JP2009216242A - Automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic transmission that achieves forward eight speeds while having three sets of planetary gears and six friction elements and enables the acquisition of a lower integration idling speed ratio, especially, in a forward speed change. <P>SOLUTION: The automatic transmission includes a front planetary gear, a mid-planetary gear, and a rear planetary gear. An input shaft IN is always connected with a rear sun gear RR-S. An output shaft OUT is always connected to a rear carrier RR-PC. A front sun gear FR-S is always locked to a transmission case 1. A mid-ring gear MID-R and a rear ring gear RR-R are always connected with each other by a first rotating member M1. A front ring gear FR-R and a mid-sun gear MID-S are always connected with each other by a second rotating member M2. There are provided a low&reverse brake L&R/B, a clutch 146/C, a clutch 38/C, a mid-clutch MID/C, a high&reverse clutch H&R/C, and a clutch 7/C so as to achieve forward eight speeds and reverse one speed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a stepped automatic transmission applied as a transmission of a vehicle.

  Conventionally, for example, a technique described in Patent Document 1 is known as an automatic transmission that achieves eight forward speeds using three sets of planetary gears. Patent Document 1 discloses an automatic transmission that achieves eight forward speeds using six friction elements in total including three planetary gears, four clutches as friction elements, and two brakes. Of the two brakes, the B-1 brake is engaged at the 1st and reverse speeds, and the B-2 brake is engaged at the 1st and 8th speeds.

WO2005 / 026579 (see FIG. 3)

  Here, the ratio of the relative rotational speed of the released friction element to the input rotational speed of the transmission is defined as the idling speed ratio (a parameter indicating the relative rotational speed with respect to the input rotational speed 1). By accumulating the idle speed ratios of the released friction elements for each shift speed (hereinafter referred to as an accumulated idle speed ratio), the degree of relative rotation of the friction elements for each shift speed in the transmission can be evaluated. In general, as the relative rotational speed increases, the horsepower loss of the friction element tends to increase. By using this integrated idling speed ratio, the fuel efficiency can be judged to some extent. In particular, when the input rotational speed is a relatively low rotational speed or when the number of brakes is large as a breakdown of the released friction elements, this tendency becomes significant.

  In the automatic transmission disclosed in Patent Document 1, the gear ratios of the three rows of planetary gears were set to α1 = 0.463, α2 = 0.594, and α3 = 0.405, respectively, and the integrated idling speed ratio was calculated for each gear position. FIG. 5 is a diagram illustrating an accumulated idling speed ratio for each gear position. As indicated by ▲ in FIG. 5, the automatic transmission described in Patent Document 1 has a problem that the accumulated idling speed ratio is high and the fuel consumption is deteriorated at the forward shift stage where the usage frequency is high.

  An object of the present invention is an automatic transmission capable of achieving eight forward speeds by using three sets of planetary gears and six friction elements, and obtains a low integrated idling speed ratio particularly at forward gears. It is an object of the present invention to provide an automatic transmission that can be used.

  To achieve the above object, in an automatic transmission according to the present invention, a first planetary gear having a first rotating element, a second rotating element, and a third rotating element, and a fourth rotating element, , A second planetary gear having a fifth rotating element and a sixth rotating element, a third planetary gear having a seventh rotating element, an eighth rotating element and a ninth rotating element. An automatic transmission capable of shifting to at least a forward 8-speed gear and outputting torque from the input shaft to the output shaft by appropriately fastening and releasing the six friction elements. The input shaft is always connected to the seventh rotating element, the output shaft is always connected to the eighth rotating element, and the first rotating element is always locked, The sixth rotating element and the ninth rotating element are connected to form a first rotating member. The third rotating element and the fourth rotating element are connected to form a second rotating member, and the six friction elements are first elements capable of locking the rotation of the fifth rotating element. Between the second rotating element and the eighth rotating element, the second friction element selectively connecting the second rotating element and the eighth rotating element, and the fourth rotating element and the eighth rotating element. A third friction element that selectively connects the second rotation element, a fourth friction element that selectively connects between the second rotation element and the fifth rotation element, the second rotation element, and the A fifth friction element that selectively connects the seventh rotation element, and a sixth friction element that selectively connects two rotation elements of the second planetary gear. And at least 8 forward speeds and 1 reverse speed are achieved by combining two of the six friction elements at the same time. And wherein the door.

