z) back onto the center line (X). Tension clutch structure attached to (Z).