JP5362684B2 - Automatic transmission - Google Patents

Description

  The present invention relates to an automatic transmission that includes an input shaft that is rotatably supported in a transmission case and that is rotated by transmission of power from a drive source, and that rotates the input shaft in multiple stages and outputs it from an output member.

  Conventionally, an automatic operation capable of performing eight forward gears using the first planetary gear mechanism for input, the second and third planetary gear mechanisms for shifting, and the six engaging mechanisms. A transmission is known (see, for example, Patent Document 1).

  In Patent Document 1, the first planetary gear mechanism for input includes a first sun gear and a first ring gear that mesh with each other, one meshing with the first sun gear and the other meshing with the first ring gear. It is constituted by a so-called double pinion type planetary gear mechanism comprising a first carrier that pivotally supports one pinion so as to rotate and revolve.

  The first planetary gear mechanism decelerates the rotational speed of a fixed element in which a first sun gear is fixed to a transmission case, an input element in which a first carrier is connected to an input shaft, and a first carrier in which a first ring gear is an input element. Output element.

  In addition, the two planetary gear mechanisms for shifting are engaged with the second sun gear, the third sun gear, and the second ring gear integrated with the third ring gear, and one of them meshes with the second sun gear and the second ring gear. The other is a Ravigneaux type planetary gear mechanism comprising a second carrier that pivotally supports and revolves a pair of second pinions meshing with the third sun gear.

  This Ravigneaux type planetary gear mechanism has a first rotation element, a first rotation element, and a second rotation element in order with an interval corresponding to the gear ratio in a collinear diagram (a ratio of relative rotation speeds of the rotation elements can be represented by a straight line). Assuming that the second rotating element, the third rotating element, and the fourth rotating element, the first rotating element is the second sun gear, the second rotating element is the second carrier integrated with the third carrier, and the third rotating element is the third ring gear. The second ring gear and the fourth rotating element integrated with each other become the third sun gear.

  In addition, as an engagement mechanism, a first wet multi-plate clutch that releasably connects a first ring gear that is an output element of the first planetary gear mechanism and a fourth rotation element that is a third sun gear, an input shaft, and a second carrier And a second wet multi-plate clutch for releasably connecting a first rotary element comprising a first ring gear and a second sun gear as output elements. A fourth wet multi-plate clutch for releasably connecting the first carrier as the input element and the first rotating element comprising the second sun gear, and the first rotating element comprising the second sun gear to be disengageable to the transmission case. A first brake for fixing, and a second brake for releasably fixing the second rotating element including the second carrier to the transmission case.

  According to the above configuration, the first speed is established by engaging the first wet multi-plate clutch and the second brake, and the second speed is established by engaging the first wet multi-plate clutch and the first brake. A stage is established, and a third speed stage is established by engaging the first wet multi-plate clutch and the third wet multi-plate clutch, and the first wet multi-plate clutch and the fourth wet multi-plate clutch are engaged. This establishes the fourth gear.

  Further, the fifth speed stage is established by engaging the first wet multi-plate clutch and the second wet multi-plate clutch, and 6 by engaging the second wet multi-plate clutch and the fourth wet multi-plate clutch. By establishing the first gear, engaging the second wet multi-plate clutch and the third wet multi-plate clutch, the seventh gear is established, and by engaging the second wet multi-plate clutch and the first brake. The eighth gear is established.

JP 2005-273768 A

  In the above-described conventional example, the number of engagement mechanisms engaged at each shift stage is two. Therefore, the friction loss due to dragging of the remaining four engagement mechanisms that are open increases, resulting in a problem that the efficiency of the automatic transmission deteriorates.

  An object of the present invention is to provide an automatic transmission which can reduce friction loss in view of the above points.

  [1] The present invention includes an input shaft that is rotatably supported in a transmission case and that is rotated by transmission of power from a drive source. It is an automatic transmission that outputs four first to fourth planetary gear mechanisms each having three elements, which are a sun gear, a carrier, and a ring gear, and the three elements of the first planetary gear mechanism are rotated relative to each other. The first element, the second element, and the third element are arranged in the order of arrangement at intervals corresponding to the gear ratio in the collinear diagram in which the speed ratio can be represented by a straight line, and the three elements of the fourth planetary gear mechanism are collinear. The fourth element, the fifth element, and the sixth element are arranged in order in the interval corresponding to the gear ratio in the figure, respectively, and each of the second planetary gear mechanism and the third planetary gear mechanism constitutes four rotating elements, These four rotating elements are aligned in the collinear diagram. The first rotating element, the second rotating element, the third rotating element, and the fourth rotating element are connected in order to connect the third element and the third rotating element to form a first coupling body, and the fifth element and the first rotating element are respectively configured. The rotating element is connected to form a second connecting body, the first element is connected to the input shaft, the sixth element is connected to the output member, and the second connecting body is fixed to the transmission case as an engagement mechanism. A first brake that can be freely fixed, a second brake that can fix the second rotating element to the transmission case, a third brake that can fix the fourth element to the transmission case, and the second and sixth elements are connected to each other. A first clutch that can freely connect the first element and the second rotating element, and a third clutch that can freely connect the first element and the fourth rotating element. Of the total of six engagement mechanisms, including the three brakes and the first to third clutches, By the Kutomo three engaging mechanism in a coupling state or a fixed state, and establishes the respective gear stages.

