JPS62125924A - Continuously variable transmission - Google Patents

Abstract

PURPOSE:To prevent occurance of engine stall during quick deceleration in which there occurs a remarkable response lag between the change of transmission gear ratio of a continuously variable transmission and the change of vehicle speed by disengaging the connection of a clutch device as the engine speed becomes below a predetermined value. CONSTITUTION:When the engine speed becomes below a predetermined value during quick deceleration, a signal from engine speed detecting means 8 is inputted to control means 7. According to the operational command of the control means 7, a solenoid 63 is operated to drain the pilot pressure applied to a spool 61 in the direction opposite to the urging force of a spring 62. This causes the spool 61 to receive the urging force of the spring 62 and the pilot pressure applied in the same direction of the urging force to interrupt the communication between a control valve 4 and a clutch device 10. As the result, an excessive load is applied from the non-stage transmission side to the engine side, avoiding extreme falling of the engine speed below the predetermined value, so that engine stall can be positively prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a continuously variable transmission mounted on a vehicle.

<Prior Art> Conventionally, continuously variable transmissions for vehicles include belt type and hydraulic type. A belt-type continuously variable transmission basically connects a driving pulley and a driven boolean with a belt, and makes one or both of the pulley faces movable to change the rotation radius of the belt to change the speed ratio (gear). ratio) is configured to change steplessly. In addition, there are various types of hydraulic continuously variable transmissions, and a representative example is a set of variable displacement pump pumps as disclosed in U.S. Pat. No. 2,830,468 and the drawings. motor unit and
It is equipped with a differential gear mechanism that distributes the input torque into hydraulic torque and mechanical torque generated by the pump motor unit, and a low clutch and a high clutch that change the torque distribution by the differential gear mechanism, and has a low range and a high range. By switching the connection and disconnection of the low clutch and the high clutch, and by changing the discharge amount of the pump side unit of the set of pump motor units in each range, the gear ratio can be changed steplessly to 1q. What he did is well known.

(Problem to be solved by the invention) By the way, in such a continuously variable transmission, the gear ratio changes automatically and continuously according to the magnitude of the vehicle speed; In reality, there is a response delay between the change in vehicle speed and the change in vehicle speed.

Especially if the vehicle speed suddenly decreases due to braking (
During sudden deceleration), this response delay becomes noticeable, resulting in an excessive load on the engine, resulting in an extremely low engine speed and engine stalling.

The present invention has been made in view of the above, and its purpose is to provide a countermeasure against the response delay between a change in gear ratio and a change in vehicle speed in a continuously variable transmission as described above. During sudden deceleration, when the response delay becomes significant, the clutch device shuts off the engine transmission line itself before the engine speed drops extremely due to the response delay, thereby preventing the engine from stalling. It is something to do.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention provides a stepless clutch device in which an engine output transmission path is provided with at least one clutch device capable of interrupting the transmission path. In the transmission, an engine rotation speed detection means detects the engine rotation speed, and a clutch release means receives a signal from the detection means and disconnects the clutch device when the engine rotation speed falls below a set rotation speed. The structure is equipped with the following.

(Function) With the above configuration, in the continuously variable transmission of the present invention, when the engine speed drops below the set speed during sudden deceleration where there is a noticeable response delay between the change in the gear ratio and the change in the vehicle speed, , the clutch release means activated in response to a signal from the engine speed detection means disconnects the clutch device and cuts off the engine output transmission path, causing an excessive load on the engine due to the above response delay. The rotational speed will not drop to an extremely low level, and engine stalling will be prevented.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a belt type continuously variable transmission according to an embodiment of the present invention, and this continuously variable transmission includes a continuously variable transmission mechanism 1 and a forward/reverse switching gear mechanism 2. The continuously variable transmission mechanism 1 includes a drive pulley 13 provided on an input shaft 12 connected to an engine drive shaft 11 via a hydraulic clutch device 10, and an output shaft 14 parallel to the input shaft 12. It has a driven pulley 15 provided above. The drive side pulley 13
has a fixed disc 13a formed integrally with the input shaft 12 or fixed to the input shaft 12, and a movable disc 13b disposed on the input shaft 12 so as to be slidable in the axial direction. However, a hydraulic seedling 13c for pushing the movable disc 13b in the axial direction is formed on the outside of the movable disc 13b. Further, the driven pulley 15 is formed integrally with the output shaft 14, or is formed on a fixed disk 1 fixed to the output shaft 14.
5a, and a movable disc 15b slidably disposed on the output shaft 14 in the axial direction, and a hydraulic chamber 15c for pushing the movable disc 15b in the axial direction is provided on the outside of the movable disc 15b. It is formed.

