JPS643009Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention mainly relates to an abnormal noise prevention device for a manual transmission in an automobile.

With conventional manual transmissions, when idling in neutral and with the clutch engaged,
Engine torque fluctuations sometimes caused abnormal noises such as rattles and rattles. This is caused by the bump between the meshing gears of the transmission, so if you reduce the bump, you can prevent noise to some extent, but
There was a natural limit to reducing the size of the bump. As a countermeasure, it was considered to prevent abnormal noise by applying drag resistance (a type of braking force) using a spring means to the rotating shaft and gears during idling, and suppressing engine torque fluctuations. but,
Abnormal noise is affected by viscous resistance, which changes as the temperature of the lubricating oil inside the transmission changes. In other words, when the temperature of the lubricating oil is high, the viscous resistance is small, making it easier to generate abnormal noises, and when the temperature of the lubricating oil is low, the viscous resistance is large, so the same viscous resistance becomes drag resistance of the gear, which causes abnormal noises. Occurrence is prevented.
Therefore, according to the above measures, irrespective of the magnitude of the viscous resistance of the lubricating oil, drag resistance is always provided to the shaft and gears, which results in extra drag resistance being provided especially when the temperature is low. Furthermore, according to this measure, by providing extra drag resistance to the shaft and gears even when the vehicle is not idling,
Coupled with the extra drag resistance when the oil temperature is low, the durability of the transmission mechanism, shift feeling,
This has had a negative impact on fuel efficiency, etc.

Therefore, in view of the above-mentioned conventional drawbacks, the purpose of this invention is to prevent the shaft and gears that rotate during idling of a manual transmission when the temperature of the lubricating oil in the transmission is high and when the transmission is in neutral. The present invention aims to provide an abnormal noise prevention device that can provide drag resistance, thereby improving the durability, shift feeling, fuel efficiency, etc. of a transmission mechanism.

This invention aims to achieve the above object by shifting the shift fork for moving the hub sleeve of the synchronized mesh mechanism in a manual transmission only when the lubricating oil temperature is high and when the gear is in neutral. This is to apply the pressing force of the synchronized mesh mechanism.

An embodiment of this invention will be described below with reference to the drawings. In FIG. 1, which shows a part of a manual transmission for an automobile in cross section, an output shaft 2 is rotatably suspended horizontally in a case 1 of the transmission. Output shaft 2 has driven gear 3
is rotatably provided. driven gear 3
is engaged with a counter gear 4 of a counter shaft (not shown). The countershaft rotates in response to torque transmission from the engine during idling in a neutral state with the clutch connected, and rotates the driven gear 3 via the counter gear 4. Output shaft 2
A synchromesh mechanism 5 is disposed adjacent to the driven gear 3.

The synchromesh mechanism 5 is well known, but briefly, when the hub sleeve 6 is shifted from the neutral position shown in the figure to the right along the clutch hub 7 on the output shaft 2. , at the beginning of its movement, the synchronizer ring 9 is pressed against the tapered cone surface 11 of the synchronizing cone 10 of the driven gear 3 by the shifting key 8 . Due to this mutual frictional contact between the synchronizing ring 9 and the synchronizing cone 10, the output shaft 2
and the driven gear 3 are synchronized. After this synchronizing action, the hub sleeve 6 is further shifted, and finally the hub sleeve 6 is spline-fitted to the synchronizing ring 9 and the synchronizing cone 10 to connect the clutch hub 7 and the synchronizing cone 10. The shift is completed by connecting in series.

A shift fork 12 for shifting the hub sleeve 6 of the synchromesh mechanism 5 is slidably provided on a fork shaft 13. The forkshaft 13 is installed in the case 1 in parallel with the output shaft 2 so as to be axially movable. Left and right snap springs 14 and 15 located on both left and right sides of the shift fork 12 are disposed on the fork shaft 13, and the shift fork 12 and the right snap spring 1 are arranged on the fork shaft 13.
A holding sleeve 16 is slidably fitted between the shift fork 12 and the left snap spring 14, and a first sleeve 17 and a second sleeve 18 are slidably fitted in series between the shift fork 12 and the left snap spring 14. equipped. Thereby, the sliding amount S of the shift fork 12 and each of the sleeves 16 to 18 between the two snap springs 14 and 15 is ensured. A retaining spring 19 made of a normal coil spring is interposed between the shift fork 12 and the right snap spring 15 in a state where it is loosely inserted into the retaining sleeve 16. A flange 20 is formed at the right end of the second sleeve 18 adjacent to the left snap spring 14, and a flange 20 is formed between the flange 20 and the shift fork 12 and between the flange 20 and the right snap spring 15, respectively. Coil springs (referred to as SMA springs in the present invention) 21 and 22 made of a shape memory alloy are attached to each sleeve 17 and 1.
It is inserted loosely into 8. Both SMA springs 17 and 18 utilize the characteristics of a shape memory alloy that can recover its shape by repeating a preset shape depending on a certain temperature.
The spring 21 reduces the viscous resistance of the lubricating oil in the case 1 to a predetermined value or less. In other words, when the oil temperature rises to a predetermined temperature or higher, the oil expands (recovers its shape) under the influence of this temperature. second
The SMA spring 22 is incorporated into an electrical circuit 23 that includes a neutral sensing switch 24 that switches on when in neutral.
When the spring 22 is switched on, the spring 22 itself is heated and restored to its shape. This second SMA spring 2
The transformation temperature of the second SMA spring 21 is set higher than the transformation temperature of the first SMA spring 21, and does not expand at about the temperature at which the lubricating oil is heated. However,
The elastic force FR of the holding spring 19, the shape recovery elastic force FT of the first SMA spring 21, and the second
The shape recovery elastic force FN of the SMA spring 22 is set to satisfy the following relationships: FR>FT FR>FN FR<FT+FN.
Note that the electric circuit 23 includes a battery 25 and an electric resistor 26.