  According to the present invention, as will be apparent from the description of the embodiment described later, among the total of six engagement mechanisms of the three brakes and the three clutches, the three engagement mechanisms are engaged and connected at each shift stage. State or fixed state. Therefore, the number of engagement mechanisms opened at each gear stage is 3, and the friction loss due to the open engagement mechanisms is smaller than that in the conventional case where four engagement mechanisms are opened at each gear stage. Can be reduced.

  [2] In the present invention, the second planetary gear mechanism is disposed radially outward of the first planetary gear mechanism, and the ring gear of the first planetary gear mechanism and the sun gear of the second planetary gear mechanism are integrally configured. Is preferred.

  According to this, since the second planetary gear mechanism is arranged radially outward of the first planetary gear mechanism, the axial length of the automatic transmission can be shortened, and the vehicle, particularly FF (front engine / front drive) It is possible to improve the mountability of the) type vehicle.

  [3] In the present invention, it is preferable that the second brake is constituted by a meshing mechanism. According to this, the friction loss at the meshing mechanism as the second brake can be suppressed at the shift speed at which the second brake is released. For this reason, the friction loss can be further reduced as the entire automatic transmission.

  [4] In the present invention, it is preferable that the first clutch is constituted by a meshing mechanism. Accordingly, it is possible to suppress friction loss at the meshing mechanism serving as the first clutch at the gear position where the first clutch is in the released state. For this reason, the friction loss can be further reduced as the entire automatic transmission.

  [5] In the present invention, the second brake can be switched between a fixed state in which the second rotating element is fixed to the transmission case and a reverse rotation preventing state in which the second rotating element is allowed to rotate forward and prevents reverse rotation. A way clutch can also be used. This also can reduce the friction loss and improve the shift controllability.

  [6] In the present invention, the four planetary gear mechanisms are so-called single pinion type planetary gear mechanisms comprising a sun gear, a ring gear, and a carrier that rotatably and revolves a pinion that meshes with the sun gear and the ring gear. Preferably there is.

  According to this, the planetary gear mechanism is a so-called double gear comprising a sun gear, a ring gear, and a carrier that rotatably supports and rotates a pair of pinions that mesh with each other and one meshes with the sun gear and the other meshes with the ring gear. Compared with the case of using a pinion type planetary gear mechanism, the number of gear meshes in the power transmission path from the input shaft to the output member can be reduced, and the transmission efficiency can be improved.

  [7] In the present invention, a start clutch that can transmit the power of the drive source to the input shaft may be provided.

  [8] In the present invention, the power of the drive source may be transmitted to the input shaft via a torque converter.

The skeleton figure of the embodiment of the automatic transmission of the present invention. The alignment chart of the planetary gear mechanism of embodiment. (A) is explanatory drawing which shows collectively the state of the engagement mechanism in each gear stage of embodiment. (B) is explanatory drawing which shows an example of the gear ratio of each gear stage of embodiment. (C) is explanatory drawing which shows an example of the common ratio of each gear stage of embodiment. (D) is explanatory drawing which shows an example of the gear ratio of each planetary gear mechanism of embodiment, and the reciprocal orange of an automatic transmission. Sectional drawing which shows an example of a 2 way clutch.

  FIG. 1 shows an upper half of an automatic transmission according to an embodiment of the present invention. The automatic transmission according to the present embodiment includes an input shaft 2 that is rotatably supported in a transmission case 1 and an output member 3 that includes an output gear that is disposed concentrically with the input shaft 2. The rotation of the output member 3 is transmitted to the left and right drive wheels of the vehicle via a differential gear and a propeller shaft (not shown).

  The input shaft 2 rotates by transmitting the power of the engine ENG as a drive source via the torque converter TC.

  The torque converter TC is a fluid torque converter that uses a fluid as a power transmission medium, and includes a lock-up clutch LC that can directly transmit power from the engine ENG to the input shaft 2. When the lockup clutch LC is engaged, the torque fluctuation of the engine ENG is transmitted to the input shaft 2. For this reason, the torsional damper device DA is provided so that the torque fluctuation of the engine ENG can be absorbed by the elastic force of the torsional damper device DA.

  In the transmission case 1, a first planetary gear mechanism PGS 1, a second planetary gear mechanism PGS 2, a third planetary gear mechanism PGS 3, and a fourth planetary gear mechanism PGS 4 are disposed concentrically with the input shaft 2.

