JP5379106B2 - 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 in which the speed ratio can be represented by a straight line at intervals corresponding to the gear ratio in the alignment chart, and the three elements of the second planetary gear mechanism are aligned. The fourth element, the fifth element, and the sixth element are arranged in the order corresponding to the gear ratio in the drawing, respectively, and the three elements of the third planetary gear mechanism are arranged in the interval corresponding to the gear ratio in the alignment chart. 7th element, 8th element and 9th element in order The three elements of the fourth planetary gear mechanism are divided into the tenth element, the eleventh element, and the twelfth element in the arrangement order at intervals corresponding to the gear ratio in the collinear diagram, respectively, and the second element and the sixth element Are connected to form a first connecting body, the third element and the eighth element are connected to form a second connecting body, and the fifth element and the eleventh element are connected to form a third connecting body. The seventh element and the twelfth element are connected to form a fourth connecting body, the first element is connected to the input shaft, the tenth element is connected to the output member, and the fourth element is used as an engagement mechanism. A first brake that can be fixed to the transmission case, a second brake that can fix the ninth element to the transmission case, a third brake that can fix the second coupling body to the transmission case, and a third coupling body. A fourth brake that can be fixed to the transmission case, a first element that can connect the first element and the third connector. A latch, a second clutch capable of coupling the first coupling body and the fourth coupling body, and a total of six engagements of the first to fourth brakes and the first and second clutches; Each shift stage is established by bringing at least three engagement mechanisms of the combined mechanism into a connected state or a fixed state.

  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 four brakes and two clutches, 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 seventh element is the ring gear of the third planetary gear mechanism, the twelfth element is the sun gear of the fourth planetary gear mechanism, and the fourth planetary gear mechanism is radially outward of the third planetary gear mechanism. Preferably, the ring gear of the third planetary gear mechanism and the sun gear of the fourth planetary gear mechanism are integrally configured.

  According to this, since the fourth planetary gear mechanism is arranged radially outward of the third 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 first brake is constituted by a meshing mechanism. Accordingly, it is possible to suppress the friction loss at the meshing mechanism serving as the first brake at the gear position where the first brake is in the released state. 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 fourth brake is constituted by a meshing mechanism. Accordingly, it is possible to suppress the friction loss at the meshing mechanism serving as the fourth brake at the shift speed at which the fourth brake is released. For this reason, the friction loss can be further reduced as the entire automatic transmission.

  [5] In the present invention, the fourth brake can be switched between a fixed state in which the third connecting body is fixed to the transmission case and a reverse rotation preventing state in which the third connecting body 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 a collinear diagram of the first planetary gear mechanism PGS1 shown in the uppermost stage of FIG. 2 (a diagram in which the ratio of the relative rotational speeds of the respective elements can be represented by a straight line), the three elements of the first planetary gear mechanism PGS1 Assuming Sa, Ca, Ra as the first element, the second element, and the third element from the left side in the order of arrangement 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 PGS1, the second planetary gear mechanism PGS2 includes a sun gear Sb, a ring gear Rb, and a carrier Cb that rotatably and revolves a pinion Pb that meshes with the sun gear Sb and the ring gear Rb. It is constituted by a so-called single pinion type planetary gear mechanism.

  Referring to the collinear diagram of the second planetary gear mechanism PGS2 shown in the second stage from the top in FIG. 2, the three elements Sb, Cb, Rb of the second planetary gear mechanism PGS2 correspond to the gear ratios in the collinear diagram. Assuming that the fourth element, the fifth element, and the sixth element are arranged from the left side in the order in which they are arranged, the fourth element is the sun gear Sb, the fifth element is the carrier Cb, and the sixth element is the ring gear Rb. The ratio between the distance between the sun gear Sb and the carrier Cb and the distance between the carrier Cb and the ring gear Rb is set to i: 1, where i is the gear ratio of the second planetary gear mechanism PGS2.

