JPH03229057A - Automatic transmission for vehicle - Google Patents

Abstract

PURPOSE:To improve the durability in a frictional engaging means as well as to make shift control so easy by making a speed change in a turning member, and performing an engaging motion of the specified frictional engaging means together with other frictional engaging means. CONSTITUTION:At time of starting the engagement of a second clutch means K2 for setting a fourth gear speed, a third brake means B3 is engaged to some extent and rotational frequency of an input shaft 4 is preliminarily lowered, so that an inertial energy value to be absorbed becomes lessened for a while till being completely engaged since the engagement of the second clutch means K2 has started. Since inertial energy with a variation in input shaft speed at time of shift is absorbed as shared by the third brake means B3 and the second clutch means K2 like that, load being imposed on the second clutch means K2 is sharply reduced in comparison with the case being directly shifted from the third gear speed to the fourth one. Therefore durability in the third brake means B3 and the second clutch means K2 can thus be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION This invention relates to an automatic transmission that is set to a plurality of gear stages in response to a combination of engagement and disengagement of a plurality of frictional engagement means.

Conventional technology A typical automatic transmission installed in a car etc. consists of a gear train mainly consisting of multiple sets of planetary gear mechanisms, and the connection state of the rotating members or the connection between the rotating members and the input shaft is difficult. It is configured to set a plurality of gears by changing the state and fixed state of rotating members using frictional engagement means such as clutches and brakes, and each gear basically depends on the engine speed represented by the throttle opening. It is set according to the load and vehicle speed. Shifting in this type of automatic transmission is performed by switching between the engaged and disengaged states of the frictional engagement means, which not only changes the output shaft torque but also changes the rotational members that make up the gear train. Causes fluctuations in rotation speed. If these fluctuations are sudden and large,
This is experienced as a shift shock, which reduces ride comfort.

Conventionally, therefore, the frictional engagement means is generally engaged slowly so that the inertial energy is absorbed by the sliding of the frictional engagement means, so that changes in the output shaft torque and the rotational speed of the rotating member are made smooth.

However, if the inertia energy that the frictional engagement means must absorb during gear shifting is large due to the large shaft rotational speed of an automatic transmission, the frictional engagement means will slip and the accompanying wear and deterioration will become severe. As a result, the durability of the frictional engagement means is impaired. In order to eliminate this inconvenience, it may be possible to increase the hydraulic pressure for engaging the frictional engagement means to reduce slippage, but in this case, the engagement timing becomes faster, causing a shift shock. This will lead to greater inconvenience.

Therefore, the present applicant has developed a system in which one of the frictional engagement means is gradually engaged to execute a shift, and at the same time, other frictional engagement means that are not involved in setting the target gear are engaged until just before the shift is completed. We have already proposed a control method to
No. 50052). According to this method, a part of the inertial energy that should be absorbed by the frictional engagement means engaged in order to set the target gear is absorbed by the other frictional engagement means. The load on the means is reduced, and its durability can be improved.

Problem to be Solved by the Invention However, in the above conventional method of dispersing the inertial energy to be absorbed during gear shifting into two frictional engagement means, in order to engage the two frictional engagement means simultaneously, If the timing of releasing one of the frictional engagement means, that is, the frictional engagement means that is not involved in setting the target gear, is not precisely controlled, the entire gear train may lock, or the gear train may become locked. There is a possibility that a situation may occur in which the target gear is returned to after being set to another gear beyond the target gear. In such cases, sudden fluctuations in output shaft torque may occur, and excessive temporary loads may be placed on any of the members, impairing their durability. Therefore, in order to prevent such inconveniences, , the above conventional method requires high precision and complicated speed change control;
There was room for improvement in this respect.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an automatic transmission that facilitates speed change control while dispersing the inertial energy to be absorbed into a plurality of frictional engagement means. .

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a system in which each rotating member of a gear train mainly consisting of a plurality of sets of planetary gear mechanisms is engaged and released by a plurality of frictional engagement means. In an automatic transmission for a vehicle that is set to a plurality of gears by connecting or fixing them to each other by a combination of
Prior to the frictional engagement means to be engaged when shifting to the second gear, another frictional engagement means to be released is temporarily engaged to set the second gear. A change in the rotational speed of a rotating member whose rotational speed changes with the shift from the first gear to the second gear is caused in advance, and the predetermined frictional engagement is performed together with the releasing operation of the other frictional engagement means. The present invention is characterized in that it includes a control device for causing the means to engage.

Function: Also in the automatic transmission of the present invention, the setting of each gear stage is as follows:
It is determined based on driving conditions such as throttle opening and vehicle speed. Therefore, if driving conditions such as throttle opening and vehicle speed change while driving in a predetermined gear position, the gear shift will change according to the changed driving condition. A stage is selected, and a combination of engagement and release of the frictional engagement means for setting the stage is selected.

