JPH01238739A - Gear type transmission - Google Patents

Abstract

PURPOSE:To prevent application of excessive torque to a speed change gear by maintaining a gear shift mechanism in non-transmission condition when a torque transmission/non-transmission condition selecting mechanism selects the non-transmission conditions in such a case that an input shaft or output shaft revolution number satisfies specific conditions. CONSTITUTION:When the number of revolutions of a counter shaft 1 or an output shaft 10 transmitted through a governer drive gear 30, that is an engine speed increases to or above a specified level, a governer weight 28 pushes a guide shaft 12 upwards. When a shift drum 13 is at a neutral position at this time, a stopper pin 18a ascends/descends together with the shaft 12, and engages with a branch groove of a second guide groove 16 to prohibit the rotation of the drum 13. As a result, gear change does not work, and non-transmission conditions under which the torque of the input shaft is not transmitted to the shaft 10 are retained. It is thus possible to prevent application of excessive torque to a speed change gear without using a torque limiter.

Description

[Detailed description of the invention] technical packaging The present invention relates to a gear type transmission.

BACKGROUND TECHNOLOGY A gear type transmission changes the rotation speed and torque of the input shaft by changing the combination of a plurality of transmission gears that are provided between an input shaft and an output shaft and mesh with each other. Depending on the situation, the relay output is relayed from the output shaft or torque transmission is cut off, or there is a large difference between the rotation speed ratio between the input shaft and output shaft and the gear ratio of the selected gear. In some cases, when a gear change is performed, excessive torque momentarily acts on the transmission gear, resulting in an unfavorable shift feeling.

Therefore, in order to improve the shift feeling caused by the above-mentioned excessive torque, a torque limiter using a friction plate is installed between the input shaft and the output shaft. For example, Japanese Patent Application Laid-open No. 165058/1983 discloses a gear shifter in which an excessive torque exceeding a predetermined value is not applied to a transmission gear due to the displacement of a friction plate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a gear type transmission that can prevent excessive torque from being applied to a transmission gear without providing a torque limiter and can improve shift feeling.

In order to achieve the above-mentioned object, in the gear type transmission according to the present invention, the selection mechanism for selecting the torque relay state and the non-relay state is such that the rotation speed of at least one of the input shaft and the output shaft satisfies a predetermined condition. When the torque non-relay state is selected in the meantime, a holding means is provided to hold the selection mechanism in that state.

The selection mechanism is composed of a shift fork that is movable between a torque relay position and a non-torque relay position, and a cam member that positions the shift fork as a cam follower. A stopper member that locks the cam member when the member or shift fork reaches a position where the torque is not relayed, and a stopper member that moves the cam member in a predetermined direction when the rotational speed of the input shaft or output shaft exceeds a predetermined rotational speed. It is possible to comprise a biasing means for biasing.

EXAMPLE Hereinafter, an example in which the present invention is applied to a transmission for a motorcycle will be described with reference to the accompanying drawings.

As shown in the figure, counter gears 2 and 3 are fitted onto the countershaft 1 so as to rotate relative to the countershaft 1, and the counter gears 2 and 3 are fitted with an engine mounted on a motorcycle (see the figure). Torque is transmitted from the input shaft (not shown) through a main gear (not shown) fixed to an input shaft (not shown). The same number of main gears as the counter gears 2 and 3 are provided, and the main gears and the counter gears 2 and 3 are always in mesh with each other. If a reverse idle gear (not shown) is interposed between the main gear and the counter gear 3, the counter gear 3
will now rotate in the opposite direction to counter gear 2,
It can be used as a reverse gear.

The shifter 5 is located between the counter gears 2 and 3, and the shifter boss 6 is located between the counter gears 2 and 3.
It has a spline fit through it. A circumferential groove 5a is cut into the outer peripheral surface of the shifter 5, and the tip of the shift fork 7 is engaged with the circumferential groove 5a. Dowels 5b and 5C protrude from both end faces of the shifter 5 facing the counter gears 2 and 3, and the shift fork 7 causes the shifter 5 to slide in the central axis direction of the counter shaft 1, and Dowel holes provided a or 3a
The dowel 5b or 5C is fitted into the dowel 5b or 5C.

