JPH01182660A - Automatic transmission - Google Patents

Abstract

PURPOSE:To release output torque at optimum timing when sharing torque comes to zero as well as to abate a shift shock by detecting the actual output torque of both input and output shafts, and setting the release timing of a release factor from the variation. CONSTITUTION:Input shaft torque Tt is calculated at a computing element 33 with rotational frequency of an engine 1 being detected by a speed sensor 2, and input shaft rotating speed of a transmission 5 via a torque converter 4 being detected by a speed sensor 6. Then, it is inputted into a release timing setter 34 together with output shaft torque To out of a torque sensor 8, and intershaft torque TR' is calculated at an operational part 34a. In addition, a timing setting part 34b outputs a release timing signal TMG at a shift point where desired output shaft torque of TtXRi and actual torque To are accorded with each other on the basis of this TR' at shift transition and a shift ratio Ri at the shift destination, and shift signal SA, SB are outputted from a shift controller 35. Thus, release takes place at optimum timing when a sharing torque of a release factor is zero, and thus a shift shock is abatable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an automatic transmission device for a vehicle, etc., and particularly to an automatic transmission device intended to reduce shift shock.

(Prior Art) Generally, in an automatic transmission having multiple gear stages, the gear shifting operation is performed while power from the engine is being transmitted to the drive system, and the gear ratio is changed in stages. The torque fluctuations in the drive system caused by this change in acceleration cause the vehicle body to experience a considerable amount of so-called gear shift shock.

Such a shift shock is undesirable because it worsens the driving feeling, and it is desirable to reduce it as much as possible.

FIG. 5.6 is a diagram showing the torque flows of the second and third speeds of a typical automatic transmission.

In addition, the solid line in the figure indicates torque transmission 6. : Indicates the yarn path involved, and the dotted line represents the yarn path that is not involved. Further, black circles indicate friction elements in a fastened state, and white circles indicate friction elements in a released state.

In FIG. 5, second-speed torque is transmitted via a thread path from an input shaft 100 through a rear planetary gear 101 to an output shaft 102. Further, the reaction torque Tx from the band brake 103 in the engaged state is transmitted from the front planetary gear 104 to the forward clutch 105 to the forward one-way clutch 106 to the rear planetary gear 101 to the output shaft 102. Therefore, the input torque Ti from the engine is applied to the output shaft 102.
T out (Tout
= T x + T in) appears, and the torque is increased in accordance with the gear ratio of the second speed.

In FIG. 6, the third speed torque is transmitted by a thread path from the input shaft 100 through the rear planetary gear 101 to the output shaft 102, and from the input shaft 100 to the high clutch 107 in the engaged state to the front planetary gear. - Gear 104 → Forward clutch 105 → Forward one-way clutch 106 → Rear planetary gear 101 →
The signal is transmitted through two thread paths via a path leading to the output shaft 102 as well. That is, the input torque Tin from the engine
is transmitted through the above two thread paths, so the output shaft 1
The torque Tout transmitted to the 02 is the sum of 1-luk T a s T b shared by the two yarn paths. For example, if the gear ratio of 3rd speed is 1,000, the
n=Ta+Tb, and the input torques Tin and Tout match.

Switching the powertrain like this (2nd speed - 3rd speed)
In this case, the high clutch 107 is changed to the engaged state while the band brake 103, which is in the engaged state in 2nd gear, is released, and the torque flow is switched as shown in Fig. 5.6 above. clutch 1
Depending on the release and engagement timing of 07, the torque flow may not be smoothly switched and a large shift shock may occur.

An example of a conventional automatic transmission device of this type that reduces shift shock is disclosed in Japanese Patent Application Laid-open No. 31746/1983. In this device, the release timing of one friction element (hereinafter referred to as release side element) that changes from the engaged state to the released state during gear shifting is set as follows. In other words, the other friction element (hereinafter referred to as the engagement side element), which changes inversely from the released state to the engagement state in cooperation with the operation of the one friction element described above, enters a semi-connected state, and through this engagement side element, A certain time tx is determined in advance until a slight load starts to be applied to the engine, and the release timing is set when this time tx has elapsed.

