JPH0488260A - Switching device for gear mechanism - Google Patents

Abstract

PURPOSE:To reduce the dimension of a switching device for a gear mechanism and prevent the shift to a position where an operating rod can not be operated, by allowing a cam on one side of a fixed member to shift an operating rod in the axial direction when a cam on the other side is turned to one side when a turning member is turned to the other side. CONSTITUTION:When an arm 18 is turned to a normal revolution position, only the second cam 15 operates to press the stage part D of an operating rod 8a, which is shifted rightward by the quantity corresponding to the lift. Accordingly, an operating member 8 shifts rightward against the springy force of a belleville spring 7j, and advances a pressing plate 7f rightward by the load set by the belleville spring 7j, and a direct connection clutch 4 is connected. When the arm 18 is turned to the position for reverse revolution from a neutral position, the direct connection clutch 4 returns to an initial position, and the first cam 14 operates to press a nut N screwed with the operating rod 8a, and shifts the nut N leftward by the quantity corresponding to the lift. Accordingly, the operating member 8 presses a pressing plate 7e through pins 7k and 7k, and advances the pressing plate 7e leftward, and an auxiliary clutch 5 is engaged.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is mainly concerned with driving a small agricultural tractor by switching its tracks in both forward and reverse directions, or by changing speed, and switching the small tractor between forward and reverse movement. The present invention relates to a switching device suitable for changing gears.

[Conventional technology]

In general, gear mechanisms used for shifting speeds and forward/reverse switching in small tractors and other self-propelled agricultural machines have a multi-disc clutch for each gear train, which is operated by hydraulic cylinders and cams installed inside the gear case. Disengagement is being carried out.

Moreover, a small ball cam mechanism is often used when only engaging and disengaging one clutch.

[Problem to be solved by the invention]

However, with conventional systems in which the cam mechanism for engaging and disengaging the multi-disc clutch is installed inside the gear case, if a large-capacity multi-disc clutch is used, the gear case that houses it becomes large. .

Furthermore, it is difficult to engage and disengage two clutches using a ball cam mechanism that is relatively small and can provide a large operating force.

[Means to solve the problem]

The purpose of this invention is to solve the above-mentioned problems and provide a switching device for a gear mechanism that can operate reliably and provide a large operating force. They are arranged symmetrically back to back on the shaft ends of the transmission shafts that are pivotally supported in the case, and an actuation plate that engages and disengages the friction clutches is placed between both friction clutches, and the actuation plate is inserted into the shaft hole of the transmission shaft. In a gear mechanism in which the operating rod is fixed to an operating rod that extends outside the gear case through the gear case, and the operating rod is connected to a cam mechanism provided on the outer surface of the gear case, the two cams forming the cam mechanism are supported on the outer surface of the gear case. The rotating member is configured by a member and rotating members disposed on both sides of the member, and the rotating member is locked to the operating rod so that it can be rotated between the neutral position and the other side by the gear change lever, and the rotating member For example, when the fixed member is rotated in one direction, the cam formed on one side of the fixed member moves the operating rod in the axial direction, and when the fixed member is rotated in the other side, the cam formed on the other side moves the operating rod in the axial direction. It has characteristics.

[Effect]

When the gear shift lever is rotated from the neutral position to one side, a cam disposed on one side of the fixed member operates to move the operating rod in the axial direction. Further, when the gear shift lever is rotated to the other side, the cam disposed on the other side operates to move the operating rod in the opposite direction.

〔Example〕

The present invention will be explained below with reference to illustrated embodiments. In the figure, 1 is a gear case, which includes a drive shaft 2 and a driven shaft 3.
are coaxially arranged and bearing. Both shafts 2.3 are directly connected and disconnected via a direct coupling clutch 4, or an auxiliary clutch 5 and a reduction gear train 6 for speed change or forward/reverse rotation.
a and an auxiliary shaft 6 having a reverse gear train 6b. In this embodiment, one end 6C of the auxiliary shaft 6 is taken out to the outside of the gear case 1 and used to drive the agricultural working machine. Further, in this embodiment, the auxiliary clutch 5 and the auxiliary shaft 6 are used to change the speed of the drive shaft 20, which is a transmission shaft, or to switch between forward and reverse directions, as is conventionally known.