  Similarly to the first and second planetary gear mechanisms PGS1 and PGS2, the third planetary gear mechanism PGS3 supports the sun gear Sc, the ring gear Rc, and the pinion Pc meshing with the sun gear Sc and the ring gear Rc so as to freely rotate and revolve. And a so-called single pinion type planetary gear mechanism comprising a carrier Cc.

  With reference to the collinear diagram of the third planetary gear mechanism PGS3 shown in the third stage from the top in FIG. 2, the three elements Sc, Cc, Rc of the third planetary gear mechanism PGS3 correspond to the gear ratios in the collinear diagram. Assuming that the seventh element, the eighth element, and the ninth element are arranged from the left side in the order in which they are arranged, the seventh element is the ring gear Rc, the eighth element is the carrier Cc, and the ninth element is the sun gear Sc. The ratio between the distance between the sun gear Sc and the carrier Cc and the distance between the carrier Cc and the ring gear Rc is set to j: 1, where j is the gear ratio of the third planetary gear mechanism PGS3.

  The fourth planetary gear mechanism PGS4, like the first to third planetary gear mechanisms PGS1 to PGS3, supports the sun gear Sd, the ring gear Rd, and the pinion Pd that meshes with the sun gear Sd and the ring gear Rd so as to freely rotate and revolve. And a so-called single pinion type planetary gear mechanism comprising a carrier Cd.

  Referring to the collinear diagram of the fourth planetary gear mechanism PGS4 shown in the lowermost stage (fourth stage from the top) in FIG. 2, the three elements Sd, Cd, Rd of the fourth planetary gear mechanism PGS4 are If the tenth element, the eleventh element, and the twelfth element are arranged from the left in the order of arrangement at intervals corresponding to the gear ratio, the tenth element is the ring gear Rd, the eleventh element is the carrier Cd, and the twelfth element is the sun gear Sd. 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.

  The carrier Ca (second element) of the first planetary gear mechanism PGS1 and the ring gear Rb (sixth element) of the second planetary gear mechanism PGS2 are coupled to form a first coupled body Ca-Rb. Further, the ring gear Ra (third element) of the first planetary gear mechanism PGS1 and the carrier Cc (eighth element) of the third planetary gear mechanism PGS3 are connected to form a second connected body Ra-Cc.

  Further, the carrier Cb (fifth element) of the second planetary gear mechanism PGS2 and the carrier Cd (eleventh element) of the fourth planetary gear mechanism PGS4 are coupled to constitute a third coupled body Cb-Cd. Further, the ring gear Rc (seventh element) of the third planetary gear mechanism PGS3 and the sun gear Sd (12th element) of the fourth planetary gear mechanism PGS4 are connected to constitute a fourth connecting body Rc-Sd. 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 (tenth 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 fourth four brakes B1 to B4 and first and second two clutches C1 and C2 as engagement mechanisms.

  1st brake B1 and 4th brake B4 are comprised by the dog clutch as a meshing mechanism, and 2nd brake B2 and 3rd brake B3 are comprised by the wet multi-plate brake. The first clutch C1 and the second clutch C2 are wet multi-plate clutches.

  The first brake B1 is configured to be switchable between a fixed state in which the sun gear Sb (fourth element) of the second planetary gear mechanism PGS2 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 sun gear Sc (9th element) of the third planetary gear mechanism PGS3 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 second coupling body Ra-Cc is fixed to the transmission case 1 and an open state in which this fixing is released. The fourth brake B4 is configured to be switchable between a fixed state in which the third coupling body Cb-Cd is fixed to the transmission case 1 and an open state in which this fixing is released.

  The first clutch C1 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 third connected body Cb-Cd are connected, and an open state in which the connection is broken. Yes. The second clutch C2 is configured to be switchable between a connection state in which the first connection body Ca-Rb and the fourth connection body Rc-Sd are connected and an open state in which the connection is broken.

  The states of the engagement mechanisms B1 to B4, C1, and C2 are switched by a transmission control unit (not shown).