(Problem to be Solved by the Invention) However, in such a conventional method, the release timing of the release side element is set to a single fixed time tX, and therefore If the characteristics of the torque converter and friction elements of the machine change, a deviation may occur between the actually required optimal release timing (hereinafter referred to as the "actual timing"). For example, if the actual timing is delayed, The releasing element is released before the transmission torque of the engaging element has increased sufficiently, and in this case, engine racing occurs.

In addition, if the actual timing is advanced, even after the transmission torque of the engagement side element has increased sufficiently, the engagement state of the release side element will continue, and in this case, an interlock will occur and a large retraction will occur. There were problems such as the generation of torque, which caused the user to experience an unpleasant shift shock.

(Object of the invention) The present invention was made in view of the above problems, and
By detecting the actual shaft torque of the input shaft and output shaft and setting the release timing based on changes in this shaft torque, it is possible to match the actual timing with the release timing, and prevent changes in engine operating conditions and automatic transmissions. The aim is to reduce shift shock regardless of changes in the characteristics of the gearbox.

(Means for Solving the Problems) In order to achieve the above object, an automatic transmission according to the present invention includes an input shaft rotationally driven by an engine, an output shaft coupled to a drive system, and an input shaft and an output shaft connected to each other. A gear transmission mechanism that is interposed between the gears and can select one of a plurality of speed ratios, and a friction engagement mechanism that selectively engages and releases a plurality of friction elements to select the speed ratio, When a speed change command for switching to a predetermined speed ratio is input, one of the at least two friction elements of the friction engagement mechanism is engaged while one of the friction elements is transitioning from a released state to an engaged state. In an automatic transmission device, the other friction element in a state is brought into a released state in accordance with a predetermined timing signal, and a gear ratio between the input shaft and the output shaft is switched to a predetermined gear ratio, and a shaft torque of the input shaft is detected. an input shaft torque detection means, an output shaft torque detection means for detecting the shaft torque of the output shaft, and an output shaft torque detection means for detecting the shaft torque of the output shaft; The apparatus includes a calculating means for calculating a target output shaft torque, and a signal generating means for generating the predetermined timing signal when the detected output shaft torque reaches the target output shaft torque.

(Function) In the present invention, when a gear change command for switching to a predetermined gear ratio is input, a target output shaft torque is calculated based on the input shaft torque and a predetermined gear ratio, and the target output shaft torque is adjusted to the target output shaft torque. When the actual output shaft torque is reached, the release side element is released.

Here, the output shaft torque after the shift is completed is a torque conversion of the input shaft torque according to the gear ratio of the gear selected by the engaging side element, and at this time, the disengaging side element is in a completely released state. . Therefore, when the actual output shaft torque and the target output shaft torque almost match, the engagement-side element shares approximately 100% of the torque, while the disengagement-side element shares approximately 0% of the torque.
%. In other words, when this coincidence occurs, it is the optimum actual timing to release the release side element, so as in the present invention, by setting the release timing based on the actual input shaft torque, output shaft torque, etc., the actual timing can be adjusted. The timing and release timing can be matched, regardless of engine operating conditions or changes in automatic transmission characteristics.
Shift shock can be reduced.

(Example) Hereinafter, the present invention will be explained based on the drawings.

1 to 4 are diagrams showing an embodiment of an automatic transmission according to the present invention, and are an example applied to an electronically controlled automatic transmission with four forward speeds and one reverse speed.

First, the configuration will be explained. In FIG. 1, reference numeral 1 denotes an engine. The engine 1 generates a driving force according to the operation amount of a throttle pedal (not shown), and uses this driving force to rotationally drive a crankshaft (not shown). Further, the rotation speed of the crankshaft of the engine 1, that is, the engine rotation speed Ne is detected by the engine rotation sensor 2.