The drive side and driven side pulleys 13.15 each have a V-shaped groove 1 between the disks 13&, 13b or 15a, 15b.
3d and 15d, and both V-shaped grooves 13d and 15
A V-shaped belt 16 is passed between the parts d and d. and,
The hydraulic chamber 13c of the drive pulley 13 is supplied with hydraulic oil whose pressure is regulated according to a desired gear ratio or a volume of hydraulic oil determined according to assimilation, and the axial position of the movable disc 13b is determined. and the hydraulic chamber 15C of the driven pulley 15.
is adjusted in the same way as above.1. : The FIJ oil is supplied to push the movable disk 15b toward the fixed disk 15a and apply a predetermined tension to the belt 16, thereby keeping the belt 16 in a tensioned state and increasing its rotational radius (driving pulley 13). The gear ratio is continuously and steplessly changed by changing the radius of rotation on the V-shaped groove 13 side.

On the other hand, the forward/reverse switching gear mechanism 2 includes a forward drive gear 21 rotatably mounted on the output @14, and an output shaft 14.
A retraction drive gear 22 is provided on the top thereof and splined to rotate together with the output shaft 14. A multi-plate hydraulic clutch 23 is provided between the drive tooth widths 21 and 22, and when the clutch 23 is connected, the navigation drive gear 21 is connected to the output shaft 14 via the reverse drive gear 22. It is meant to be combined. Further, an intermediate shaft 24 is disposed parallel to the output shaft 14, and a forward intermediate gear 25, a backward intermediate gear 26, and an output gear 27 are mounted on the intermediate shaft 24 either integrally with the intermediate shaft 24 or intermediately. It is provided in fixed relation to the shaft 24. The forward intermediate gear 25 is a forward drive a
The output gear 27 is always in mesh with the m wheel 21, and the output gear 27 is always in mesh with the input gear 32 of the differential gear mechanism 31.

Further, as shown in FIG. 2, the reverse intermediate gear 26 is connected to the reverse drive gear 22 via an idler gear 28.
It is designed to mesh with the Above idler tooth 11!2
8 is rotatably supported on an idler shaft 29 parallel to the output shaft 14 and the intermediate shaft 24, and a hydraulic cylinder (not shown) provided at one end of the idler shaft 29.
With the two idler shafts, the above-mentioned reverse gear 22.26
It is provided so as to be movable between an operating position in which it meshes with the gears 22 and 26 and a non-operating position in which it disengages from the gears 22 and 26. Thus, during forward drive, the idler gear 28 moves to the non-operating position and the hydraulic clutch 23 is connected, thereby
The rotation of the output shaft 14 is transmitted from the backward layer 1 FIJ gear 22 to the intermediate shaft 24 via the forward drive gear 21 and the forward intermediate gear 25, while during backward drive, the idler gear 28 moves to the operating position, The hydraulic clutch 23 is disconnected, and the rotation of the output shaft 14 is thereby transferred from the reverse drive gear 22 to the idler gear 28 and the reverse intermediate gear 2.
6 to the intermediate shaft 24, and the intermediate shaft 24 is configured to rotate in the opposite direction to that during forward drive.

In the above-mentioned continuously variable transmission, a clutch device 10 (in which the connection between the input shaft 12 and the engine drive shaft 11 constituting the engine output transmission path cannot be separated, that is, the engine output transmission path can be cut off) is provided. The hydraulic circuit is shown in Figure 3. In this hydraulic circuit, an oil pump 5 is communicated with a clutch device 10 via a control valve 4, and the control valve 4 cuts off communication between the oil pump 5 and the clutch device 10 when the clutch device 10 is in the neutral range. While disconnecting the device 1o, when in a range other than the neutral range, the oil pump 5
The oil pump 5 and the clutch device ff110 are communicated with each other to connect the clutch device 10 while regulating the pressure of the hydraulic oil from the pump to a predetermined pressure.