  The first planetary gear mechanism PGS1 is a so-called single-pinion type planetary gear mechanism that includes a sun gear Sa, a ring gear Ra, and a carrier Ca that rotatably supports and rotates a pinion Pa that meshes with the sun gear Sa and the ring gear Ra. It is configured.

  Referring to the collinear diagram of the first planetary gear mechanism PGS1 shown in the upper part of FIG. 2 (the ratio of the relative rotational speeds of the respective elements can be represented by a straight line), the three elements Sa of the first planetary gear mechanism PGS1 are shown. , Ca, Ra are the first element, the second element, and the third element from the left side in the arrangement order at intervals corresponding to the gear ratio in the nomograph, respectively, the first element is the sun gear Sa, and the second element is the carrier Ca. The third element is the ring gear Ra.

  Here, the ratio between the distance between the sun gear Sa and the carrier Ca and the distance between the carrier Ca and the ring gear Ra is defined as h where the gear ratio of the first planetary gear mechanism PGS1 (number of teeth of the ring gear / number of teeth of the sun gear) is h. : 1 is set. In the alignment chart, the lower horizontal line and the upper horizontal line indicate that the rotational speeds are “0” and “1” (the same rotational speed as the input shaft 2), respectively.

  Similar to the first planetary gear mechanism PGS1, the fourth planetary gear mechanism PGS4 includes a sun gear Sd, a ring gear Rd, and a carrier Cd that rotatably and revolves a pinion Pd that meshes with the sun gear Sd and the ring gear Rd. This is a so-called single pinion type planetary gear mechanism.

  Referring to the collinear diagram of the fourth planetary gear mechanism PGS4 shown in the middle stage of FIG. 2, the three elements Sd, Cd, Rd of the fourth planetary gear mechanism PGS4 are arranged at intervals corresponding to the gear ratio in the collinear diagram. If the fourth element, the fifth element, and the sixth element are respectively arranged from the left in the order of arrangement, the fourth element is the sun gear Sd, the fifth element is the carrier Cd, and the sixth element is the ring gear Rd. The ratio between the distance between the sun gear Sd and the carrier Cd and the distance between the carrier Cd and the ring gear Rd is set to k: 1, where k is the gear ratio of the fourth planetary gear mechanism PGS4.

  Similar to the first and fourth planetary gear mechanisms PGS1 and PGS4, the second planetary gear mechanism PGS2 can freely rotate and revolve the sun gear Sb, the ring gear Rb, and the pinion Pb meshed with the sun gear Sb and the ring gear Rb. And a so-called single pinion type planetary gear mechanism comprising a carrier Cb pivotally supported on the shaft.

  The third planetary gear mechanism PGS3 is similar to the first, second, and fourth planetary gear mechanisms PGS1, PGS2, and PGS4, and the pinion Pc meshes with the sun gear Sc, the ring gear Rc, the sun gear Sc, and the ring gear Rc. Is constituted by a so-called single pinion type planetary gear mechanism comprising a carrier Cc that pivotally supports and rotates freely.

  Further, the carrier Cb of the PGS2 of the second planetary gear mechanism and the ring gear Rc of the third planetary gear mechanism PGS3 are connected, and the sun gear Sb of the PGS2 of the second planetary gear mechanism and the carrier Cc of the third planetary gear mechanism PGS3 are connected. Has been. Thereby, four rotation elements are comprised by the 2nd and 3rd planetary gear mechanism.

  Referring to the collinear diagram of the four rotating elements by the second and third planetary gear mechanisms shown in the lower part of FIG. 2, each rotating element is arranged from the left side in the order of arrangement at intervals corresponding to the gear ratio in the collinear diagram. Assuming that the first rotation element Y1, the second rotation element Y2, the third rotation element Y3, and the fourth rotation element Y4, the first rotation element Y1 is the ring gear Rb of the second planetary gear mechanism PGS2, and the second rotation element Y2 is the second rotation element Y2. The carrier Cb of the planetary gear mechanism PGS2, the ring gear Rc of the third planetary gear mechanism PGS3, the third rotating element Y3 is the sun gear Sb of the second planetary gear mechanism PGS2, the carrier Cc of the third planetary gear mechanism PGS3, and the fourth rotating element Y4 is It becomes the sun gear Sc of the third planetary gear mechanism PGS3.

  When the gear ratio of the second planetary gear mechanism PGS2 is i and the gear ratio of the third planetary gear mechanism PGS3 is j, the interval between the first to fourth rotating elements is a ratio of 1: i: ij. ing.

  The ring gear Ra (third element) of the first planetary gear mechanism PGS1 and the third rotation element Y3 are connected to form a first connection body Ra-Y3. Further, the carrier Cd (fifth element) of the fourth planetary gear mechanism PGS4 and the first rotating element Y1 are coupled to each other to form a second coupled body Cd-Y1. The sun gear Sa (first element) of the first planetary gear mechanism PGS <b> 1 is connected to the input shaft 2. The ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 is connected to the output member 3.

