JPH081245B2 - Automatic transmission - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic transmission for an automobile, and more particularly to a multi-clutch multi-stage automatic transmission, which is intended to reduce shifting shock by smoothing a switching operation. Automatic transmission.

As an automatic transmission for an automobile, there are a gear transmission mechanism such as a planetary gear that is always in mesh with each other, and a friction engagement mechanism that switches the gear ratio by fixing or releasing each part of the gear transmission mechanism. The provided ones are the mainstream and widely used.

However, since the automatic transmission of this type switches the transmission ratio while continuing the transmission of torque, it is necessary to interpose a torque converter in a part of the transmission system path, which is not sufficient in terms of efficiency. For this reason, a lock-up clutch that can be directly connected to the torque converter is provided, and the lock-up clutch is operated to improve efficiency, for example, during high-speed traveling, but the mechanism becomes complicated. The adverse effects such as increase in weight and weight are unavoidable.

By the way, the complex clutch multi-stage automatic transmission installed in some sports cars etc. has a simple mechanism,
Therefore, since it has excellent features such as light weight and high transmission efficiency, it is desired to be mounted on a general automobile.

(Prior Art) As a conventional compound clutch type multi-stage automatic transmission, for example, there is one disclosed in Japanese Patent Laid-Open No. 58-118356. This automatic transmission has a pair of input shafts that can be connected to an engine output shaft via a dedicated clutch, and the pair of input shafts and an output shaft that is connected to a drive system via a final gear. A gear train having a selectable gear ratio is provided therebetween. When changing the gear ratio, one of the clutches is turned on and the other clutch is turned off at a predetermined timing, so that the input shaft connected to the engine output shaft is replaced to change the gear ratio. It is carried out.

According to such an automatic transmission, since the torque converter and the planetary gear are not required as described above, the automatic transmission has features that the mechanism is simple, lightweight and highly efficient.

However, in this type of automatic transmission, the only sliding element in the power transmission path is the clutch, and these clutches are dry or wet type clutches with frictional engagement in terms of efficiency. Therefore, there is a drawback in that the shift shock caused by the torque fluctuation during the shift transition when the input shafts are replaced is relatively large. Therefore, although it can withstand the use of special sports cars that place importance on efficiency, large shift shocks pose a serious problem and hinder the installation of general vehicles where driving feeling and other factors are important factors. It was In order to solve such an obstacle, the conventional method has proposed the following method.

That is, (I) during the gear shifting operation, the clutch on the non-power transmission side is engaged, and after a predetermined time has elapsed from the start of the gear shifting operation,
By disengaging the clutch on the power transmission side up to the present and setting the above specified time appropriately, smoothing the on / off timing of the pair of clutches, or (II) When the clutch on the transmission side is disengaged, the clutch on the non-power transmission side is already half-engaged, and if a load is applied to the engine via this half-engaged clutch, the engine speed will decrease. With this in mind, a method has been adopted in which the clutch that was on the power transmission side up to now is promptly disengaged when the engine speed decreases, and the clutch is smoothly switched to reduce shift shock.

(Problems to be Solved by the Invention) However, in the conventional method (I), when the engagement characteristic of the clutch is changed, it cannot be dealt with, and it is stable for a long period of time. However, there is a problem in that the shift shock cannot be reduced. Also (II)
In the above method, the change in the engine speed appears after the torque fluctuation is caused in the drive system, and at this time, the shift shock has already occurred. However, there is a problem in that only the shift shock after the decrease of the shift shock can be reduced, and a sufficiently satisfactory shift shock reduction effect cannot be obtained in terms of driving feeling.

(Object of the Invention) The present invention has been made in view of the above problems, and the clutch switching timing is set based on the actual change in the output shaft torque, so that the clutch switching can be performed at an appropriate torque. Perform smoothly under the share ratio,
The purpose is to reduce shift shock and improve driving feeling.