  Therefore, in the automatic transmission of the present invention, the forward eight speed can be achieved with six friction elements. At this time, the integrated idling speed ratio for each forward shift stage can be lowered, and the fuel efficiency in the low speed region can be improved.

1 is a skeleton diagram illustrating an automatic transmission according to a first embodiment. It is a figure which shows the coupling | bonding table | surface of the friction element in the automatic transmission of Example 1. FIG. It is a figure which shows the specific example of the reduction ratio in the automatic transmission of Example 1. FIG. 3 is a reduction ratio map in which reduction ratios for each gear stage in the automatic transmission according to the first embodiment are plotted. It is a figure showing the integrated idling speed ratio for every gear stage in Example 1 and Patent Document 1. It is a skeleton figure which shows the automatic transmission of Example 2. FIG. FIG. 6 is a skeleton diagram showing an automatic transmission according to a third embodiment. FIG. 6 is a skeleton diagram showing an automatic transmission according to a fourth embodiment. FIG. 10 is a skeleton diagram showing an automatic transmission according to a fifth embodiment. FIG. 10 is a skeleton diagram showing an automatic transmission according to a sixth embodiment.

  Hereinafter, the form which implement | achieves the transmission mechanism of the stepped automatic transmission of this invention is demonstrated based on Example 1 shown in drawing. First, the configuration will be described. 1 is a skeleton diagram showing a transmission mechanism of a stepped automatic transmission according to a first embodiment, FIG. 2 is a table of friction elements in the automatic transmission according to the first embodiment, FIG. 3 is a specific example of a reduction ratio, and FIG. Is a reduction ratio map in which the reduction ratio for each forward gear is plotted.

  As shown in FIG. 1, the automatic transmission according to the first embodiment has three single planetary gear sets, a planetary gear set PGFR (first planetary gear) and a mid planetary gear PGMID (second planetary gear), as gear trains. Gear) and a rear planetary gear PGRR (third planetary gear). Front planetary gear PGFR consists of front sun gear FR-S (first rotating element), front ring gear FR-R (third rotating element), front pinion FR-S meshing with front sun gear FR-S and front ring gear FR-R. P. The mid planetary gear PGMID is a mid-sun gear MID-S (fourth rotating element), a mid-ring gear MID-R (sixth rotating element), and a mid-pinion MID-M that meshes with the mid-sun gear MID-S and mid-ring gear MID-R. P. The rear planetary gear PGRR includes a rear sun gear RR-S (seventh rotating element), a rear ring gear RR-R (ninth rotating element), a rear pinion RR-P meshing with the rear sun gear RR-S and the rear ring gear RR-R, Have Front pinion FR-P, mid pinion MID-P and rear pinion RR-P are respectively front carrier FR-PC (second rotating element), mid carrier MID-PC (fifth rotating element) and rear carrier RR-PC ( It is supported rotatably with respect to the eighth rotating element).

  The input shaft IN is always connected to the rear sun gear RR-S. The output shaft OUT is always connected to the rear carrier RR-PC. The front sun gear FR-S is always locked to the transmission case 1. The mid ring gear MID-R and the rear ring gear RR-R are always connected by the first rotating member M1. The front ring gear FR-R and the mid sun gear MID-S are always connected by the second rotating member M2.

  The automatic transmission has one brake, low & reverse brake L & R / B (first friction element), five clutches 146 clutch 146 / C (second friction element), 38 clutch 38 / C ( 3rd friction element), mid clutch MID / C (4th friction element), high & reverse clutch H & R / C (5th friction element) and 7 clutch 7 / C (6th friction element) are provided ing.

  The low & reverse brake L & R / B is provided between the mid carrier MID-PC and the transmission case 1 and selectively locks the rotation of the mid carrier MID-PC to the transmission case 1. The 146 clutch 146 / C is provided between the front carrier FR-PC and the rear carrier RR-PC, and selectively connects the front carrier FR-PC and the rear carrier RR-PC. The 38 clutch 38 / C is provided between the front ring gear FR-R and the rear carrier RR-PC, and selectively connects the front ring gear FR-R and the rear carrier RR-PC. The mid clutch MID / C is provided between the front carrier FR-PC and the mid carrier MID-PC, and selectively connects the front carrier FR-PC and the mid carrier MID-PC. The 7 clutch 7 / C is provided between the front ring gear FR-R and the mid carrier MID-PC, and selectively connects the front ring gear FR-R and the mid carrier MID-PC.