  The automatic transmission according to the present embodiment includes first to third brakes B1 to B3 and first to third clutches C1 to C3 as engagement mechanisms.

  The first brake B1 and the third brake B3 are constituted by wet multi-plate brakes, and the second brake B2 is constituted by a dog clutch as a meshing mechanism. The first clutch C1 is a dog clutch as a meshing mechanism, and the second clutch C2 and the third clutch C3 are wet multi-plate clutches.

  The first brake B1 is configured to be switchable between a fixed state in which the second coupling body Cd-Y1 is fixed to the transmission case 1 and an open state in which this fixing is released. The second brake B2 is configured to be switchable between a fixed state in which the second rotating element Y2 is fixed to the transmission case 1 and an open state in which this fixing is released. The third brake B3 is configured to be switchable between a fixed state in which the sun gear Sd (fourth element) of the fourth planetary gear mechanism PGS4 is fixed to the transmission case 1 and an open state in which this fixing is released.

  The first clutch C1 includes a connection state that connects the carrier Ca (second element) of the first planetary gear mechanism PGS1 and the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4, and an open state that disconnects this connection. It is configured to be switchable. The second clutch C2 is configured to be switchable between a connected state in which the sun gear Sa (first element) of the first planetary gear mechanism PGS1 and the second rotating element Y2 are connected and an open state in which this connection is broken. The third clutch C3 is configured to be switchable between a connected state in which the sun gear Sa (first element) of the first planetary gear mechanism PGS1 and the fourth rotating element Y4 are connected and an open state in which this connection is broken.

  The states of the engagement mechanisms B1 to B3 and C1 to C3 are switched by a transmission control unit (not shown).

  In the transmission case 1, the second clutch C 2, the third clutch C 3, the third planetary gear mechanism PGS 3, the first planetary gear mechanism PGS 1, The three brakes B3, the output member 3, the fourth planetary gear mechanism PGS4, and the first clutch C1 are arranged in this order.

  The second planetary gear mechanism PGS2 is disposed radially outward of the first planetary gear mechanism PGS1, and the ring gear Ra (third element) of the first planetary gear mechanism PGS1 and the sun gear of the second planetary gear mechanism PGS2. Sb is integrally formed. Thereby, since the first planetary gear mechanism PGS1 and the second planetary gear mechanism PGS2 overlap in the radial direction, the automatic operation is automatically performed compared to the case where the first planetary gear mechanism PGS1 and the second planetary gear mechanism PGS2 are arranged in the axial direction. The shaft length of the transmission can be shortened, and the mountability to a vehicle, particularly a so-called FF type vehicle can be improved.

  The first planetary gear mechanism PGS1 and the second planetary gear mechanism PGS2 only need to overlap at least partly in the radial direction, and this can reduce the axial length. If they overlap in the direction, the axial length can be shortened the most.

  A side wall 1a extending inward in the radial direction is provided in the transmission case 1 between the output member 3 and the third brake B3. The side wall 1 a is provided with a cylindrical portion 1 b that extends inward in the radial direction of the output member 3. The output member 3 is pivotally supported by the cylindrical portion 1b via a bearing. By configuring in this way, the output member 3 can be firmly supported by the cylindrical portion 1b having high mechanical strength connected to the transmission case 1.

  In the automatic transmission according to the present embodiment, when the first gear is established, the second brake B2 and the third brake B3 are set in a fixed state and the first clutch C1 is set in a connected state. By setting the second brake B2 in a fixed state, the rotation speed of the second rotation element Y2 becomes “0”. Further, by setting the third brake B3 in a fixed state, the rotational speed of the sun gear Sd (fourth element) of the fourth planetary gear mechanism PGS4 becomes “0”.

  Then, by bringing the first clutch C1 into the connected state, the carrier Ca (second element) of the first planetary gear mechanism PGS1 and the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 rotate at the same speed. . Then, the rotational speed of the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 connected to the output member 3 is “1st” shown in FIG. 2, and the first gear is established.

  When establishing the second gear, the first brake B1 and the second brake B2 are set in a fixed state, and the first clutch C1 is set in a connected state. By setting the first brake B1 and the second brake B2 to the fixed state, the rotation speeds of the first rotation element Y1 and the second rotation element Y2 are both “0”. For this reason, the first to fourth rotating elements Y1 to Y4 are in a locked state in which relative rotation is impossible, and the rotation speed of the first coupling body Ra-Y3 becomes “0”.

  Since the rotation speed of the sun gear Sa (first element) of the first planetary gear mechanism PGS1 connected to the input shaft 2 is “1”, the rotation of the carrier Ca (second element) of the first planetary gear mechanism PGS1. The speed is “1 / (h + 1)”. Further, by bringing the first clutch C1 into the connected state, the carrier Ca (second element) of the first planetary gear mechanism PGS1 and the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 rotate at the same speed. . Therefore, the rotational speed of the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 connected to the output member 3 is “1 / (h + 1)”, and the second gear is established.