(Means for Solving the Problems) In order to achieve the above object, an automatic transmission according to the present invention includes a plurality of input shafts, a plurality of clutches for connecting each of the input shafts to an engine output shaft, and A speed change mechanism including one or more sets of speed change gears for drivingly connecting each of the input shafts to the output shaft, and a predetermined speed ratio capable of achieving a speed change ratio different from the current speed when a switch command to a speed change ratio different from the current speed is issued. A set of transmission gears is meshed and prepared, and a clutch on the side of the transmission gears of the predetermined set is engaged and disengaged, and a clutch currently engaged is disengaged in accordance with an operation signal, so that the input connected to the engine output shaft. In an automatic transmission that switches shafts and switches a gear ratio, a torque detection unit that detects a torque of the input shaft transmitted from an engine output shaft via the clutch that is operated to be turned off; Signal output means for outputting an operation signal for disengaging the clutch when the torque of the input shaft detected by the torque detecting means reaches a small torque value.

(Operation) In the present invention, the torque transmitted through the above-mentioned clutch on the power transmission side is detected during a gear shift operation in which a clutch other than the clutch on the power transmission side is engaged, and this torque is a small torque value. The clutch on the power transmission side is disengaged at the point when the power reaches.

That is, when the engagement pressure of this clutch gradually increases due to the operation of engaging the other clutch, the torque sharing shifts from the clutch on the power transmission side to the other clutch, and the transmission torque of the clutch on the power transmission side is almost zero. When the torque value becomes close to, the torque share of other clutches becomes almost 100%.

Therefore, this time point is the optimum timing for disengaging the clutch on the power transmission side, and since the disengagement operation is performed at this timing in the present invention, the clutch can be switched smoothly, and the actual torque Since the timing is set based on the variation, the smooth switching can be stably maintained for a long time regardless of the characteristic change of the clutch and the like.

(Example) Hereinafter, the present invention will be described with reference to the drawings.

1 to 5 are views showing an embodiment of an automatic transmission according to the present invention.

First, the configuration will be described. In FIG. 1, reference numeral 1 is an automatic transmission, and the automatic transmission 1 has a compound clutch multi-stage transmission 2 and a shift control device 3.

The compound clutch type multi-stage transmission 2 is provided with a first torque sensor 4 and a second torque sensor 5.
A specific configuration of the compound clutch type multi-stage transmission 2 including the torque sensor 4 and the second torque sensor 5 of FIG.

In FIG. 2, the compound clutch type multi-stage transmission 2 has an engine output shaft 6 that rotates by receiving a driving force (input torque Ti) from an engine (not shown) provided on the left end side in the figure.
A first clutch 7 and a second clutch 8 respectively provided at both ends of the engine output shaft 6, and a first input shaft 9 which can be connected to the engine output shaft 6 by connection of the first clutch 7. , Arranged on the same axis as the first input shaft 9,
A second input shaft 10, which may be connected to the engine output shaft 6 by the connection of the second clutch 8, a first input shaft 9 and a second input shaft 10.
A first output shaft 11 and a second output shaft 12 arranged in parallel with the input shaft 10, and the first input shaft 9, the second input shaft 10 and the first output shaft 10.
The output shaft 11 and the gear shift mechanism 13 provided on the second output shaft 12 are included.

The first clutch 7 has a flywheel 7a that rotates integrally with the engine output shaft 6, a pressure plate 7b and a diaphragm spring 7c, and a clutch disc 7d that is spline-fitted with the first input shaft 9. The clutch disc 7d is frictionally engaged between the flywheel 7a and the pressure plate 7b by the operating force F _A applied from the first clutch operating mechanism 14, and the engine output shaft 6 and the first input shaft 9 are connected. The first clutch operating mechanism 14 generates the operating force F _A when the first clutch engagement signal S _A input from the shift control device 3 described later is at “H” level.