  The function required for the 7-clutch 7 / C is the integral rotation of the mid planetary gear PGMID. Since the front ring gear FR-R and the mid-sun gear MID-S are connected by the second rotating member M2, in other words, the 7-clutch 7 / C is between the two rotating elements of the mid-planetary gear PGMID (mid-carrier MID -It can be said that it is a friction element that selectively connects the PC and mid-sun gear MID-S). The high & reverse clutch H & R / C is provided between the front carrier FR-PC and the rear sun gear RR-S, and selectively connects the front carrier FR-PC and the rear sun gear RR-S.

  The output shaft OUT is provided with an output gear or the like, and rotational driving force is transmitted to the drive wheels via a differential gear and a drive shaft (not shown). In the case of the first embodiment, the outer periphery of the output shaft OUT is not blocked by other members or the like, so that it can be applied to both FF vehicles and FR vehicles.

  The relationship of coupling (fastening) of the friction elements at each gear stage will be described with reference to the coupling table of FIG. 2 (shift control means). In the table, a circle indicates fastening and a blank indicates release.

  First, the time of advance will be described. First gear is achieved by engaging low & reverse brake L & R / B and 146 clutch 146 / C. The second speed is achieved by engaging the low & reverse brake L & R / B and the mid clutch MID / C. The third speed is achieved by engaging 38 clutch 38 / C and mid clutch MID / C. The fourth speed is achieved by engaging the 146 clutch 146 / C and the mid clutch MID / C. The fifth gear is achieved by engaging the mid clutch MID / C and the high & reverse clutch H & R / C. The 6th speed is achieved by engaging 146 clutch 146 / C and high & reverse clutch H & R / C. The 7th speed is achieved by engaging the high & reverse clutch H & R / C and 7 clutch 7 / C. The eighth speed is achieved by engaging 38 clutch 38 / C and high & reverse clutch H & R / C. The reverse speed is achieved by engaging low & reverse brake L & R / B and high & reverse clutch H & R / C.

Next, a specific example of the reduction ratio in the first embodiment will be described with reference to FIG. Here, the gear ratio of the front planetary gear PGFR ρ _FR = Z _FR-S / Z _FR-R = 0.50, the gear ratio of the mid planetary gear PGMID ρ _MID = Z _MID-S / Z _MID-R = 0.53, the rear planetary gear PGRR This is explained using an example in which the tooth ratio of ρ _RR = Z _RR-S / Z _RR-R = 0.45. Z _FR-S , Z _MID-S , Z _RR-S , Z _FR-R , Z _MID-R and Z _RR-R represent the number of teeth of each gear.

The reduction ratio i ₁ of the _first forward speed is
i ₁ = (1 + ρ _RR + ρ _MID + ρ _MID ρ _FR ) / ρ _RR
When a specific numerical value is substituted,
The reduction ratio i ₁ for the _first forward speed is i ₁ = 5.00, and the reciprocal of the reduction ratio is 0.20.

The reduction ratio i ₂ of the _second forward speed is
i ₂ = (1 + ρ _RR ) / ρ _RR
When a specific numerical value is substituted,
The reduction ratio i ₂ of the _second forward speed is i ₂ = 3.22, and the reciprocal of the reduction ratio is 0.31.

The reduction ratio i ₃ of the _3rd forward speed is
i ₃ = (ρ _RR + ρ _FR + ρ _FR ρ _RR + ρ _MID ρ _FR ) / (ρ _RR (1 + ρ _FR ))
When a specific numerical value is substituted,
The reduction ratio i ₃ for the _third forward speed is i ₃ = 2.13, and the reciprocal of the reduction ratio is 0.47.

The reduction ratio i ₄ of the forward 4th speed is
i ₄ = (ρ _RR + ρ _MID ρ _FR ) / ρ _RR
When a specific numerical value is substituted,
The reduction ratio i ₄ for the _fourth forward speed is i ₄ = 1.59, and the reciprocal of the reduction ratio is 0.63.

The reduction ratio i ₅ of the _5th forward speed is
i ₅ = (1 + ρ _RR ) / (1 + ρ _RR −ρ _MID ρ _FR )
When a specific numerical value is substituted,
The reduction ratio i ₅ for the _fifth forward speed is i ₅ = 1.23, and the reciprocal of the reduction ratio is 0.81.