Reference numeral 3 denotes an automatic transmission, and the automatic transmission 3 includes a torque converter 4 and a transmission 5. The transmission 5 includes an input shaft rotation sensor 6 and an output shaft 7 that detect the rotation speed Nt of an input shaft 10, which will be described later. Torque sensor (to detect the shaft torque (output shaft torque To) of
Output shaft torque detection means) 8 is provided.

The automatic gear shift m3 is shown in detail in FIG. 2.

In FIG. 2, the torque converter 4 includes a pump impeller 9 connected to the engine crankshaft and rotating integrally with the shaft, and an input shaft 1 of the transmission 5.
The turbine impeller 11 is spline-fitted to the converter housing case 12, and the stator 13 is integrally fixed to the converter housing case 12. When the pump impeller 9 is rotationally driven by the driving force of the engine, the internal The driving force of the engine is transferred from the turbine impeller 11 to the input shaft 10 through the fluid of
to communicate.

The transmission 5 has the above-mentioned input shaft 10 and an output shaft 7 connected to a drive system including a supinated drive shaft, a final gear, a drive wheel, etc., and between the input shaft 10 and the output shaft 7. A gear transmission mechanism 15 is interposed therein. The gear transmission mechanism 15 has, for example, two sets of planetary gears, namely a front planetary gear 16 and a rear planetary gear 17, and each planetary gear is provided at the center, as is already known. sun gear 16a
, 17a, a plurality of pinion gears 16b, 17b meshing with the sun gear, planet carriers 16c, 17c supporting the pinion gears, and planet carrier 16.
Ring gear 16 provided on the outer periphery in mesh with c117c
d and 17d, and by fixing one of the three, the sun gear, planet carrier, and ring gear, and connecting the other two to the drive side and the driven side, transmission from the drive side to the driven side is achieved. The rotational torque applied can be decreased or increased in multiple stages.

In addition, the degree of reduction or increase is determined by the gear ratio determined from the number of teeth of the sun gear and ring gear, the number of rotations of the sun gear, etc. If any of the three is selectively fixed, one of the multiple gear ratios will be selected. Ru. Incidentally, the gear ratios in this embodiment are 2.785 for 1st gear (hereinafter referred to as R1), 1.545 for 2nd gear (hereinafter referred to as R2), 1.000 for 3rd gear (hereinafter referred to as R1), 4th gear is 0.694
(hereinafter referred to as R4), the retreat is 2.272 (hereinafter referred to as Rl
I).

Selection of the gear ratio is performed by the frictional engagement mechanism 18, and the frictional engagement mechanism 18 includes a plurality of frictional elements.

The friction elements include, for example, a band brake 19, a reverse clutch 20, a high clutch 21, a forward clutch 22, an overrun clutch 23, a forward one-way clutch 24, a row one-way clutch 25, and a ROHM reverse brake 26, depending on the supplied hydraulic pressure. Selectively engage and release the front planetary gear 1.
6 and the fixed portions of the rear planetary gear 17 are switched to achieve one of the plurality of speed ratios described above.

Here, the above-mentioned plurality of friction elements are arranged such that during a shift transition, one friction element moves from disengagement to engagement while the other friction element operates relatively from engagement to disengagement. It contains a pair of frictional elements in the relationship. For example, in the case of the present embodiment, this is the relationship between the high clutch (the negative friction element) 21 and the band brake (the other friction element) 19 during the 2nd and 3rd speeds, and the high clutch 21 is engaged. During this transition, the band brake 19 is released at an appropriate timing. If this release timing is inappropriate, it is not preferable because, as described above, the engine may run dry or an interlock may occur, causing the user to experience a shift shock.

In this embodiment, as will be described in detail later, this release timing is always set optimally to prevent the engine from revving or interlocking.