In addition, the control valve 4 and the clutch device 10
An emergency valve 6 serving as a clutch release means for disconnecting the clutch device 10 when the engine speed drops below a set speed is interposed between the clutch device 10 and the engine speed. The emergency valve 6 includes a spool 61 that connects and disconnects communication between the control valve 4 and the clutch device 10.
, a spring 62 that biases the spool 61 in the communication blocking direction, and a solenoid 63 for draining the pylob 1 pressure that applies pressure on the spool 61 in the communication connection direction against the urging force of the spring 62. The operation of the solenoid 63 is controlled by a control means 7.

The control means 7 operates a solenoid 63 for a predetermined period of time when a signal from an engine rotation speed detection means 8 that detects the engine rotation speed is input and the engine rotation speed falls below a set rotation speed. The pilot pressure applied in the direction of the communication connection is drained.

Next, the operation of the above embodiment, particularly the operation of the emergency valve 6, will be explained. During normal driving, the solenoid 63 of the emergency valve 6 is not operated, and the spool 61 is connected to the spring 62. The control valve 4 is placed in a state (the state shown in the lower half of FIG. 3) in which the control valve 4 and the clutch device 10 are communicated with each other by receiving a pilot pressure applied in a direction opposite to the urging force of the clutch device 10. As a result, the clutch device ff110 receives hydraulic oil from the control valve 4 and is in a connected state, and the engine output is transmitted from the engine drive shaft 11 to the continuously variable transmission mechanism 1 side via the clutch device 10. In the continuously variable transmission mechanism 1, the speed is continuously and steplessly changed according to the medium speed.

On the other hand, if the engine speed drops below the set speed during sudden deceleration, a signal from the engine speed detection means 8 is input to the control means 7, and the solenoid 63 is activated based on the control means 70 activation command. However, by draining the pilot pressure applied to the spool 61 in the opposite direction to the urging force of the spring 62, the spool 61 receives the urging force of the spring 62 and the pilot pressure applied in the same direction as the urging force. The state shifts to a state where communication between the control valve 4 and the clutch device 10 is cut off (the state shown in the upper half of FIG. 3), and the clutch device 10 is disconnected. Therefore, changes in vehicle speed during sudden deceleration occur. Even if a noticeable response delay occurs between the change in the gear ratio by the continuously variable transmission mechanism 1, an excessive load is applied from the continuously variable transmission mechanism 1 side to the engine side, and the engine speed becomes extremely low. The engine speed will not drop below the set rotation speed, and engine stalling can be reliably prevented.

Moreover, the solenoid 6 of the emergency valve 6
The connection and disconnection of the clutch device 10 due to the operation of step 3 is limited to a relatively short period of time (about 5 seconds) until the change in the gear ratio starts to follow the change in vehicle speed, and after the change in the gear ratio starts to follow the change in vehicle speed, the clutch device 10 is disconnected again. Since it is connected, there is no problem with the continuous running of the vehicle.

It should be noted that the present invention is not limited to the above embodiments, but includes various other modifications.

For example, in the above embodiment, the emergency valve 6 is provided between the clutch device 10 and the control valve 4 as a clutch release means for disconnecting the clutch device 10 when the engine speed drops below the set speed. However, the control valve 40 may be configured to also function as a clutch release means.

Furthermore, in the above embodiment, the present invention was applied to a belt-type continuously variable transmission, but it is also possible to apply the present invention to a hydraulic continuously variable transmission equipped with a low clutch and a high clutch as described in the section (Prior art). can also be applied. In this case, the configuration may be such that at least one of the low clutch and the high clutch is disconnected when the engine speed drops below the set speed.

(Effects of the Invention) As described above, according to the continuously variable transmission of the present invention, when the engine speed drops below the set speed during sudden deceleration, the clutch releasing means receives a signal from the engine speed detecting means to release the clutch. Since the device is disconnected and the engine output transmission path is cut off, the engine speed will not drop significantly due to the response delay between changes in the gear ratio and changes in vehicle speed, and the engine will stall. can be reliably prevented from occurring.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is a sectional view of a belt-type continuously variable transmission, FIG. 2 is a sectional view taken along the IT-]I line in FIG. It is a hydraulic circuit diagram. 6...Emergency valve, 8...Engine speed detection means, 10...Clutch 1A position. Figure 3

Claims (1)

[Claims] (1) In a continuously variable transmission in which an engine output transmission path is provided with at least one clutch device capable of interrupting the transmission path, an engine speed detection means for detecting the engine speed; A continuously variable transmission comprising: a clutch release means for disconnecting the clutch device when the engine speed drops below a set speed in response to a signal from the clutch device.