The reduction ratio i ₆ for the _6th forward speed is
i ₆ = 1.0
Without needing to substitute a specific numerical value,
The reduction ratio i ₆ for the _sixth forward speed is i ₆ = 1.0, and the reciprocal of the reduction ratio is 1.0.

The reduction ratio i _{7 for} forward 7 speed is
i ₇ = (1 + ρ _RR ) / (1 + ρ _RR + ρ _FR )
When a specific numerical value is substituted,
The reduction ratio i ₇ for the _seventh forward speed is i ₇ = 0.74, and the reciprocal of the reduction ratio is 1.34.

The reduction ratio i ₈ for the _8th forward speed is
i ₈ = 1 / (1 + ρ _FR )
When a specific numerical value is substituted,
The reduction ratio i ₈ for the _eighth forward speed is i ₈ = 0.67, and the reciprocal of the reduction ratio is 1.50.

The reverse speed reduction ratio i _R is
i _R = − (1 + ρ _RR ) / (ρ _MID + ρ _MID ρ _FR −ρ _RR )
When a specific numerical value is substituted,
The reverse speed reduction ratio i _R is i _R = −4.12, and the reciprocal of the reduction ratio is −0.24.

  FIG. 4 is a reduction ratio map in which the reduction ratio for each gear stage is plotted. As shown in FIG. 4, the reduction ratio is reduced in a geometric series as the gear stage is increased, thereby achieving a rhythmical shift without a sense of incompatibility when shifting according to the vehicle speed.

[Effect of Example 1]
Effect based on the accumulated idling speed ratio FIG. 5 is a diagram showing the accumulated idling speed ratio for each gear position in the first embodiment. As indicated by ● in FIG. 5, in the automatic transmission of the first embodiment, the integrated idling speed ratio is lower than that in Patent Document 1 at the forward shift stage where the frequency of use is high, and the fuel efficiency is improved mainly in the low speed region. can do.

-Effect of the whole skeleton In the first embodiment, an automatic transmission with eight forward speeds and one reverse speed capable of securing an appropriate reduction ratio is realized, although it is a simple and few component elements of three simple planets and six friction elements. be able to.

・ Effects of using three simple planetary sets By using three simple planetary sets, it is possible to suppress the deterioration of gear noise compared to the case of using a double pinion, and it is not necessary to reduce the pinion diameter. Deterioration of durability can be suppressed. In addition, the outer diameter of the planetary gear can be reduced, and the size of the transmission can be reduced.

・ Effect based on the gear ratio The gear ratios ρ ₁ , ρ ₂ , and ρ _{3 of} each planetary gear set are all close to an intermediate value of 0.5. Therefore, the range in which the three gear ratios can be freely set is wide, and the degree of freedom of the reduction gear ratio can be increased.

・ Effects based on forward ratio coverage Forward ratio coverage (gear ratio width) means the lowest gear ratio / highest gear ratio, and the larger the value, the greater the value at each forward gear. It can be said that the gear ratio setting freedom is increased. The specific numerical value in the first embodiment is that the reduction ratio of the first forward speed is 5.00 and the reduction ratio of the eighth forward speed is 0.67. Therefore, the 1-8 speed ratio coverage is 7.50, and the sufficient ratio coverage is obtained. It can be secured. Therefore, for example, it is also useful as a transmission of a vehicle in which a diesel engine having a narrower engine speed range as a power source than a gasoline engine and having a low torque when compared with the same displacement is used as a power source.

Effect based on 1-R ratio The ratio of the speed ratio of the first reverse speed and the speed ratio of the first forward speed (speed ratio of the first reverse speed / speed ratio of the first forward speed: hereinafter referred to as “1-R ratio”) Since the value is close to 1, more specifically 0.824, there is no significant difference in the acceleration feeling of the vehicle with respect to the depression and depression of the accelerator pedal when moving forward and backward, and the problem of deterioration of drivability can be avoided. it can.

  Here, the 1-R ratio will be described supplementarily. When the 1-R ratio cannot be set to an appropriate value, for example, when the 1-R ratio becomes a small value, the output torque with respect to the accelerator opening greatly differs between the first forward speed and the first reverse speed. If the vehicle's feeling of acceleration with respect to depression or depression of the accelerator pedal differs greatly between forward and reverse, the first forward speed and the first reverse speed are common in that they are used when the vehicle starts. There is a problem of getting worse. From this point of view, it was introduced as one of the drivability indicators.