Note that the above-mentioned Fj friction engagement mechanism 18 is connected to the hydraulic control mechanism 2.
A plurality of friction elements are selectively engaged or released by the hydraulic pressure supplied from 7, and the hydraulic control mechanism 27 switches the hydraulic path to each friction element in accordance with a shift command signal from a shift control device 35, which will be described later.

Note that sA, 311 in FIG. 2 indicates a part of the shift command signal, and when SA changes from "H" to "L",
When the band brake 19 changes from engagement to release and S changes from 1L to H, the high clutch 21 changes from release to engagement.

An input shaft rotation sensor 6 is fixed to the transmission case 28, and the input shaft rotation sensor 6 is disposed with a predetermined gap from the outer peripheral surface of the input shaft 10. The input shaft 10 has irregularities such as serrations formed on its outer peripheral surface, and the input shaft rotation sensor 6 detects the movement of the irregularities as the input shaft 10 rotates as a change in magnetic flux, and uses this change in magnetic flux as an electrical signal. The number of rotations Nt of the input shaft 10 is detected by converting it into .

Further, a torque sensor 8 is fixed to the rear extension 29, and a known magnetostrictive torque sensor, for example, is used as the torque sensor 8. That is,
The torque sensor 8 includes a pair of excitation coils 30 and 30' provided with a gap along the circumferential direction of the outer peripheral surface of the output shaft 7.
and a pair of groove bands 31, 31' consisting of a large number of grooves formed on the outer peripheral surface of the output shaft 7, and a pair of groove bands 31.3.
The direction of the grooves constituting 1' forms a predetermined angle with respect to the central axis of the output shaft 7, and the groove directions are symmetrical between the pair of groove bands 31 and 31'. In such a torque sensor 8, when a slight torsional deformation occurs in the output shaft 7 due to a change in shaft torque, the pair of groove bands 31 and 31'
The angle between the direction of each groove and the central axis changes relatively so that one increases and the other decreases, and due to this change, the angle between the groove and the central axis increases. The magnetic permeability increases, and the magnetic permeability on the other groove side, which reduces the angle with the central axis, decreases. Therefore, the pair of grooves 31.3
When magnetic flux is supplied from each of the excitation coils 30 and 30' to each of the excitation coils 30 and 30', a current difference occurs in the excitation current flowing through the excitation coils 30 and 30' according to the change in magnetic permeability, and this current difference is caused by the output shaft 7. Since it is proportional to the magnitude of torsional deformation, the output shaft torque TO can be detected from the current difference.

Again, in FIG. 1, 33 is an input shaft torque calculation device, and the input shaft torque calculation device 33 is composed of, for example, a microcomputer, and stores data and information corresponding to the torque capacity coefficient CF shown in the characteristic diagram of FIG. Data corresponding to the torque ratio TR before and after the torque converter is stored in the internal memory as a table map. The input shaft torque calculation device 33 executes the following processing according to a predetermined program.

That is, the speed ratio e before and after the torque converter 4 is determined according to the following equation (2), and the values of CF and TR corresponding to the determined speed ratio e are looked up from the table map.

Next, the input torque Ti of the torque converter is calculated according to the following formula (■), and Ti=CFXn,''...-■ However, the CF nil picked up value and the shaft torque of the input shaft 10, i.e., according to the following formula (■). Calculate the input shaft torque Tt.

Tt=TiXe...■ Therefore, the input shaft torque calculation device 33, the engine rotation sensor 2, and the input shaft rotation sensor 6 constitute input shaft torque detection means.

34 is a release timing setting device as a calculating means and a signal generating means, and the release timing setting device 34 is
It is composed of a microcomputer or the like, and has a torque ratio calculation section 34a and a timing setting section 34b.