A direct coupling clutch 4, an auxiliary clutch 5, and i are arranged coaxially on the drive shaft 2, and are configured such that when one is engaged, the other is released in an antagonistic manner. That is, when the direct coupling clutch 4 is engaged, the auxiliary clutch 5 is released, the drive shaft 2 and the driven shaft 3 are directly coupled, and the driven shaft 3
is given rotation at the same speed in the same direction as the drive shaft 2. Further, when the auxiliary clutch 5 is engaged, the direct coupling clutch 4 is released, and the auxiliary shaft 6 having a reduction gear train 6a and a reverse gear train 6b is interposed between the drive shaft 2 and the driven shaft 3. 3
is given a decelerated rotation in the opposite direction to the drive shaft 2.

Note that 31 is an input shaft connected to a prime mover (not shown), and drives the drive shaft 2 via a gear train 32.

Detailed description of the deceleration clutch 4 and the auxiliary clutch 5 will be as follows.
They have an outer ring 7 driving friction plates 7a, 7a.

The outer ring τ extends integrally with the flange 7b and is mounted on the drive shaft 2 provided with a shaft hole. On the inner surface of the outer ring 7 are pressure receiving plates 7d, 7d whose retreat is prevented by circlips 7c, 7c.
and pressing forces 1i7e and 7f that advance and retreat toward it are supported, and press and release the friction plates 7a and 7a arranged between them. The pressure receiving plates 7d, 7d and the pressing plate 7
e, 7 [, as is well known, has a protrusion 7g formed protruding on the outer circumferential surface engaged with an axial slit 7h formed in the outer ring 7, and is movable only in the axial direction and rotates integrally with it. let

The friction plates 7a, 7a have engagement teeth formed on their inner peripheries, and are spline-engaged with the shafts protruding in the axial direction from the gears of the reduction gear train 6a, and the pressure plates 7e, 7f are connected to the pressure receiving plates 7d, 7
When it advances toward point d, it is compressed and the clutch engages, driving the gear of the deceleration train 6a at the same speed as the outer wheel 8.

The pressing plates 7e and 7f are moved back and forth by the positive cam mechanism 9 via the actuating member 8 interposed between them and the actuating rod 8a connected to the actuating member 8.

That is, the actuating member 8 is loosely fitted to the drive shaft 2, and is pressed and fixed to a collar 2a provided on the drive shaft 2 by disc springs 7j, 7j. Similarly, the pressing plate 7f is loosely fitted onto the drive shaft 2 and prevented from moving to the right by the circlip 2b.

2c, 2c are thrust bearings. 7k and 7 are push bottles slidably fitted and supported by the flange 7b, and are interposed between the push plate 7e and the actuating member 8.

The positive cam mechanism 9 includes rotating members 12 provided on both sides of a lid-shaped fixing member 11 fixed to the outer surface of the gear case 1 with bolts 10.
．． 13, and a first cam 14 and a second cam 15 formed therebetween. The rotating member 12 and the other rotating member 13 are slidably fitted to the end of the operating rod 8a. In other words, the distance between the step provided at the end of the operating rod 8a and the nut N is determined by the distance between the first and second end surfaces of the two rotating members 12 and 13 when the arm 18, which will be described later, is in the neutral position. Both cams 14
．． 15 is made larger by the lift height H of the rotating member 12.
13 has a concave-convex engagement 20 on the end face like an Oldham joint,
FIG. 3 shows the characteristics of both cams 14, 15, which are connected to each other so as to be movable in the axial direction and rotate integrally. In the figure, the right half shows the first cam 14, and the left half shows the second cam 15. As is clear from the figure, each cam 14, 15 has a lifting height H, and the operating rod 8a can be moved a distance equivalent to the lifting height H from the neutral position to the shift position.