・ Effects based on the number of switching friction elements during gear shifting Temporarily release one or more friction elements and fasten two or more friction elements, or release two or more friction elements and one during gear shifting When the above friction elements are fastened, the control of timing and torque of fastening and releasing of the friction elements becomes complicated. Therefore, from the viewpoint of avoiding complicated shift control, it is preferable to release one friction element and fasten one friction element. This is prevention of so-called double change. In the first embodiment, the shift is performed with the low & reverse brake L & R / B being engaged from the first forward speed to the second forward speed, and the mid clutch MID / C is engaged from the second forward speed to the fifth forward speed. Shifting is performed in a state of being performed, and from 5th forward speed to 8th forward speed is performed with the high & reverse clutch H & R / C being engaged. That is, the shift from the first forward speed to the eighth forward speed to the adjacent gear stage and the one-step jump shift (except for the one-step jump shift from the first forward speed to the third forward speed) are all one friction element. This can be achieved by changing gears by releasing the gear and fastening one friction element. Therefore, complication of control at the time of shifting can be avoided.

・ Effect based on layout
(i) As shown in the skeleton diagram of FIG. 1, the automatic transmission of the first embodiment has an input shaft IN of a planetary gear with three sets of low & reverse brake L & R / B, mid clutch MID / C and 7 clutch 7 / C. It is arranged intensively on the side. Similarly, 38 clutch 38 / C, 146 clutch 146 / C, and high & reverse clutch H & R / C are intensively arranged. That is, it is necessary to supply a fastening hydraulic pressure or the like to the clutch or the brake, and this supply oil passage must be supplied from a fixed member. At this time, since the friction elements are arranged in a concentrated manner, the distance from the fixed wall where the oil passage is formed can be substantially uniformed or shortened, so that the controllability is excellent and the oil passage is also managed. It becomes easy.

  In particular, an oil pump or the like that is generally driven by an engine is disposed on the input side, and an oil pump cover or the like that supports the oil pump is disposed. Since this cover is disposed so as to close the transmission case 1, it is effective as a communication passage between the control valve unit and each rotary element. In Example 1, since it is concentratedly arranged on the input side, it is easy to use this cover or the like, and it is easier to handle the oil passage.

  (ii) Further, as shown in the skeleton diagram of FIG. 1, the rotating member passing through the outer peripheral side of the planetary gear set has a single layer structure of only the rotating member that rotates integrally with the mid carrier MID-PC. The automatic transmission constantly supplies lubricating oil to gears, bearings, and the like that are rotating elements for the purpose of cooling and lubrication. Further, this lubrication is generally supplied by centrifugal force from the axial center side. At this time, if the discharge performance of the lubricating oil is deteriorated on the outer peripheral side, the oil temperature rises and the durability of the friction element and the bearing member (not shown) is lowered. In the first embodiment, as described above, since the rotating member passing through the outer peripheral side of the planetary gear set has a single layer structure, the oil discharge performance is not deteriorated, the oil temperature rise is suppressed, and the durability is improved. Improvements can be made.

  (iii) In particular, there are few members passing through the outer peripheral side of the output-side planetary gear, and the size of the output-side transmission can be reduced. This means that, when mounted on a rear wheel drive vehicle, if the output side has a reduced diameter, the vehicle mountability is significantly improved.

  (iv) Since the automatic transmission of the first embodiment is an automatic transmission that can be input from one side of the planetary gear set and output from the other side, either a front-wheel drive vehicle or a rear-wheel drive vehicle can be used. The application range of the automatic transmission can be widened.

  Next, Example 2 will be described. Since the basic configuration is the same as that of the first embodiment, only different points will be described.

  FIG. 6 is a skeleton diagram showing the second embodiment. In the second embodiment, the one-way clutch OWC is arranged in parallel with the low & reverse brake L & R / B. A one-way clutch OWC for low gears may be provided to simplify shift control and eliminate excessive engine braking during normal driving during upshifts with large torque steps such as low gears. preferable.

  For this purpose, in the case of the first embodiment, the one-way clutch OWC for the low gear stage is in parallel with the low & reverse brake L & R / B that is released when upshifting from the second forward speed to the third forward speed. Will be provided. The low & reverse brake L & R / B is a brake that selectively locks the mid carrier MID-PC to the transmission case 1. The mid carrier MID-PC rotates forward (engine rotation) when shifting from 2nd to 3rd gear. In order to place the one-way clutch OWC in the low & reverse brake L & R / B, the rotation direction of this mid carrier MID-PC makes the low & reverse brake L & R / B released. It is necessary to perform forward rotation at all gear positions.