When the dowel 5b or 5c fits into the dowel hole a or 3a, the rotational torque of the counter gear 2 or 3 is transferred to the shifter 5. Counter shaft 1 via shifter boss 6
transmitted to.

A drive gear 8 that rotates together with the countershaft 1 is fixed to the countershaft 1.
is the final gear 11 spline-fitted to the output shaft 10.
It is mated with. Therefore, as described above, when rotational torque is transmitted to the countershaft 1, the rotational torque is transmitted from the countershaft 1 to the output shaft 10 via the drive gear 8 and the final gear 11. Further, the rotational torque is transmitted from the output shaft 10 to a drive wheel (not shown), causing the drive wheel to rotate.

A shift fork 7, which is engaged with the shifter 5 at its tip, is slidably supported on a guide shaft 12. A pin portion 7a is formed on the shift fork 7 to protrude in the radial direction with respect to the central axis of the guide shaft 12, and the pin portion 7a is formed on the shift drum 1 disposed parallel to the guide shaft 12.
The first guide groove 1 is carved on the outer peripheral surface of 3.
5 is engaged. The first guide groove 15 is bent in three stages as shown in FIG. 2 in the circumferential direction of the shift drum 13 (arrow C
direction), the pin portion 7a of the shift fork 7 traces the first guide groove 15 by rotating the shift drum 13. That is, the shift drum 13
acts as a cam member and positions the shift fork 7, which acts as a cam follower. As a result, the shift fork 7 is slid in the direction of the central axis of the guide shaft 12, and drives the shifter 5 to move the dowel 5b or 5.
C is fitted into and removed from dowel hole a or 3a. Incidentally, in order to rotate the shift drum 13, a lever (not shown) is attached to the end portion 13a of the shift drum 13, and the lever can be rotated by swinging the lever. Alternatively, the rotation of another shaft (not shown) may be transmitted via a transmission means such as a gear to indirectly rotate the shaft.

In addition to the first guide groove 15, a second guide groove 16 is carved on the shift drum 13. As shown in FIG. 2, the second guide groove 16 extends in the circumferential direction of the shift drum 13 and has branch grooves 16a that branch in the direction of the central axis of the shift drum 13. A pin portion 18 a of a stopper 18 fixed to the guide shaft 12 with a set bolt 17 is engaged with the second guide groove 16 . Note that a lock plate 20 prevents the set bolt 17 that fixes the stopper 18 to the guide shaft 12 from loosening.

The guide shaft 12 is supported by the housing 21 so as to be movable in the direction of its central axis.

Further, a pin 22 is press-fitted into the guide shaft 12 at right angles to its central axis, and this pin 22 is inserted into the housing 21.
The guide shaft 12 is prevented from rotating by engaging with a groove 21a carved along the central axis direction of the guide shaft 12.

The guide shaft 12 is urged downward in the drawing by a coil spring 23 at one end, and a centrifugal governor 25 is provided at the other end. The centrifugal governor 25 includes a governor holder 27 rotatably attached to the housing 21 with bolts 26, and a governor weight 28 pivotally attached to the governor holder 27. A gear 27a that meshes with a governor drive gear 30 is formed on the outer side of the governor holder 27, and the rotation of the engine is transmitted to the governor holder 27 via the governor drive gear 30. Therefore, when the engine speed increases above a predetermined rotation speed, the governor weight 28 is driven to spread outward by centrifugal force, and the end 28a of the governor weight 28 resists the biasing force of the coil spring 23 and moves toward the guide shaft 12. Press upwards on the drawing. At this time, if the shift drum 13 is in the neutral position shown in FIG. 2(A), the pin portion 18a of the stopper 18 fixed to the guide shaft 12 moves together with the guide shaft 12 and moves to the neutral position shown in FIG. 2(B). As shown, it engages with the branch groove 16a of the second guide groove 16. As the pin portion 18a engages with the branch groove 16a in this manner, the shift drum 13 is locked to the pin portion 18a in the rotating direction, and the shift drum 1
3 rotation is prohibited. Therefore, a gear change cannot be performed, and a torque non-relay state is maintained in which the torque of the input shaft is not relayed to the output shaft.