Note that 16 is a steel ball.

An arm 18 is attached to the rotating member 12 by bolts 17, and two rods 19 and 19 are pivotally connected to both ends of the arm 18, the other end of which is connected to a speed change lever (not shown). As shown in FIG. 2, the arm 18 rotates between a normal rotation position on one side and a reverse rotation position on the other side with the neutral position in between.
Accordingly, when the rotating member 12 is rotated to the reverse rotation position, the second cam 15 shifts the operating rod 8a to the right in FIG. Shift to the left.

Next, the operation of this embodiment will be explained. First, when the arm 18 is in the neutral position, the first cam 14 and the second cam 15 are both inactive. That is, the actuating member 8 is pushed back to the left by the disk spring 7j to release the direct coupling clutch 4, and loosely abuts the push pins 7k, 7k, keeping the auxiliary clutch 5 disengaged as well.

When the transmission lever is operated to rotate the arm 18 to the normal rotation position, only the second cam 15 operates and presses the stepped portion of the operating rod 8a, lifting the operating rod 8a by an amount corresponding to the lifting height H. move it only to the right. That is, the actuating member 8 moves to the right against the elasticity of the disc spring 7j, moves the press plate 7f to the right under the load set by the disc spring 7j, and connects the direct coupling clutch 4. Therefore, the rotation of the drive shaft 2 is directly transmitted to the first driven shaft 3.

Next, when the arm 18 is rotated from the neutral position to the reverse position by the transmission lever, the direct coupling clutch 4 returns to the initial position, and the first cam 14 is activated and is screwed into the operating rod 8a. The nut N is pressed to move it to the left by an amount corresponding to the lifting height H. Accordingly, the actuating member 8 pushes the pressing plate 7e via the push pins 7k, 7k, advances to the left, and engages the auxiliary clutch 5. As a result, the direct coupling clutch 4 is released and the auxiliary clutch 5 is engaged, so that the rotation of the drive shaft 2 is decelerated and reversed, and the driven shaft 3
transmitted to.

〔Effect of the invention〕

As described above, the present invention is configured such that the two friction clutches 4.5 can be engaged and disengaged by moving the operating rod 8a common to both clutches in the axial direction, and the positive cam mechanism 9 is configured to move the operating rod 8a.
Since the two cams 14 and 15 are arranged on both sides of the fixing member 11 supported on the outer surface of the gear case 1, the structure is simple and the device can be miniaturized. In addition, the operating rod 8a
This has the effect of easily preventing the disc springs 7'', 7j, and others from moving to a position where they are not operated due to the axial force received from the friction clutch 4.5.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a cross-sectional view showing the neutral state, the second view is a cross-sectional view showing the forward state, and FIG. 3 is a cross-sectional view showing the backward state. 4-direct clutch, 5-auxiliary clutch, 7e,
7f-pressing plate, 8-actuating member, 8a-actuating rod,

Claims (1)

[Claims] Two friction clutches belonging to two gear systems are arranged symmetrically back to back on the shaft end of a transmission shaft supported by a gear case, and the actuating plates for engaging and disengaging the friction clutches are arranged symmetrically on the shaft ends of the transmission shafts supported by the gear case. A gear mechanism in which the actuating plate is fixed to an actuating rod extending outside the gear case through the shaft hole of the transmission shaft, and the actuating rod is coupled to a cam mechanism provided on the outer surface of the gear case. The two cams are composed of a fixed member supported on the outer surface of the gear case and rotating members arranged on both sides of the fixed member, and the rotating member is engaged with the operating rod and is rotated between the neutral position by the gear shift lever. When the rotating member is rotated to one side, the cam formed on one side of the fixed member is rotated, and when the rotating member is rotated to the other side, the cam formed on the other side is rotated. A switching device that moves the operating rod in the axial direction.