The second clutch 8 rotates integrally with the engaged side member 8a that rotates integrally with the engine output shaft 6 and the second input shaft 10, and receives an operating force F _B such as hydraulic pressure. Works,
The friction member 8b that engages with the engaged side member 8a, and the second input shaft 10 by the engagement of the friction member 8b and the engaged side member 8a.
Is connected to the engine output shaft 6. The operating force F _B is the second
Is generated by the clutch operating mechanism 15 of the clutch operating mechanism 15
Generates the operating force F _B when the second clutch engagement signal S _B input from the shift control device 3 described later is at “H” level.

The gear speed change mechanism 13 includes four fixed gears, six speed change gears, and four sleeves. That is, the four fixed gears are composed of fixed gears 9a, 9b integrally formed on the first input shaft 9 and fixed gears 10a, 10b integrally formed on the second input shaft 10, and The six speed change gears are attached to the first output shaft 11, and are allowed to move in the circumferential direction of the first output shaft 11 such as a fifth speed gear 11a, a sixth speed gear 11b, and a second output shaft 12 1st speed gear 12a, 2nd speed gear 12b, 3rd speed gear 12 which are attached to the second output shaft 12 and are allowed to move in the circumferential direction of the second output shaft 12.
c, a fourth speed gear 12d, and further, four sleeves are attached to the first output shaft 11, and a reverse ← → fifth speed sleeve in which only the axial movement of the first output shaft 11 is allowed. 16 and 6 speed sleeves
17 and the second output shaft 12 attached to the second
Of the output shaft 12 is allowed to move only in the axial direction.

The four sleeves are driven by a drive mechanism (not shown), respectively, move in the directions of arrows (a) to (d), engage with the gear splines of the transmission gear in the moving direction, and the transmission gear and the first output shaft. 11 or the second output shaft 12 is connected.
For example, when the reverse ← → 5-speed sleeve 16 moves in the direction (a) and the gear spline 16 ′ of the reverse ← → 5-speed sleeve 16 and the gear spline 11 a ′ of the 5-speed gear 11 a engage with each other, this 5
The high speed gear 11a is connected to the first output shaft 11, and the engine output 6 and the first output shaft 11 are drive-connected via the fixed gear 9b in meshing relation with the fifth speed gear 11a. When the reverse ← → fifth speed sleeve 16 moves leftward in the drawing, it meshes with a reverse idler gear (not shown), and the reverse idler gear meshes with the fixed gear 9a of the first input shaft 9. Have a relationship. Therefore, in this case, the rotation of the first input shaft 9 is reversed and transmitted to the first output shaft 11, and the drive connection is performed in the backward direction.

Output gears 11d and 12e are integrally formed on the first output shaft 11 and the second output shaft 12, respectively, and these output gears 11d and 12e mesh with a common final drive gear (not shown). Then, the output shaft torque T ₀ transmitted to the first output shaft 11 or the second output shaft 12 is transmitted to the final drive gear.

In the compound clutch type multi-stage transmission 2 having such a configuration,
As described above, the first torque sensor 4 and the second torque sensor 5 are provided, and the specific configurations and functions of the first torque sensor 4 and the second torque sensor 5 are shown below. That is, the first torque sensor 4 is attached to the transmission case 20, and the first input shaft 9 and the pair of exciting coils 4a and 4a 'provided with a minute gap from the outer peripheral surface of the first input shaft 9 are provided. The second torque sensor 5 is attached to the transmission case 20 and also has a second input shaft. A pair of exciting coils 5a, 5 provided with a minute gap from the outer peripheral surface of 10.
a ', and a pair of groove bands 10c, 10c' formed of a large number of grooves formed on the outer peripheral surface of the second input shaft 10. That is, the first torque sensor 4 and the second torque sensor 5 have substantially the same configuration. Although the following description will be described with the first torque sensor 4 as a representative, it goes without saying that the second torque sensor 5 is also applied.