  In the transmission case 1, the first brake B 1, the second planetary gear mechanism PGS 2, the first clutch C 1, the first planetary gear mechanism PGS 1, The second clutch C2, the third planetary gear mechanism PGS3, the output member 3, the third brake B3, and the second brake B2 are arranged in this order.

  The fourth planetary gear mechanism PGS4 is disposed radially outward of the third planetary gear mechanism PGS3, and the ring gear Rc (seventh element) of the third planetary gear mechanism PGS3 and the sun gear of the fourth planetary gear mechanism PGS4. Sd (the twelfth element) is integrally formed to constitute a fourth connector Rc-Sd. As a result, the third planetary gear mechanism PGS3 and the fourth planetary gear mechanism PGS4 overlap in the radial direction. Therefore, the third planetary gear mechanism PGS3 and the fourth planetary gear mechanism PGS4 are automatically compared with the case where they 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 third planetary gear mechanism PGS3 and the fourth planetary gear mechanism PGS4 only have to overlap at least partially in the radial direction, which can reduce the axial length. If they overlap in the direction, the axial length can be shortened the most.

  Also, with the above configuration, the first to third brakes B1 to B3 are disposed at both ends on the axis of the input shaft 2 in the transmission case 1, and the planetary gear mechanism and the clutch are obstructed. In other words, the degree of freedom in designing the oil passage for the brake is improved.

  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 first brake B1, the second brake B2, and the fourth brake B4 are set in a fixed state. By setting the first brake B1 in the fixed state, the rotational speed of the sun gear Sb (fourth element) of the second planetary gear mechanism PGS2 becomes “0”. Further, by setting the fourth brake B4 in a fixed state, the rotation speed of the third coupling body Cb-Cd becomes “0”.

  Accordingly, since the rotational speeds of the sun gear Sb (fourth element) of the second planetary gear mechanism PGS2 and the carrier Cb (fifth element) of the second planetary gear mechanism PGS2 are both “0”, the second planetary gear mechanism PGS2 The fourth to sixth elements Sb, Cb, Rb are in a locked state in which relative rotation is impossible, and the rotation speeds of the fourth to sixth elements Sb, Cb, Rb become “0”. And the rotational speed of 1st coupling body Ca-Rb also becomes "0".

  Since the rotational speed of the sun gear Sa (first element) of the first planetary gear mechanism PGS1 connected to the input shaft 2 is “1”, the rotational speed of the second coupled body Ra-Cc is “−1 / h. (Note that minus indicates rotation in the reverse direction).

  Further, by setting the second brake B2 in a fixed state, the rotational speed of the sun gear Sc (9th element) of the third planetary gear mechanism PGS3 becomes “0”, and the rotational speed of the fourth coupled body Rc-Sd becomes “− (J + 1) / (hj) ".

  Therefore, the rotational speed of the ring gear Rd (tenth element) of the fourth planetary gear mechanism PGS4 connected to the output member 3 becomes “(j + 1) / (hjk)”, and the first gear is established.

  When establishing the second gear, the first brake B1, the second brake B2, and the third brake B3 are set in a fixed state. By setting the third brake B3 to the fixed state, the rotation speed of the second coupling body Ra-Cc becomes “0”. Since the rotational speed of the sun gear Sa (first element) of the first planetary gear mechanism PGS1 coupled to the input shaft 2 is “1”, the rotational speed of the first coupled body Ca-Rb is “1 / (h + 1)”. It becomes.

  Then, by setting the first brake B1 in the fixed state, the rotational speed of the sun gear Sb (fourth element) of the second planetary gear mechanism PGS2 becomes “0”, and the rotational speed of the third coupled body Cb-Cd becomes “i”. / {(H + 1) · (i + 1)} ”.