In the noise prevention device described above, when the lubricating oil rises above a predetermined temperature and the viscous resistance decreases below a predetermined value, and the transmission is placed in neutral, the first SMA spring 21 is affected by the oil temperature. as well as the second SMA.
Spring 22 is a neutral sensing switch 24
It is elongated by being heated with electricity in the switch. The sum of the shape recovery elastic forces FT and FM of both SMA springs 21 and 22 exceeds the elastic force FR of the retaining spring 19 (see the above relational expression);
The shift fork 12 is shifted on the fork shaft 13 to the right in the drawing. Accordingly, the hub sleeve 6 is shifted, and as described above, the synchronizer ring 9 is brought into frictional contact with the synchronizing cone 11 via the shifting key 8 (see FIG. 2). Therefore, when idling in a neutral state with the clutch connected, the driven gear 3 rotates in response to torque transmitted from the engine via the counter gear 4 on the counter shaft, but the output shaft 2 naturally does not rotate. Because I haven't done it,
This frictional contact between the non-rotating output shaft 2 and the rotating dripped gear 3 imparts drag resistance to the driven gear 3, resulting in abnormal noise caused by bumping between the gears. will be prevented. Therefore, the shift fork 12 only shifts by a sliding amount S, and this sliding amount S is preset to an amount that does not reach the completion of the shift connecting the output shaft 2 and the driven gear 3. shall be.

In addition, when both SMA springs 21 and 22 do not recover their shape, or when either SMA spring 21, 22
When only the springs 21 and 22 have recovered their shape, the elastic force FR of the retaining spring 19 is greater than each shape recovery elastic force FT or FN, so the shift fork 12 is held at the neutral position as shown in FIG. In other words, when the temperature of the lubricating oil is below a predetermined temperature (when the viscous resistance is greater than a predetermined value),
Alternatively, when the transmission is in a state other than neutral, or when both are in a combined state, the pressing force of the synchromesh mechanism 5 related to noise prevention does not work.

That is, this invention shifts the shift fork for moving the hub sleep of the synchronized mesh mechanism in a manual transmission only when the lubricating oil temperature is high and is in neutral, thereby achieving synchronized meshing. This applies the pushing force of the mechanism to provide drag resistance to the rotating shaft and gears when in neutral, which prevents abnormal noise and improves the durability and shift feeling of the transmission mechanism compared to conventional ones. , fuel efficiency, etc. can be improved.

[Brief explanation of drawings]

Figures 1 and 2 are cross-sectional views showing an embodiment of the noise prevention device of this invention, including a synchronized mesh mechanism in a manual transmission for an automobile. Figure 1 is the state before operation, and Figure 2 is indicates the operating state. 5... Synchronous mesh mechanism, 6... Hub sleeve, 12... Shift fork, 13... Fork shaft, 19... Retention spring, 21...
First SMA spring, 22... Second SMA spring, 23... Electric circuit, 24... Neutral sensing switch, S... Slide amount.

Claims (1)

[Scope of utility model registration request] A shift fork for shifting the hub sleeve of a synchronized mesh mechanism in a manual transmission is provided on the fork shaft so as to be slidable by a predetermined sliding amount, and the shift fork is set at a neutral position by a retaining spring, and the shift fork is is equipped with a first SMA spring and a second SMA spring made of shape memory alloy, and the first SMA spring is designed so that it can recover its shape when the lubricating oil in the transmission rises to a predetermined temperature or higher. The second SMA spring is incorporated into an electric circuit including a neutral sensing switch that is turned on when the switch is turned on, and the second SMA spring is formed so that it can recover its shape by being heated with electricity by the switch. When both springs recover their shape, the shift fork slides on the fork shaft against the retaining spring due to the cooperation of the shape recovery forces of both, and the pressing force of the synchronized mesh mechanism acts. Features: Abnormal noise prevention device for manual transmissions.