The direction of the grooves forming the pair of groove bands 9c, 9c 'forms a predetermined angle with respect to the central axis of the first input shaft 9, and the groove direction is symmetrical between the pair of groove bands 9c, 9c'. It has a shape. In such a torque sensor 4, when a slight torsional deformation occurs in the first input shaft 9 due to a change in shaft torque,
In the pair of groove bands 9c and 9c ', the angle formed by the direction of each groove and the central axis relatively changes such that one increases and the other decreases, and by this change, the angle with the central axis is changed. The magnetic permeability on the one groove band side which is increasing is increased, and the magnetic permeability on the other groove band side which is decreasing the angle with the central axis is decreased. Therefore, for each of the pair of groove bands 9c, 9c ', the exciting coil 4a,
When a magnetic flux is supplied from each of 4a ′, a current difference occurs in the exciting currents flowing through the exciting coils 4a and 4a ′ according to the change in the magnetic permeability, and this current difference is proportional to the magnitude of the torsional deformation of the first input shaft 9. Therefore, the input shaft torque T _A acting on the first input shaft 9 can be detected from the current difference.
Similarly, the second torque sensor 5 can detect the input shaft torque T _B acting on the second input shaft 10. That is, the first torque sensor 4 and the second torque sensor 5
Of the first clutch 7 and the second clutch 8,
When one of the two is turned off, the engine output shaft 6
It has a function as a torque detecting means for detecting the input shaft torque T _A or the input shaft torque T _B transmitted through the clutch that is disengaged from the clutch.

Again, in FIG. 1, the shift control device 3 has a function as a signal output means, and is configured to include a torque ratio calculation unit 3a, a timing setting unit 3b, and a shift operation control unit 3c. Each of these units 3a to 3c is configured by a microcomputer or the like that is independent of each unit or common to each unit, and executes various necessary processes according to a predetermined program. That is, the torque ratio calculation unit 3a calculates these torque ratios T _R based on the input shaft torque T _A and the input shaft torque T _B detected by the first torque sensor 4 and the second torque sensor 5. . The timing setting portion 3b, a torque ratio T _R and the transmission destination is input from the shift operation control unit 3c gear ratio Ri
(However, i = 1 to 6th speed or any one of reverse speed) and the like are used to determine the disengagement timing of the disengagement side clutch during the transition of the shift. Specifically, when one of the first clutch 7 and the second clutch 8 changes to engagement,
When the decrease in the transmission torque of the other clutch due to this engagement substantially matches a predetermined reference value (for example, a value corresponding to zero torque), an operation signal TM prompting the disengagement of the other clutch.
Output G.

The shift operation control unit 3c finely sets the optimum shift point for the running state of the vehicle based on various information indicating the running state of the vehicle such as the throttle opening and the vehicle speed (not shown), and issues a shift command as necessary to the compound clutch. Output to the multi-stage transmission 2. Here, the shift command is a command signal for moving the four sleeves of the compound clutch type multi-stage transmission 2 or a first clutch engagement signal for engaging the first clutch 7 and the second clutch 8. S _A , second clutch engagement signal S _B
Etc. are included.

 Next, the operation will be described.

When the selected gear ratio is, for example, the third speed, the torque transmission is as follows: engine → engine output shaft 6 → engaged first clutch shaft 7 → first input shaft 9 → fixed gear 9b →
Third speed gear 12c → sleeve 18 → second output shaft 12 → output gear 1
2e → Transmitted to final drive gear, 3rd gear 12
The torque is increased in accordance with the gear ratio of c and the fixed gear 9b (in this case, the third gear ratio; hereinafter R ₃ ) and To = Ti
× R ₃ is transmitted to the drive system via the final drive gear.