  When establishing the third gear, the second brake B2 is set in a fixed state, and the first clutch C1 and the third clutch C3 are set in a connected state. By bringing the third clutch C3 into the connected state, the rotational speed of the fourth rotating element Y4 becomes “1”. Further, by setting the second brake B2 in a fixed state, the rotation speed of the second rotation element Y2 becomes “0”.

  Then, by bringing the first clutch C1 into the connected state, the carrier Ca (second element) of the first planetary gear mechanism PGS1 and the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 have the same speed. Therefore, the rotational speed of the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 connected to the output member 3 is “(h + j + 1) / {(h + 1) · (j + 1)}”. Is established.

  When establishing the fourth speed, the first brake B1 is set in a fixed state, and the first clutch C1 and the third clutch C3 are set in a connected state. By bringing the third clutch C3 into the connected state, the rotational speed of the fourth rotating element Y4 becomes “1”. Moreover, the rotational speed of 2nd coupling body Cd-Y1 will be set to "0" by making 1st brake B1 into a fixed state.

  Then, by bringing the first clutch C1 into the connected state, the carrier Ca (second element) of the first planetary gear mechanism PGS1 and the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 have the same speed. Therefore, the rotational speed of the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 connected to the output member 3 is “(hi + ij + h + i + 1) / (hij + hi + ij + h + i + 1)”, and the fourth speed stage is established.

  When establishing the fifth gear, the third brake B3 is set in a fixed state, and the first clutch C1 and the third clutch C3 are set in a connected state. By bringing the third clutch C3 into the connected state, the rotational speed of the fourth rotating element Y4 becomes “1”. Further, by setting the third brake B3 in a fixed state, the rotational speed of the sun gear Sd (fourth element) of the fourth planetary gear mechanism PGS4 becomes “0”.

  Then, by bringing the first clutch C1 into the connected state, the carrier Ca (second element) of the first planetary gear mechanism PGS1 and the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 have the same speed. Therefore, the rotational speed of the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 coupled to the output member 3 is “[{(h + 1) · (i + 1) + ij} · (k + 1)] / [{(h + 1 ) · (I + 1) + ij} · (k + 1) + hij] ”is established.

  When the sixth speed is established, the first clutch C1, the second clutch C2, and the third clutch C3 are brought into a connected state. By bringing the second clutch C2 and the third clutch C3 into the connected state, the rotation speeds of the second rotation element Y2 and the fourth rotation element Y4 become “1”. For this reason, the first to fourth rotating elements Y1 to Y4 are in a locked state in which relative rotation is impossible, and the rotation speed of the first coupling body Ra-Y3 is “1”.

  Since the rotation speed of the sun gear Sa (first element) of the first planetary gear mechanism PGS1 connected to the input shaft 2 is “1”, the first to third elements of the first planetary gear mechanism PGS1 Sa, Ca, Ra is in a locked state where relative rotation is impossible, and the first to third elements Sa, Ca, Ra rotate by “1”. Further, by bringing the first clutch C1 into the connected state, the carrier Ca (second element) of the first planetary gear mechanism PGS1 and the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 rotate at the same speed. . Therefore, the rotational speed of the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 connected to the output member 3 is “1”, and the sixth speed is established.

  When establishing the seventh gear, the third brake B3 is set in a fixed state, and the first clutch C1 and the second clutch C2 are set in a connected state. By setting the second clutch C2 to the connected state, the rotation speed of the second rotation element Y2 becomes “1”. Further, by setting the third brake B3 in a fixed state, the rotational speed of the sun gear Sd (fourth element) of the fourth planetary gear mechanism PGS4 becomes “0”.

  Then, by bringing the first clutch C1 into the connected state, the carrier Ca (second element) of the first planetary gear mechanism PGS1 and the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 have the same speed. Accordingly, the rotational speed of the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 connected to the output member 3 is “{(k + 1) · (hi + h + 1)} / {k · (hi + h + 1) + h + 1}”. Thus, the seventh gear is established.

  When establishing the eighth speed, the third brake B3 is set in a fixed state, and the second clutch C2 and the third clutch C3 are set in a connected state. By bringing the second clutch C2 and the third clutch C3 into the connected state, the rotation speeds of the second rotation element Y2 and the fourth rotation element Y4 become “1”. For this reason, the first to fourth rotating elements Y1 to Y4 are in a locked state in which relative rotation is impossible, and the rotation speed of the second coupling body Cd-Y1 is “1”.

  Then, by setting the third brake B3 in a fixed state, the rotational speed of the sun gear Sd (fourth element) of the fourth planetary gear mechanism PGS4 becomes “0”. Therefore, the rotational speed of the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 connected to the output member 3 is “(k + 1) / k”, and the eighth gear is established.