  If a negative rotation occurs at any of the gear positions, another friction element that can switch the operation / non-operation of this one-way clutch OWC must be added in series with the one-way clutch OWC. This is not very useful. Therefore, when the rotational speed of the mid carrier MID-PC at all the shift speeds is examined in the first embodiment, the mid carrier MID-PC is normally rotated at all the shift speeds. Therefore, by simply configuring the one-way clutch OWC in parallel with the mid carrier MID-PC, it is possible to simplify the control logic while avoiding a significant increase in parts, resulting in excessive engine braking during normal driving. Can be suppressed.

  In Example 2, since the low & reverse brake L & R / B is engaged in the first and second gears, the low & reverse brake L & R / B is released for downshifts during coasting. The downshift from the third speed to the second speed may be performed as it is, and the downshift from the second speed to the first speed may be performed. At this time, only the release control of the 38 clutch 38 / C is performed at the time of downshift from the 3rd speed to the 2nd speed, and at the downshift from the 2nd speed to the 1st speed, the mid clutch MID / C is released and the 146 clutch 146 / C will be concluded.

  Next, Example 3 will be described. Since the basic configuration is the same as that of the first embodiment, only different points will be described. FIG. 7 is a skeleton diagram showing the speed change mechanism of the stepped automatic transmission according to the third embodiment. The friction element coupling table shown in FIG. 2 of the first embodiment, the specific example of the reduction ratio shown in FIG. 3, and the reduction ratio map plotting the reduction ratio for each forward shift stage shown in FIG. Is omitted.

  In the first embodiment, the 7-clutch 7 / C is provided between the front ring gear FR-R and the mid carrier MID-PC, and as a specific arrangement, is arranged on the input side with respect to the front planetary gear PGFR. On the other hand, in the third embodiment, the 7 clutch 7 / C is provided between the mid ring gear MID-R and the mid carrier MID-PC, and the specific arrangement is in the vicinity of the mid planetary gear PGMID, particularly the mid planetary gear PGMID and the rear planetary gear. The difference is that it is placed between PGRR. That is, since the function required for the 7 clutch 7 / C is the integral rotation of the mid planetary gear PGMID, between the two rotating elements of the mid planetary gear PGMID (mid carrier MID-PC and mid ring gear MID-R) From the point of view of selectively connecting between the two, substantially the same as the first and second embodiments.

  Example 3 can obtain the same effect as Example 1 by the above-mentioned composition. However, with respect to the effects shown in “• Effects based on layout / (i)” in Example 1, the 7 clutch 7 / C is separated from the concentrated arrangement of other friction elements, but the other 5 There is no change in the fact that the friction elements are concentratedly arranged, and it is needless to say that the effect described in the first embodiment “effects based on the layout / (i)” can be obtained by the concentrated arrangement of the other five friction elements. .

  Next, Example 4 will be described. Since the basic configuration is the same as that of the third embodiment, only different points will be described. FIG. 8 is a skeleton diagram showing the fourth embodiment. In the fourth embodiment, the one-way clutch OWC is arranged in parallel with the low & reverse brake L & R / B. Thereby, the same effect as the effect described in Example 2 can be obtained.

  Next, Example 5 will be described. Since the basic configuration is the same as that of the first embodiment, only different points will be described. FIG. 9 is a skeleton diagram showing the speed change mechanism of the stepped automatic transmission according to the fifth embodiment. The friction element coupling table shown in FIG. 2 of the first embodiment, the specific example of the reduction ratio shown in FIG. 3, and the reduction ratio map plotting the reduction ratio for each forward shift stage shown in FIG. Is omitted.

  In the first embodiment, the 7-clutch 7 / C is provided between the front ring gear FR-R and the mid carrier MID-PC, and as a specific arrangement, is arranged on the input side with respect to the front planetary gear PGFR. On the other hand, in the fifth embodiment, the 7 clutch 7 / C is provided between the mid ring gear MID-R and the mid sun gear MID-S, and the specific arrangement is in the vicinity of the mid planetary gear PGMID, particularly the mid planetary gear PGMID and the rear planetary gear. The difference is that it is placed between PGRR. That is, since the function required for the 7 clutch 7 / C is the integral rotation of the mid planetary gear PGMID, between the two rotation elements of the mid planetary gear PGMID (mid carrier MID-PC and mid sun gear MID-S) From the viewpoint of selectively connecting between the two), it is substantially the same as the first to fourth embodiments.