In that case, the frictional engagement means to be engaged in order to set the target gear, the rotating member whose rotational speed changes due to the engagement of the frictional engagement means, and the variable rotational speed thereof cannot be known in advance. Therefore, in the automatic transmission of this invention,
Another frictional engagement means that is released in order to set the target gear stage, but can cause rotational fluctuations in the rotating member, more precisely, rotational fluctuations in the same direction as the rotational fluctuations accompanying the gear shift. The frictional engagement means is engaged in advance.

Therefore, a portion of the inertial energy that should be absorbed by the frictional engagement means engaged to set the target gear is absorbed by the other frictional engagement means. Further, after the start of the speed change control, together with the release operation of the other frictional engagement means,
The frictional engagement means for setting the target gear stage is engaged. Therefore, since both frictional engagement means are not engaged at the same time, the gear train is never locked.

Example Next, the present invention will be explained based on examples.

First, an example of a gear train in the embodiment will be explained.
In the example shown in FIG. 1, the gear train is constructed mainly of three sets of single pinion type planetary gear mechanisms 1, 2, and 3, and each element in each of these planetary gear mechanisms 1, 2, and 3 is as follows. It is connected and structured as follows. That is, the first
The carrier IC of the planetary gear mechanism 1 and the ring gear 3R of the third planetary gear mechanism 3 are connected to rotate together, and the ring gear 2R of the second planetary gear mechanism 2 and the carrier 3C of the third planetary gear mechanism 3 are connected so that they rotate together. Further, the sun gear IS of the first planetary gear mechanism 1 is connected to the carrier 2C of the second planetary gear mechanism 2 via the second clutch means 2, while the sun gear IS is connected to the carrier 2C of the second planetary gear mechanism 2 via the fourth clutch means 4. 2 sun gear 2S
and further connected to the carrier 2C of the second planetary gear mechanism 2.
is connected to the sun gear 3S of the third planetary gear mechanism 3 via a fifth clutch means 5.

Note that as a connection structure for each of the above-mentioned elements, a connection structure used in general automatic transmissions such as a hollow shaft, a solid shaft, or an appropriate connecting drum can be used.

The input shaft 4 is connected to an engine (not shown) via a power transmission means (not shown) such as a torque converter or a fluid coupling, and the input shaft 4 and the ring gear IR of the first planetary gear mechanism 1 are connected to each other. In between, there is a first
A clutch means 1 is provided, and a third clutch means 3 is provided between the input shaft 4 and the sun gear IS of the first planetary gear mechanism 1 to selectively connect the two.

Each of the above clutch means K1. 2. 3. The key point of K5 is to selectively connect and disconnect each of the above-mentioned members, and for example, it is engaged by a mechanism conventionally used in automatic transmissions, such as a hydraulic servo mechanism.・Wet type multi-disc clutches that are released, one-way clutches,
Alternatively, a configuration in which these wet type multi-disc clutches and one-way clutches are arranged in series or in parallel can be adopted as necessary. In addition, in practical use, since there are restrictions on the arrangement of each component, each clutch means Kl
, to 2. 3. 4. It goes without saying that an appropriate intermediate member such as a connecting drum may be interposed as a connecting member to 5.

Further, the first brake means B1 for selectively blocking the rotation of the sun gear 3S of the third planetary gear mechanism 3 is configured to prevent the rotation of the sun gear 3S of the third planetary gear mechanism 3.
and the transmission case (hereinafter simply referred to as the case) 6, and the carrier 2C of the second planetary gear mechanism 2.
A second brake means B2 for selectively preventing the rotation of the sun gear 2S of the second planetary gear mechanism 2 is provided between the carrier 2C and the case 6, and a third brake means B3 for selectively preventing the rotation of the sun gear 2S of the second planetary gear mechanism 2 is provided between the carrier 2C and the case 6. A fourth brake means B4 is provided between the sun gear 2S and the case 6, and between the sun gear IS and the case 6, and for selectively blocking the rotation of the sun gear IS of the first planetary gear mechanism 1. These brake means Bl, B2°B3. B4 can be configured with a wet multi-disc brake, a band brake, or a one-way clutch driven by a hydraulic servo mechanism conventionally used in general automatic transmissions, or a combination of these. In practical use, these brake means Bl, B2. B3. B4 and these brake means Bl
,B2. B3. Of course, an appropriate connecting member can be interposed between each element to be fixed by B4 or between the case 6 and the case 6.

An output shaft 5 that transmits rotation to the proveran shaft and a counter gear (not shown) is connected to the ring gear 2R of the second planetary gear mechanism 2 and the carrier 3C of the third planetary gear mechanism 3, which are connected to each other. There is.