  When establishing the reverse gear, the second brake B2 and the third brake B3 are set in a fixed state, and the third clutch C3 is set in a connected state. By bringing the third clutch C3 into the connected state, the rotational speed of the fourth rotating element Y4 becomes “1”. Further, by setting the second brake B2 in a fixed state, the rotation speed of the second rotation element Y2 becomes “0”. For this reason, the rotational speed of the second coupled body Cd-Y1 is “−1 / {i · (j + 1)}” (note that minus indicates rotation in the reverse direction).

  Then, by setting the third brake B3 in a fixed state, the rotational speed of the sun gear Sd (fourth element) of the fourth planetary gear mechanism PGS4 becomes “0”. Therefore, the rotational speed of the ring gear Rd (sixth element) of the fourth planetary gear mechanism PGS4 connected to the output member 3 is “− (k + 1) / {ik · (j + 1)}”, and the reverse gear is established. Is done.

  A speed line indicated by a dotted line in FIG. 2 represents that each element of the other planetary gear mechanisms rotates following the planetary gear mechanism that transmits power among the four planetary gear mechanisms PGS1 to PGS4.

  FIG. 3A is a diagram summarizing and displaying the states of the first to third brakes B1 to B3 and the first to third clutches C1 to C3 in each of the above-described shift stages. “◯” in the columns of the first to third brakes B1 to B3 and the first to third clutches C1 to C3 represents a fixed state or a connected state.

  3 (b), the gear ratio h of the first planetary gear mechanism PGS1 is 2.043, the gear ratio i of the second planetary gear mechanism PGS2 is 1.371, as shown in FIG. 3 (d). Gear ratios of the respective speeds when the gear ratio j of the three planetary gear mechanism PGS3 is 3.181 and the gear ratio k of the fourth planetary gear mechanism PGS4 is 1.725 (the rotational speed of the input shaft 2 / the rotation of the output member 3). Speed). According to this, the common ratio (ratio of gear ratios between the gears) shown in FIG. 3 (c) becomes appropriate, and the ratio orange (gear ratio of 1st speed / 8th gear stage) shown in FIG. 3 (d) is obtained. The gear ratio) is also appropriate.

  According to the automatic transmission of the present embodiment, it is possible to perform eight forward speeds and one reverse speed. In addition, the number of engagement mechanisms that generate friction loss at each shift stage is three, and the engagement mechanisms that are open at four shift mechanisms at each shift stage are open compared to the conventional mechanism that generates friction loss. The friction loss due to the combined mechanism can be reduced, and the transmission efficiency of the automatic transmission is improved.

  In this embodiment, since the second brake B2 of the present invention is constituted by a dog clutch that is a meshing mechanism, the second brake B2 is in an open state as compared with the case where the second brake B2 is constituted by a wet multi-plate brake. No friction loss occurs in the dog clutch, which is the second brake B2, at the fourth to eighth gears. For this reason, the friction loss can be further reduced as the entire automatic transmission.

  In the present embodiment, since the first clutch C1 of the present invention is constituted by a dog clutch that is a meshing mechanism, the first clutch C1 has a friction loss compared to the case where the first clutch C1 is constituted by a wet multi-plate clutch. In the 8th speed and the reverse speed that are in the released state, there is no friction loss in the dog clutch as the first clutch C1. For this reason, the friction loss can be further reduced as the entire automatic transmission.

  In the present embodiment, the first to fourth planetary gear mechanisms PGS1 to PGS4 are constituted by so-called single pinion type planetary gear mechanisms. Therefore, the first to fourth planetary gear mechanisms PGS1 to PGS4 are engaged with the sun gear and the ring gear, and a pair of pinions, one of which engages with the sun gear and the other of which engages with the ring gear, can rotate and revolve. Compared to a so-called double pinion type planetary gear mechanism composed of a supporting carrier, the number of meshing gears can be reduced, and transmission efficiency can be improved.

  In the present embodiment, a dog clutch is used as the second brake B2. However, the present invention is not limited to this, and the second brake B2 may be configured by a synchromesh mechanism that is a meshing mechanism having a synchronization function. Also by this, a friction loss can be suppressed compared with the case where it comprises a wet multi-plate clutch.

  Further, even if the second brake B2 is constituted by a wet multi-plate clutch, it is possible to obtain the effect of the present invention that the number of releases at each shift stage can be three or less.

  In the present embodiment, a dog clutch is used as the first clutch C1. However, the present invention is not limited to this, and the first clutch C1 may be a synchromesh mechanism that is a meshing mechanism having a synchronization function. Also by this, a friction loss can be suppressed compared with the case where it comprises a wet multi-plate clutch.

  Even if the first clutch C1 is a wet multi-plate clutch, it is possible to obtain the effect of the present invention that the number of releases at each gear stage can be three or less.

  In the first embodiment, the second brake B2 is in a fixed state in which the second rotating element Y2 is fixed to the transmission case 1 and in a reverse rotation preventing state in which the second rotating element Y2 is allowed to rotate forward and reverse rotation is prevented. Alternatively, a two-way clutch that can be switched between is possible. An example of the two-way clutch will be specifically described with reference to FIG.