The torque ratio calculating section 34a calculates an inter-shaft torque ratio TR' including the current gear ratio between the input shaft 10 and the output shaft 7 according to the input shaft torque Tt and the output shaft torque TO. That is, the torque transmitted from the input shaft 10 to the output shaft 7 is increased or decreased by a predetermined ratio according to the gear ratio at that time. For example, in 2nd gear, the input shaft torque Tt is
z ”=1.543) becomes the output shaft torque TO, and when in 3rd gear, Tt is multiplied by R3 (R3=1.0
00) The multiplied value becomes TO. Therefore, after switching to a predetermined gear ratio, TR' has a value that matches the value of the gear ratio at that time. (speed), TR' changes from a value corresponding to R2 to a value corresponding to R1, and when R3 and TR' match, it is the so-called conversion point from the torque phase to the inertia phase. That is, at this conversion point, the torque share of the release side element (for example, band brake 19) is
Since it becomes "0", the release timing can be determined by detecting this conversion point.

From this point of view, the timing setting section 34b
In addition to monitoring TO, the calculated T during shift transition is
Based on R' and Ri of the shift light (where i = 1.2.3 or R), find the conversion point where the target output shaft torque and the actual output shaft torque To match, where TtXRi = To. A release timing (predetermined timing signal) signal TMG is output at the time of detection.

Note that since the release element is operated by hydraulic pressure, there may be a slight response delay, so it may be corrected to accelerate the TMG output in anticipation of this response delay α, as shown in the following equation (■). .

7 't It may be corrected.

TtXRi+α'='["0 ・-,,, ■However, α
': The correction coefficient 35 is a speed change control device, and the speed change control device 35 is composed of a microcomputer, etc., and finely determines the optimal speed change point for the vehicle running condition based on various information such as throttle opening and vehicle speed. , outputs a shift command signal to the hydraulic control mechanism 27 of the transmission 5 as necessary. For example, when the running state of the vehicle reaches the upshift point from 2nd to 3rd speed, Sl
Shifting is started by changing l from "L" to "H" level, and when TMG is input from release timing setting device 34, SA is changed from "H" to "L" level. Note that the shift control device 35 outputs shift information including the gear ratio Ri of the shift destination to the release timing setting device 34.

Next, the operation will be explained with reference to a timing chart shown in FIG. 4 showing the timing of the shift operation from second speed to third speed.

First, at time t0, the running condition changes and 2nd gear - 3rd gear
When the upshift point to speed is reached, the speed change control device 35
changes Sll from the L" to "H" level and commands the start of the gear shift operation. The high clutch 21 starts operating from the disengaged state to the engaged direction according to S, gradually reducing backlash. I'm going. While I'm filling up this backlash (t.

-tl), the gear ratio remains at 2nd speed before switching, that is, the TO during that time shows the magnitude determined by '1"txR. Furthermore, during 10-1. In the case of a shift, the throttle pedal is normally depressed and both Ne and Nt tend to rise, but for the sake of explanation, it is assumed that these are constant, and it is also assumed that the rotation speed of the output shaft 7 does not change. , are shown so that only the torque change due to the change in the gear ratio is shown.

Therefore, it should be recognized that this does not strictly correspond to the actual driving condition.

At time t, when the backlash of the high clutch 21 becomes "0" and engagement is started, the transmission torque T Cm of the high clutch 21 increases as the locking pressure increases, while the transmission torque T Cm of the band brake 19 increases. The transmission torque TCA decreases and enters a so-called torque phase. During this torque phase, TO changes in a decreasing direction as 'rca decreases.

At time t2, To decreases and reaches the point 'l'o=7'tXR3 indicated by the arrow in the figure, that is, Rs=1. Since OOO, in this case To=T
When it matches t, TC, satisfies the torque sharing in 3rd gear, while TCA has a torque sharing of "0". Therefore, T o −T to end this torque phase
At point t, TMG is output from release timing setting device 34, and transmission control device 35 receives TMG and sets SA to “H”.
-Change to “L”. As a result, band brake 1
9 is quickly released in accordance with the change in SA, and the torque capacity IMTCA of the band brake 19 becomes 0'' and is disconnected.