  Further, by setting the second brake B2 to the fixed state, the rotational speed of the sun gear Sc (9th element) of the third planetary gear mechanism PGS3 becomes “0”, and the carrier Cc (8th element) of the third planetary gear mechanism PGS3. ) And the sun gear Sc (9th element) of the third planetary gear mechanism PGS3 are both “0”, so the seventh to ninth elements Rc, Cc, Sc of the third planetary gear mechanism PGS3 Is in a locked state where relative rotation is impossible, and the rotation speeds of the seventh to ninth elements Rc, Cc, Sc become “0”. The rotational speed of the fourth connector Rc-Sd is also “0”.

  Therefore, the rotational speed of the ring gear Rd (tenth element) of the fourth planetary gear mechanism PGS4 connected to the output member 3 is “i · (k + 1) / {(h + 1) · (i + 1) · k}”. Second gear is established.

  When establishing the third gear, the first brake B1 and the second brake B2 are set in a fixed state, and the second clutch C2 is set in a connected state. By setting the second clutch C2 to the connected state, the rotation speeds of the first connected body Ca-Rb and the fourth connected body Rc-Sd become the same.

  In this case, the sun gear Sa (first element) of the first planetary gear mechanism PGS1 is the first rotating element Y1, the first connecting body Ca-Rb and the fourth connecting body Rc-Sd are the second rotating element Y2, and the second rotating element Y2. When the connecting body Ra-Cc is the third rotating element Y3 and the sun gear Sc (the ninth element) of the third planetary gear mechanism PGS3 is the fourth rotating element Y4, the ratio of the rotational speeds of the four rotating elements Y1 to Y4 is shared. It can be represented by a straight line on the diagram.

  At this time, the interval between the first rotating element Y1 and the second rotating element Y2, the interval between the second rotating element Y2 and the third rotating element Y3, and the interval between the third rotating element Y3 and the fourth rotating element Y4 are: It is represented by “h: 1: j”.

  Then, by setting the second brake B2 in a fixed state, the rotational speed of the sun gear Sc (the ninth element) of the third planetary gear mechanism PGS3 becomes “0”. Since the rotational speed of the sun gear Sa (first element) of the first planetary gear mechanism PGS1 coupled to the input shaft 2 is “1”, the rotational speeds of the first coupled body Ca-Rb and the fourth coupled body Rc-Sd. Becomes “(j + 1) / (h + j + 1)”.

  Then, by setting the first brake B1 in the fixed state, the rotational speed of the sun gear Sb (fourth element) of the second planetary gear mechanism PGS2 becomes “0”, and the rotational speed of the third coupled body Cb-Cd becomes “i”. (J + 1) / {(i + 1) · (h + j + 1)} ”. Therefore, the rotational speed of the ring gear Rd (tenth element) of the fourth planetary gear mechanism PGS4 coupled to the output member 3 is “{(ik−1) · (j + 1)} / {(i + 1) · (h + j + 1) · k } "And the third gear is established.

  When establishing the fourth speed, 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 in the fixed state, the rotational speed of the sun gear Sb (fourth element) of the second planetary gear mechanism PGS2 becomes “0”. Moreover, the rotational speed of 3rd coupling body Cb-Cd will be set to "1" by making the 1st clutch C1 into a connection state. For this reason, the rotational speed of 1st coupling body Ca-Rb will be "(i + 1) / i".

  Since the rotational speed of the sun gear Sa (first element) of the first planetary gear mechanism PGS1 connected to the input shaft 2 is “1”, the rotational speed of the second coupled body Ra-Cc is “(hi + h + 1) / (Hi) ". Then, by setting the second brake B2 in a fixed state, the rotational speed of the sun gear Sc (the ninth element) of the third planetary gear mechanism PGS3 becomes “0”. For this reason, the rotational speed of the fourth coupled body Rc-Sd is “{(j + 1) · (hi + h + 1)} / (hij)”.