When the rotation of the engine decreases, the biasing force of the coil spring 23 overcomes the pressing force of the governor weight 28, the guide shaft 12 is returned to the lower part of the drawing, and the pin portion 18a of the stopper 18 is pulled out from the branch groove 16a, so that the shift drum 1
This allows for 3 rotations and gear changes.

FIG. 2(C) or (D) shows the first guide groove 15 and second guide groove 16 when the dowel 5b or 5C of the shifter 5 is fitted into the dowel hole a or 3a of the counter gear 2 or 3. The pin portions 7'a and 18a are shown engaged respectively. When the rotation of the engine increases to a predetermined rotation or higher in each state, the pin portion 18 of the stopper 18
Although a is pressed by the governor weight 28, it does not engage with the branch groove 16a, and this state (torque relay state in which the torque of the input shaft is relayed to the output shaft) is maintained, but when the engine speed exceeds a predetermined speed. When the shift drum 13 is rotated while being raised to the neutral position shown in FIG. 2(A), the pin portion 18a of the stopper 18
engages with the branch groove 16a as shown in FIG. 2(B).

Therefore, the shift drum 13 is held at the neutral position, and the shift drum 13 cannot be rotated unless the rotation of the engine is lowered below a predetermined rotation.

As shown in FIG. 1, a tappet 29 is provided between the governor weight 28 and the guide shaft 12, and the two tappets are rotatably attached to the guide shaft 12 via bearings. . In this way, by providing the tappet 29 so as to be rotatable, the difference in rotation between the non-rotating guide shaft 12 and the rotating governor weight 28 can be alleviated, and wear on the end portion 28a of the governor weight 28 can be suppressed. .

In the embodiment described above, the rotation of the engine is transmitted to the governor holder 27 via the governor drive gear 30, so when the engine rotation speed rises above a predetermined rotation speed, the guide shaft 12 is rotated by the action of the governor weight 28. Although it is configured to be pressed upwards in the drawing,
If the rotation of the countershaft 1 or the output shaft 10 is transmitted to the governor holder 27 via the governor drive gear 30, the rotation of the countershaft 1 or the output shaft 10 is transmitted to the governor holder 27 via the governor drive gear 30.
The guide shaft 12 can be pushed upward in the drawing when the rotation of the torque relay state exceeds a predetermined rotation speed, and in this case, switching from the torque non-relay state to the torque relay state can be regulated.

Further, an overrev switch 31 is provided in a portion of the housing 21 that supports one end of the guide shaft 12, and when the engine speed increases to a predetermined speed or higher, the guide shaft 12 is activated by the action of the centrifugal governor 25. When it is moved upward in the drawing, it is pushed by the end of the guide shaft 12 and turned on. If an indicator lamp (not shown) that lights up in conjunction with the operation of the overrev switch 31 is installed on the motorcycle's meter panel, gear changes will not be possible because the engine speed is higher than the predetermined speed. It is possible to notify the driver of the current condition.

FIG. 3 shows an embodiment using a centrifugal governor different from that shown in FIG. In this embodiment, a governor plate 3 is attached to the end of the guide shaft 12 on the side where the centrifugal governor is provided.
3 is fixed with a nut 35, and a spherical weight ball 36 is interposed between the governor plate 33 and the governor holder 27, and the governor holder 2 rotates according to the engine speed.
7 rotates the weight ball 36, and when the weight ball 36 moves outward due to centrifugal force, it presses the guide shaft 12 upward in the drawing via the governor plate 33.

Note that the other configurations are the same as those of the embodiment shown in FIG. 1, so the same reference numerals are given to the same or equivalent parts, and the explanation thereof will be omitted.