On the other hand, torque transmission in the case of the fourth speed is as follows: engine → engine output shaft 6 → second clutch 8 → first output shaft 10 → fixed gear 10a → fourth speed gear 12d → second output shaft 12 → output gear 12e
→ Fixed gear 10a transmitted to the final drive gear
And an increase in torque according to the gear ratio of the 4th gear 12d (in this case, the 4th gear ratio, hereinafter R ₄ ) (however, R ₄ = 1,000
If so, there is no increase action), and To = Ti × R ₄ is transmitted to the drive system via the final drive gear.

Further, in the speed change operation from the third speed to the fourth speed, first, at the time of the third speed, the engagement of the second clutch 8 on the power non-transmission side is started to gradually increase the engagement pressure, and the predetermined timing is reached. Then, the first clutch 7 on the power transmission side is disengaged to switch to the fourth speed torque transmission system path. If this timing is not appropriate, idling of the engine will occur and a large amount of torque will be pulled in due to the interlock (that is, shift shock), which is not desirable.

Therefore, in this embodiment, the shaft torques of the first input shaft 9 and the second input shaft 10 (that is, the input shaft torques T _A and T _B ) are detected, and, for example, in the 3rd speed → 4th speed upshift,
When the input shaft torque T _A of the first input shaft 9 decreases to a predetermined minute value, it is assumed that the sharing torque of the first clutch 7 on the side of the first input shaft 9 becomes almost zero, and this timing Therefore, the first clutch 7 is disengaged. Therefore, at this time point, the second clutch 8 to which the gear shift is applied is almost
Since the torque is shared by 100%, the shift from the 3rd speed to the 4th speed is smoothly performed, and the shift shock can be reduced. Moreover, even if the engagement characteristics of the first clutch 7 and the second clutch 8 change, this can be dealt with, and the above smoothness can be maintained for a long period of time.

The operation of the present embodiment will be described below with reference to the timing charts of FIGS.

In FIG. 3, before the time t ₀ when the shift is started, the first clutch engagement signal S _A is output at the “H” level, the first clutch 7 is engaged, and the above-mentioned 3 A transmission line at high speed is formed.

When the shift from the third speed to the fourth speed is decided at time t ₀ , the second clutch engagement signal S _B changes to “H” level,
The operation force F _B is generated by the second clutch operation mechanism 15, and the second clutch 8 keeps backlash. While this backlash is being reduced (that is, between time t _{0 and} t ₁ ), the gear ratio remains at the 3rd speed and the output shaft torque To
The torque generated by increasing the input torque Ti at that time by the gear ratio R ₃ of the third speed is generated.

When the backlash of the second clutch 8 becomes zero at time t ₁ , the second clutch 8 starts the engaging operation. Then, with the growing engagement pressure, while the transmission torque TC _B of the second clutch 8 is increased, the first clutch 7
The transmission torque TC _{A of} is decreasing. Thus, we began to decrease in response to a decrease in the output shaft torque To is also TC _A.

At time t ₂ , when the output shaft torque To decreases to a value corresponding to the product of the input torque Ti and the gear ratio R ₄ of the fourth speed, TC _A
While sharing torque becomes substantially zero, and reaches the next approximately 100% allotted torque of TC _B, the second clutch 8 almost all the Ti of the time R ₄ times the To is sharing. Therefore, in this case, a decrease in the output shaft torque To can be detected from the input shaft torque T _A of the first input shaft 9 that was on the power transmission side at the third speed, and To = Ti × Ri (however, It is possible to know that Ri = the gear ratio of the gear change destination) has been reached. Further, by detecting the ratio of the input shaft torque T _A and the input shaft torque T _B , the torque sharing ratio of the first clutch 7 and the second clutch 8 can be known, and thus the above To
= You can know that you have reached Ti x Ri.

In this way, when the torque sharing of the first clutch 7 on the power transmission side at the 3rd speed is detected to be substantially zero, the operation signal TMG is promptly output, whereby the shift operation control unit 3
c changes the first clutch engagement signal S _A to the “L” level and outputs the first clutch 7 to the first clutch operating mechanism 14. As a result, the operating force F _A from the first clutch operating mechanism 14 is turned off and the first clutch 7 is disengaged,
The torque capacity MTC _A of the clutch 7 becomes zero.