  The two-way clutch TW as the second brake B2 in FIG. 4 is disposed with an inner ring TW1 coupled to the second rotating element Y2 and a radial outer side of the inner ring TW1 with a gap therebetween, and a transmission case 1 is provided with an outer ring TW2 connected to 1, and a holding ring TW3 disposed between the inner ring TW1 and the outer ring TW2.

  A plurality of cam surfaces TW1a are formed on the outer peripheral surface of the inner ring TW1. The retaining ring TW3 is provided with a plurality of cutout holes TW3a corresponding to the cam surface TW1a. A roller TW4 is accommodated in the cutout hole TW3a. The two-way clutch TW includes a first electromagnetic clutch and a second electromagnetic clutch that are not shown.

  The first electromagnetic clutch is configured to connect the outer ring TW2 and the holding ring TW3 when energized. When the first electromagnetic clutch is not energized, the holding ring TW3 is configured to be rotatable relative to the inner ring TW1 and the outer ring TW2.

  Further, as shown in FIG. 4B, the second electromagnetic clutch has a first state in which the retaining ring TW3 is connected to the inner ring TW1 in a state where the notch hole TW3a is located at one end of the cam surface TW1a. 4C, a second state in which the retaining ring TW3 is coupled to the inner ring TW1 in a state where the cutout hole TW3a is located at the other end of the cam surface TW1a, and the retaining ring TW3 and the inner ring TW1. It is configured to be switchable to a third state in which the connection with is disconnected.

  Further, as shown in FIG. 4A, the diameter of the roller TW4 is such that when the roller TW4 is present at the center of the cam surface TW1a, a gap A is opened, and as shown in FIGS. 4B and 4C, When the roller TW4 is at the end of the cam surface TW1a, the roller TW4 is set to contact the inner ring TW1 and the outer ring TW2.

  When the first electromagnetic clutch is energized, the holding ring TW3 is fixed to the transmission case 1 via the outer ring TW2. In this case, regardless of whether the inner ring TW1 is rotated forward or backward, the holding ring TW3 is fixed as shown in FIGS. 4B and 4C, so that the roller TW4 is positioned on the cam surface TW1a. It will be located at the end. At this time, the roller TW4 is sandwiched between the cam surface TW1a and the inner peripheral surface of the outer ring TW2, and the rotation of the inner ring TW1 is prevented. That is, the two-way clutch TW is in a fixed state.

  When the first electromagnetic clutch is not energized, the holding ring TW3 can freely rotate, so that the roller TW4 continues to be positioned at the center of the cam surface TW1a as shown in FIG. be able to. Therefore, when the first electromagnetic clutch is not energized, the inner ring TW1 can freely rotate. If the clockwise direction in FIG. 4 is the reverse direction, the two-way clutch TW does not energize the first electromagnetic clutch, disconnects the outer ring TW2 and the holding ring TW3, and the inner ring TW1 rotates freely. By setting the second electromagnetic clutch in the first state, the reverse rotation preventing state can be obtained.

  As described above, the two-way clutch TW that can be switched between the fixed state and the reverse rotation prevention state can be configured.

  When the second brake B2 is configured with such a 2-way clutch TW, the 2-way clutch TW is set in the reverse rotation prevention state at the forward speed from the fourth speed to the eighth speed, and from the first speed to the third speed. Each shift stage can be established by fixing the forward and reverse speeds. In this case, if the upshift to the fourth speed is predicted based on the vehicle information such as the traveling speed while traveling at the third speed, the transmission control unit (not shown) is used as the second brake B2. Preferably, the two-way clutch TW is switched to the reverse rotation prevention state in advance.

  According to this, when upshifting from the third gear to the fourth gear, the switching of the state of the two-way clutch TW as the second brake B2 is completed, and only the first brake B1 is brought into the connected state. Since the speed can be changed to the fourth speed, the upshift from the third speed to the fourth speed can be performed smoothly. Therefore, the shift controllability of the automatic transmission is improved when the second brake B2 is configured with the two-way clutch TW, compared with the second brake B2 configured with a dog clutch.

  If the second brake B2 is configured by the two-way clutch TW described above, unlike the case where the second brake B2 is configured by a friction engagement type brake, no friction loss occurs in the second brake B2. Accordingly, as in the case where the second brake B2 is configured by a meshing mechanism, the friction loss can be suppressed as the whole automatic transmission.

  Further, the two-way clutch TW as the second brake B2 includes a reverse rotation preventing state in which the second rotation element Y2 is allowed to rotate forward and reverse rotation is prevented in addition to the above-described fixed state and reverse rotation preventing state, The rotation element Y2 may be configured to be switchable to a forward rotation prevention state in which forward rotation of the rotation element Y2 is prevented and reverse rotation is allowed. In the above-described 2-way clutch TW, the first electromagnetic clutch is not energized, the inner ring TW1 is allowed to rotate freely, and the second electromagnetic clutch is set to the second state, thereby preventing forward rotation. It becomes a state.