Time 1. -13, Nt is lowered by the torque margin A of the torque capacity IMTCs of the high clutch 21, and the amount of work required for the lowering is released as the inertia torque INT. That is, time 1. -1. During this period, INT acts as a so-called inertia phase, and during this period, INT is added to TO, and -temporally, To=TtXR.
The upper bound is up to i+INT.

At time t, when INT is completely released, TC
, is a value corresponding to the shared torque determined in 3rd gear,
Along with this, TO also becomes stable at the value of TtXR3, and the shift operation is completed.

In this embodiment, the input shaft torque Tt during the shift transition period is calculated based on the engine speed Ne, the input shaft speed Nt, the torque capacity coefficient CF of the torque converter 4, and the torque ratio TR before and after the torque converter. death,
A value (that is, target output shaft torque) is obtained by multiplying this Tt by R1 of the shift destination, and the time when the output shaft torque TO reaches this value is set as the release timing of the release side element. Therefore, since the release side element is released based on the change in the actual input shaft torque Tt, control accuracy is improved, and when the torque share of the release side element becomes "0", it is appropriately released. be able to. the result,
Engine racing and interlocks can be avoided, and shift shocks can be reduced regardless of engine operating conditions or changes in the characteristics of the automatic transmission.

(Effect) According to the present invention, the actual shaft torque of the input shaft and output shaft is detected, and the release timing of the release element is set based on the change in this shaft torque, so that the shared torque of the element is
The release timing can be adjusted to the optimum timing at which the transmission speed becomes 0°, and shift shock can be reduced regardless of changes in engine operating conditions or changes in characteristics of the automatic transmission.

[Brief explanation of the drawing]

1 to 4 show an embodiment of an automatic transmission according to the present invention, in which FIG. 1 shows the overall configuration thereof, FIG. 2 shows a specific configuration of the automatic transmission, and FIG. Figure 3 is a characteristic diagram showing various characteristics of the torque converter, Figure 4 is a timing chart to explain its operation, and Figures 5 and 6 are diagrams of D2 speed and D3 speed, respectively, to explain the problems of the conventional method. It is a figure showing the torque flow of. 7...Output shaft, 8...Torque sensor (output shaft torque detection means)
, 10... Input shaft, 15... Gear transmission mechanism, 18... Friction engagement mechanism, 19... Band brake (other friction element),
21...High clutch (one friction element), 3
4...Release timing setting device (calculating means, signal generating means). Applicant Nissan Motor Co., Ltd. Figure 3 Speed ratio e Figure 5 Figure 6

Claims (1)

[Scope of Claims] An input shaft rotationally driven by an engine, an output shaft coupled to a drive system, and an input shaft interposed between the input shaft and the output shaft,
A gear transmission mechanism that can select one of a plurality of transmission ratios, and a friction engagement mechanism that selects the transmission ratio by selectively engaging and disengaging a plurality of friction elements, the gear transmission mechanism being able to select the transmission ratio to a predetermined transmission ratio. When a shift command for switching is input, one of the at least two friction elements of the friction engagement mechanism shifts from the released state to the engaged state, while the other friction element, which is in the engaged state, shifts from the released state to the engaged state. In an automatic transmission device in which a friction element is brought into a released state according to a predetermined timing signal and a gear ratio between the input shaft and the output shaft is switched to a predetermined gear ratio, the input shaft torque detection means detects the shaft torque of the input shaft. and an output shaft torque detecting means for detecting the shaft torque of the output shaft, and a target output shaft torque detecting means for detecting the shaft torque of the output shaft, and a target output shaft torque when the gear ratio is switched to a predetermined gear ratio based on the detected input shaft torque and the predetermined gear ratio. An automatic transmission device comprising: calculation means for calculating; and signal generation means for generating the predetermined timing signal when the detected output shaft torque reaches the target output shaft torque.