  In the fifth embodiment, the same effect as that of the first embodiment can be obtained by the above configuration. However, with respect to the effects shown in “• Effects based on layout / (i)” in Example 1, the 7 clutch 7 / C is separated from the concentrated arrangement of other friction elements, but the other 5 There is no change in the fact that the friction elements are concentratedly arranged, and it is needless to say that the effect described in the first embodiment “effects based on the layout / (i)” can be obtained by the concentrated arrangement of the other five friction elements. .

  Next, Example 6 will be described. Since the basic configuration is the same as that of the fifth embodiment, only different points will be described. FIG. 10 is a skeleton diagram showing the sixth embodiment. In the sixth embodiment, the one-way clutch OWC is arranged in parallel with the low & reverse brake L & R / B. Thereby, the same effect as the effect described in Example 2 can be obtained.

  Although Embodiments 1 to 6 have been described above, the fastening relationship of the rotating elements of each planetary gear may be another fastening relationship. In the first embodiment, the planetary gears are arranged in the order of front, mid, and rear. However, the arrangement order may be appropriately changed.

1 Transmission case
IN input shaft
OUT output shaft
PGFR Front planetary gear (first planetary gear)
PGMID Mid planetary gear (second planetary gear)
PGRR Rear planetary gear (third planetary gear)
FR-S Front sun gear (first rotating element)
FR-PC front carrier (second rotating element)
FR-R front ring gear (third rotating element)
MID-S mid sun gear (fourth rotating element)
MID-PC Mid carrier (5th rotating element)
MID-R mid ring gear (sixth rotating element)
RR-S Rear sun gear (seventh rotating element)
RR-PC Rear carrier (8th rotating element)
RR-R Rear ring gear (9th rotating element)
L & R / B Low & Reverse brake (first friction element)
146 / C 146 clutch (second friction element)
38 / C 38 clutch (third friction element)
MID / C mid clutch (fourth friction element)
H & R / C High & Reverse Clutch (5th friction element)
7 / C 7 clutch (6th friction element)
M1 1st rotation member
M2 Second rotating member
OWC one-way clutch

Claims (2)

A first planetary gear having a first rotating element, a second rotating element, and a third rotating element;
A second planetary gear having a fourth rotating element, a fifth rotating element, and a sixth rotating element;
A third planetary gear having a seventh rotating element, an eighth rotating element, and a ninth rotating element;
6 friction elements,
With
In an automatic transmission capable of shifting to at least a forward 8-speed gear stage by appropriately fastening and releasing the six friction elements and outputting torque from the input shaft to the output shaft,
The input shaft is always connected to the seventh rotating element;
The output shaft is always connected to the eighth rotating element;
The first rotating element is always locked;
The sixth rotating element and the ninth rotating element are connected to form a first rotating member,
The third rotating element and the fourth rotating element are connected to form a second rotating member,
The six friction elements are:
A first friction element capable of locking the rotation of the fifth rotation element;
A second friction element that selectively connects between the second rotation element and the eighth rotation element;
A third friction element that selectively connects between the fourth rotation element and the eighth rotation element;
A fourth friction element that selectively connects between the second rotation element and the fifth rotation element;
A fifth friction element that selectively connects between the second rotation element and the seventh rotation element;
A sixth friction element for selectively connecting two rotating elements of the second planetary gear;
Consisting of
An automatic transmission characterized in that at least eight forward speeds and one reverse speed are achieved by combining two of the six friction elements simultaneously engaged. The automatic transmission according to claim 1, wherein
The combination of two simultaneous engagements of the six friction elements is the simultaneous engagement of the first friction element and the second friction element, the first friction element and the fourth friction element as a forward shift stage. Simultaneous engagement of friction elements, simultaneous engagement of the third friction element and the fourth friction element, simultaneous engagement of the second friction element and the fourth friction element, the fourth friction element and the fifth The second friction element and the fifth friction element at the same time, the fifth friction element and the sixth friction element at the same time, the third friction element and the second friction element. 5. An automatic transmission which is a combination of simultaneous engagement of five friction elements, and is the simultaneous engagement of the first friction element and the fifth friction element as a reverse gear.

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