In the automatic transmission with the configuration shown in Fig. 1, the main gears are five forward speeds and one reverse speed, and between the second forward speed and third speed there are so-called 2.2 speeds and 2nd and 5th speeds. , a plurality of gear stages can be set by adding the 27th gear stage and adding the so-called 3.2nd speed and 3.5th gear between the 3rd forward speed and the 4th forward speed. . In addition, in other gears other than 2nd, 2nd, 2.7th, 32nd, and 3.5th gears, the clutch means and brake means are engaged and engaged to set the gears.
There are a plurality of release combinations (so-called engagement/release patterns), which are shown in Table 1 as an operation table.

In Table 1, the ○ mark indicates engagement, the blank indicates disengagement, this mark indicates that engagement may be allowed, and the * mark indicates that the 1st gear 5 Clutch means 5, first brake means B1, etc. that do not cause a change in the gear ratio or rotational state even if released, 4th speed b
If released, the gear ratio does not change but the rotational state changes, such as the first brake means B1 in pattern m, and the fourth clutch means 4 or third brake means B3 in the pattern in column b of the second speed. This includes cases where the gear ratio and rotational state do not change even if the other means marked with an asterisk (*) are engaged and released. Also, 2nd speed, 3rd speed, 4th speed,
The columns labeled a, b, c, etc. for 5th gear and reverse gear indicate different rotational speeds of the rotating elements of the planetary gear mechanism among the engagement/disengagement patterns for setting the gear. It shows that it is an engagement/release pattern of objects, and also ■,■
.

The symbols . . . represent the types of engagement/disengagement patterns even though the rotational speeds of the rotating elements of the planetary gear mechanism do not differ.

(This page, blank space below) The engagement/disengagement patterns shown in Table 1 are engagement/disengagement patterns that are possible in principle, and in practical use, select one of them based on requirements such as power performance and speed change controllability. Each gear stage is selected and set based on driving conditions such as engine load represented by throttle opening and vehicle speed. When shifting gears in response to changes in driving conditions, the engagement/disengagement pattern of the friction engagement means is not directly changed to the engagement/disengagement pattern for setting the target gear, but rather Another frictional engagement means that is not involved in setting the gear stage is temporarily engaged, thereby causing a preliminary rotational fluctuation of the rotating member to execute the gear shift.

The electronic control unit (ECU) is a device that controls the setting of gears, the selection of engagement/disengagement patterns, and the engagement of frictional engagement means to generate preliminary rotational fluctuations during gear shifting. ) E and hydraulic control device C
is provided.

That is, the electronic control unit E performs calculations based on input data such as vehicle speed V to throttle opening θ, driving mode select signal, and chilled water temperature, and outputs a command signal to the hydraulic control device C. Hydraulic control device C
, the clutch means and brake means are engaged or released as appropriate by changing the hydraulic pressure supply/discharge route based on a command signal from the electronic control unit E, thereby engaging or disengaging any of the engagement/disengagement shown in Table 1. This is to be set in the pattern.

Among the gear changes performed in the automatic transmission shown in FIG. This is done as follows.

That is, the third speed is set according to the pattern in column C of Table 1 (a pattern in which the first clutch means is engaged with 1, the third clutch means with 3, the fourth clutch means with 4, and the first brake means B1 is engaged). When performing a power-on upshift to 4th gear from
2 will be directly applied to the clutch means, and the load of 2 will become excessive on the second clutch means. Therefore, in the automatic transmission shown in FIG. 1, a power-on upshift from the third speed to the fourth speed is executed according to the flowchart shown in FIG. First, in step 1, it is determined whether the shift from the third speed to the fourth speed is a power-on upshift based on input data such as the throttle opening θ, the amount of change thereof, and the vehicle speed V. If the judgment result is “yes”,
Proceeding to step 2, a command signal to release the first brake means B1 is output, followed by a step 3 to output a command signal to engage the third brake means B3. In this case, since the third clutch means 3 and the fourth clutch means 4 are engaged, when the third brake means B3 is engaged, the input shaft 4 is braked. Therefore, in step 4, it is determined whether the rotational speed N1 of the input shaft 4 is equal to or less than the first reference value α.

Note that the reference value α is a value appropriately determined according to the input shaft rotation speed at the start of the shift. The judgment result of this step 4 is “
When the answer is ``YES'', a command signal for engaging the second clutch means is output.

Since the load applied to the input shaft 4 further increases due to the engagement of the second clutch means, the input shaft rotation speed N continues to decrease, and at the point when the input shaft rotation speed Ni becomes equal to or less than the second reference value β ( When the judgment result in step 5 is YES), the third
A command signal for releasing the brake means B3 is output (step 7). Note that the second reference value β is a value determined according to the input shaft rotation speed at the time of starting the shift, and is a value smaller than the first reference value α.