During the time period from t _{2 to} t ₃ , Ni is lowered by the margin α of the torque capacity MTC _B of the second clutch 8 and the amount of work required for the reduction is released as the inertia torque INT.
That acts as a so-called inertia phase during the time t ₂ -t _3, the meantime, INT is added to To, temporarily rises to _{To = Ti × R 4 + INT} .

At time t ₃ , when INT is completely released, TC _B becomes 4
The speed becomes a value corresponding to the assigned torque, and To also becomes a value of Ti × R ₄ along with this, and the speed change operation ends.

Thus, in this embodiment, the first input shaft 9 and the second input shaft 9
Of the input shaft 10, that is, the input shaft torques T _A and T _B , and based on the detected values, whichever of the first clutch 7 and the second clutch 8 was on the power transmission side before the gear shift. One of the points where the torque sharing is zero is detected, and this point is set as the disengagement timing of the clutch. Therefore, since the timing is set based on the actual transmission torque value, stable and smooth clutch replacement can be performed without being affected by changes in the engagement characteristics of the clutch,
The shift shock can be effectively reduced.

That is, as shown in FIG. 4, for example, assuming that the disengagement timing of the first clutch 7 is delayed by x hours and disengagement is performed at time [t ₂ + x], the first clutch 7 and the Both clutches 8 of 2 are at time x
Since both are in the engaged state, in this case, an interlock is generated, a torque is pulled in, and a large shift shock is caused. Further, as shown in FIG. 5, the disengagement timing of the first clutch 7 is changed. when it earlier by x times is assumed that was cut at time [t ₂ -x], while the transmission torque TC _B of the second clutch 8 is not increased sufficiently, the first clutch 7 is disconnected As a result, problems such as the occurrence of the engine idle phenomenon due to the respective timing deviations occur. However, according to the present embodiment, such problems can be avoided.

(Effect) According to the present invention, the clutch disengagement timing is set based on the actual change in the output shaft torque, so that the clutch can be switched smoothly under an appropriate torque sharing ratio. Therefore, the shift shock can be reduced and the driving feeling can be improved.

[Brief description of drawings]

1 to 5 are views showing an embodiment of an automatic transmission according to the present invention, FIG. 1 is an overall configuration diagram thereof, and FIG. 2 is a specific configuration of the compound clutch type multi-stage transmission 2. Showing the figure,
FIG. 3 is a timing chart for explaining the operation, and FIGS. 4 and 5 are timing charts showing an example of timing failure for explaining the effect. 3 ... Shift control device (signal output means), 4 ... First torque sensor (torque detection means), 5 ... Second torque sensor (torque detection means), 6 ... Engine output shaft, 7 ...
... first clutch (plural clutches), 8 ... second clutch (plural clutches), 9 ... first input shaft (plural input shafts), 10 ... second input shaft (plural input shafts) ),13……
Gear shift mechanism (shift mechanism).

Claims (1)

[Claims] 1. A plurality of input shafts, a plurality of clutches for connecting each of the input shafts to an engine output shaft, and one or more sets of speed change gears for drivingly connecting each of the input shafts to an output shaft. When a command to switch to a gear ratio different from the present is provided, a gear set of a predetermined set capable of achieving a gear ratio different from the present is meshed and prepared. In the automatic transmission that switches the clutch on and off, the clutch currently engaged according to the operation signal is switched, the input shaft connected to the engine output shaft is switched, and the gear ratio is switched. Torque detecting means for detecting the torque of the input shaft transmitted from the engine output shaft via a clutch, and when the torque of the input shaft detected by the torque detecting means reaches a minute torque value. And a signal output means for outputting an operation signal for disengaging the clutch.