Furthermore, in Fig. 4, a solenoid 37 is used instead of the centrifugal governor.
An example will be shown in which the guide shaft 12 is driven using the following. As shown, a solenoid 37 is provided at the lower end of the guide shaft 12 and fixed to the housing 21 . A current is supplied to the solenoid 37 from a current supply circuit (not shown) when the engine speed reaches a predetermined speed or higher. The solenoid 37 supplied with current urges the guide shaft 12 upward in the drawing. Other configurations and operations are similar to those of the embodiment shown in FIG. 1, so the same components are given the same reference numerals and their explanations will be omitted. Note that when it is decided that the guide shaft 12 is driven by the solenoid 37, the rotation speeds of the input shaft and the output shaft 10 are detected and the input shaft and It is also possible to configure so that current is supplied to the solenoid 37 to bias the guide shaft 12 when the difference in rotational speed from the output shaft 10 exceeds a predetermined value. Further, in FIG. 4, the guide shaft 12 is directly driven by the solenoid 37, but a plunger may be provided in the solenoid 37 and the movement of the plunger may be transmitted to the guide shaft 12 via a lever.

As described in detail of the invention, in the gear type transmission according to the present invention, the selection mechanism for selecting the torque relay state and the non-relay state is configured so that the rotation speed of at least one of the input shaft and the output shaft satisfies a predetermined condition. If you select the torque non-relay state while
The structure includes a holding means for holding the gear shift mechanism in that state. Therefore, if the difference between the rotation speeds of the input shaft and output shaft is greater than a predetermined value, switching from the torque non-relay state to the torque relay state (shift operation) is prevented, and the difference between the rotation speeds of the input shaft and output shaft is prevented. Unless the torque falls below a predetermined value, switching from the torque non-relay state to the torque relay state is only possible. Therefore, switching from the torque non-relay state to the torque relay state when the difference in rotational speed between the input shaft and the output shaft exceeds a predetermined value is prevented, and excessive torque is prevented from being applied to the transmission gear. This can be prevented without using a torque limiter. Furthermore, since it is no longer necessary to use a torque limiter, it is possible to reduce the size and weight.

The selection mechanism is composed of a shift fork that is movable between a torque relay position and a non-torque relay position, and a cam member that positions the shift fork as a cam follower. A stopper member that locks the cam member when the shift fork reaches a torque non-relay position, and a stopper member that is attached in a predetermined direction when the rotation speed of the input shaft or output shaft exceeds a predetermined rotation speed. When configured with a biasing means for applying force, the above-mentioned effects can be obtained with a simple mechanical configuration.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a gear type transmission according to the present invention, Fig. 2 is a developed view of the first and second guide grooves carved in the shift drum, and Fig. 3 is a centrifugal transmission different from Fig. 1. FIG. 4 is a sectional view showing an embodiment of the invention using a centrifugal governor, and FIG. 4 is a sectional view showing an embodiment of the invention using a solenoid instead of a centrifugal governor. Explanation of symbols for main parts 1... Counter shaft 2.3... Counter gears 2a, 3a... Dowel hole 5... Shifter 5a... Circumferential groove 5b, 5c... Dowel 7 -...Shift fork 7a...Pin portion 8...Drive gear 10...Output shaft 11...Final gear 12...Guide shaft 13... ...Shift drum 15...First guide groove 16...Second guide groove 18...Stopper 18a...Pin portion 21...Housing 23...Coil spring 25... ... Centrifugal governor 37 ... Solenoid applicant Honda Motor Co., Ltd.

Claims (2)

[Claims] (1) A gear type transmission having a selection mechanism for selecting a torque relay state in which the torque of the input shaft is relayed to the output shaft and a torque non-relay state in which the torque of the input shaft is not relayed to the output shaft, When the selection mechanism selects a torque non-relay state while the rotational speed of at least one of the output shafts satisfies a predetermined condition, the gear includes a holding means for holding the selection mechanism in that state. type transmission. (2) The selection mechanism includes a shift fork that is movable between a torque relay position and a torque non-relay position, and a cam member that positions the shift fork as a cam follower, and the holding means is attached in a predetermined direction. a stopper member that locks the cam member when the cam member reaches a position where the shift fork is positioned at the torque non-relay position in a biased state; The gear type transmission according to claim 1, further comprising a biasing means for biasing the stopper member in the predetermined direction when the stopper member is in the predetermined direction.