Therefore, at the time when the second clutch means 2 starts to be engaged in order to set the fourth speed, the third brake means B3 is engaged to some extent and the rotational speed of the input shaft 4 is preliminarily lowered. The amount of inertial energy that must be absorbed by the second clutch means from the start of engagement until the second clutch is completely engaged is reduced.

On the other hand, if the judgment result in step l is "no", the third
The shift from 4th gear to 4th gear is a power-off upshift, and the torque from the engine tends to decrease, so in this case, the gear is shifted directly to 4th gear. That is, the first
A release command signal for the brake means Bl is outputted (step 8), and a second engagement command signal is outputted for the second clutch means (step 9). Even when the gears are directly shifted in this way, the engine speed decreases due to its own load, so an excessive load is not applied to the second clutch means 2, and there is an advantage that time lag can be prevented.

Therefore, by performing speed change control as described above,
The inertial energy associated with the change in input shaft rotation speed during gear shifting is
The third brake means B3, which is not engaged in order to set the fourth speed, and the second clutch means B3, which is engaged in order to set the fourth speed, share the absorption.
The load applied to the second clutch means 2 can be significantly reduced compared to the case where the gear is directly shifted from the second gear to the fourth gear. Further, since the brake means and clutch means for such speed change are engaged and released continuously and are not engaged at the same time, there is no risk of locking of the gear train.

By the way, the above-mentioned shift control in which the third brake means B3 is temporarily engaged during the shift is also effective when setting the third gear in the aWA pattern and power-on upshifting from that state to the fourth gear. It is. In other words, 3rd gear is 1st gear.
In the state set according to the pattern in column a of the table, the sun gear 2S of the second planetary gear mechanism 2 rotates in the opposite direction to the input shaft 4, while in the fourth gear, the sun gear 2S rotates at the same speed as the input shaft 4. Therefore, the rotational speed fluctuation increases, but since the sun gear 2S of the second planetary gear mechanism 2 can be braked by the third brake means B3, the third brake means B3 is applied before the fourth crunch means 4 during the gear shift. If you temporarily engage the
When the rotational speed of the sun gear 2S is increased from reverse rotation to near a stopped state, and as a result, when the fourth clutch means is engaged with 4 in order to set the 4th speed, the 4th clutch means is engaged with 4. The amount of inertial energy that should be absorbed by the
When powering off and upshifting to 4th speed with the pattern set in the column, it is sufficient to perform a so-called direct shift, as in the above example.

Note that this invention applies to the third speed and fourth speed explained in the above embodiment.
It is not limited only to upshifts between speeds,
The same applies to upshifts between other gears. Further, automatic transmissions to which the present invention can be applied are not limited to those having the above-mentioned gear train. .52, Japanese Patent Application No. 1-186991, Japanese Patent Application No. 1186992, Japanese Patent Application No. 205478, Japanese Patent Application No. 1-280957, etc. can.

Effects of the Invention As is clear from the above explanation, according to the automatic transmission of the present invention, inertial energy to be absorbed during gear shifting is absorbed by other friction coefficients that are not engaged in order to set the target gear. The frictional engagement means is configured to engage the frictional engagement means and partially absorb the energy, and the frictional engagement means is temporarily engaged prior to the frictional engagement means for setting the target gear. It is possible to reduce the load on the frictional engagement means and improve its durability without causing the gear train to lock, and since there is no risk of the gear train locking, speed change control becomes easier.

[Brief explanation of drawings]

FIG. 1 is a skeleton diagram showing the principle of an embodiment of the present invention, and FIG. 2 is a control flowchart for shifting. 1. 2.3...Planetary gear mechanism, IS, 2S, 3S
...Sun gear, 1. C, 2C, 3C...Carrier, IR, 2R, 311...Ring gear, 4...Input shaft, 5...Output shaft, C...Hydraulic control device, E.
...Electronic control unit.

Claims (1)

[Claims] By connecting or fixing each rotating member of a gear train mainly consisting of a plurality of sets of planetary gear mechanisms to each other through a combination of engagement and release of a plurality of frictional engagement means, a plurality of In an automatic transmission for a vehicle that sets a gear, the second gear is set prior to the frictional engagement means to be engaged when shifting from the first gear to the second gear. Temporarily engages another frictional engagement means to be released, thereby causing in advance a change in the rotational speed of a rotating member whose rotational speed changes with the shift from the first gear to the second gear. An automatic transmission for a vehicle, characterized in that the automatic transmission for a vehicle is provided with a control device that causes the predetermined frictional engagement means to engage the predetermined frictional engagement means as well as the release operation of the other frictional engagement means.