  Further, in the automatic transmission according to the present embodiment, eight forward speeds and one reverse speed can be established. For example, the second speed and the third speed are omitted, and the sixth forward speed and the first reverse speed are set. It is good also as an automatic transmission which can establish this gear stage. Also in this case, it is possible to obtain the effect of the present invention that the number of releases at each shift stage can be three or less.

  In this embodiment, the power of the engine ENG is transmitted to the input shaft 2 via the torque converter TC. However, instead of the torque converter TC, a single-plate type or a power-transmittable power by engagement with a friction plate A multi-plate start clutch may be used.

  DESCRIPTION OF SYMBOLS 1 ... Transmission case, 2 ... Input shaft, 3 ... Output member, ENG ... Engine (drive source), TC ... Torque converter, DA ... Torsional damper device, LC ... Lock-up clutch, PGS1 ... First planetary gear mechanism, Sa ... Sun gear (first element), Ca ... carrier (second element), Ra ... ring gear (third element), Pa ... pinion, PGS2 ... second planetary gear mechanism, Sb ... sun gear, Cb ... carrier, Rb ... ring gear, Pb ... pinion, PGS3 ... third planetary gear mechanism, Sc ... sun gear, Cc ... carrier, Rc ... ring gear, Pc ... pinion, PGS4 ... fourth planetary gear mechanism, Sd ... sun gear (fourth element), Cd ... carrier (first) 5 elements), Rd ... ring gear (sixth element), Pd ... pinion, Y1-Y4 ... first to fourth rotating elements, B1-B3 ... first to third brakes, C1- 3 ... first to third clutches, TW ... 2-way clutches.

Claims (8)

An automatic transmission that is rotatably supported in a transmission case and includes an input shaft that is rotated by transmission of power from a drive source, and that rotates the input shaft in multiple stages and outputs it from an output member. There,
There are provided first to fourth planetary gear mechanisms each having three elements including a sun gear, a carrier, and a ring gear,
The three elements of the first planetary gear mechanism are a first element, a second element, and a third element, respectively, in the order of arrangement at intervals corresponding to the gear ratio in the collinear chart in which the relative rotational speed ratio can be represented by a straight line. ,
The three elements of the fourth planetary gear mechanism are a fourth element, a fifth element, and a sixth element, respectively, in the order of arrangement at intervals corresponding to the gear ratio in the collinear diagram,
Each of the elements of the second planetary gear mechanism and the third planetary gear mechanism constitutes four rotating elements, and the four rotating elements are arranged in the alignment order in the collinear diagram, respectively, the first rotating element, the second rotating element, As the third rotating element and the fourth rotating element,
The first element is configured by connecting the third element and the third rotating element, and the second element is configured by connecting the fifth element and the first rotating element,
The first element is connected to the input shaft, the sixth element is connected to the output member;
As an engagement mechanism,
A first brake capable of fixing the second connector to the transmission case;
A second brake capable of fixing the second rotating element to the transmission case;
A third brake capable of fixing the fourth element to the transmission case;
A first clutch capable of connecting the second element and the sixth element;
A second clutch capable of connecting the first element and the second rotating element;
A third clutch capable of connecting the first element and the fourth rotating element;
By bringing at least three engagement mechanisms out of a total of six engagement mechanisms including the first to third brakes and the first to third clutches into a connected state or a fixed state, An automatic transmission characterized by establishing each gear position.   2. The automatic transmission according to claim 1, wherein the second planetary gear mechanism is disposed radially outward of the first planetary gear mechanism, and the ring gear of the first planetary gear mechanism and the second planetary gear mechanism An automatic transmission characterized by being integrally formed with a sun gear.   The automatic transmission according to claim 1 or 2, wherein the second brake is constituted by a meshing mechanism.   4. The automatic transmission according to claim 1, wherein the first clutch includes a meshing mechanism. 5.   3. The automatic transmission according to claim 1, wherein the second brake permits a fixed state in which the second rotating element is fixed to a transmission case, and allows the second rotating element to rotate forward and reversely rotate. 2. An automatic transmission comprising a two-way clutch that can be switched between a reverse rotation preventing state and a blocking state.   6. The automatic transmission according to claim 1, wherein the four planetary gear mechanisms include a sun gear, a ring gear, and a pinion that meshes with the sun gear and the ring gear so as to rotate and revolve freely. 1. An automatic transmission characterized by being a single pinion type planetary gear mechanism comprising a supporting carrier.   The automatic transmission according to any one of claims 1 to 6, further comprising a starting clutch capable of transmitting the power of the driving source to the input shaft.   The automatic transmission according to any one of claims 1 to 6, wherein the power of the drive source is transmitted to the input shaft through a torque converter.

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