  Therefore, the rotational speed of the ring gear Rd (tenth element) of the fourth planetary gear mechanism PGS4 connected to the output member 3 becomes “{hijk− (hi + hj + h + j + 1)} / (hijk)”, and the fourth speed stage is established. The

  When establishing the fifth gear, the first brake B1 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 first brake B1 in the fixed state, the rotational speed of the sun gear Sb (fourth element) of the second planetary gear mechanism PGS2 becomes “0”. And the rotational speed of 3rd coupling body Cb-Cd will be "1" by making the 1st clutch C1 into a connection state. For this reason, the rotational speed of 1st coupling body Ca-Rb will be "(i + 1) / i".

  The 4th coupling body Rc-Sd rotates at the same speed as 1st coupling body Ca-Rb by making the 2nd clutch C2 into a connection state. Accordingly, the rotational speed of the ring gear Rd (tenth element) of the fourth planetary gear mechanism PGS4 connected to the output member 3 becomes “{i · (k + 1) − (i + 1)} / (ik)”, and the fifth speed A stage is established.

  When establishing the sixth gear, the second brake B2 is set in a fixed state, and the first clutch C1 and the second clutch C2 are set in a connected state. As in the case of establishing the third gear, the second brake B2 is fixed, and the second clutch C2 is connected to rotate the first connected body Ca-Rb and the fourth connected body Rc-Sd. The speed is “(j + 1) / (h + j + 1)”.

  Moreover, the rotational speed of 3rd coupling body Cb-Cd will be set to "1" by making the 1st clutch C1 into a connection state. Therefore, the rotational speed of the ring gear Rd (tenth element) of the fourth planetary gear mechanism PGS4 connected to the output member 3 is “{h · (k + 1) + k · (j + 1)} / {k · (h + j + 1)}”. Thus, the sixth gear 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 third brake B3 to the fixed state, the rotation speed of the second coupling body Ra-Cc becomes “0”. Since the rotational speed of the sun gear Sa (first element) of the first planetary gear mechanism PGS1 coupled to the input shaft 2 is “1”, the rotational speed of the first coupled body Ca-Rb is “1 / (h + 1). ) ”.

  Then, by bringing the first clutch C1 into the connected state, the rotational speed of the third connected body Cb-Cd becomes “1”, and by bringing the second clutch C2 into the connected state, the fourth connected body Rc-Sd becomes It rotates at the same speed as 1st coupling body Ca-Rb. Accordingly, the rotational speed of the ring gear Rd (tenth element) of the fourth planetary gear mechanism PGS4 connected to the output member 3 becomes “{h · (k + 1) + k} / {(h + 1) · k}”, and 7 A speed is established.

  When establishing the eighth speed, 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 rotational speed of the sun gear Sc (the ninth element) of the third planetary gear mechanism PGS3 becomes “0”. Further, by setting the third brake B3 in a fixed state, the rotational speed of the carrier Cc (eighth element) of the third planetary gear mechanism PGS3 becomes “0”.

  For this reason, since the rotational speeds of the carrier Cc (eighth element) of the third planetary gear mechanism PGS3 and the sun gear Sc (9th element) of the third planetary gear mechanism PGS3 are both “0”, the third planetary gear mechanism The seventh to ninth elements Rc, Cc, Sc of the PGS3 are in a locked state where relative rotation is impossible, and the rotation speeds of the seventh to ninth elements Rc, Cc, Sc become “0”. The rotational speed of the fourth connector Rc-Sd is also “0”.

  Moreover, the rotational speed of 3rd coupling body Cb-Cd will be set to "1" by making the 1st clutch C1 into a connection state. Accordingly, the rotational speed of the ring gear Rd (tenth 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 fourth brake B4 are set in a fixed state, and the second clutch C2 is set in a connected state. As in the case where the third speed and the sixth speed are established by setting the second brake B2 in the fixed state and the second clutch C2 in the connected state, the first connected body Ca-Rb and the fourth connected body Rc are used. The rotational speed of −Sd is “(j + 1) / (h + j + 1)”.

  And the rotation speed of 3rd coupling body Cb-Cd will be set to "0" by making 4th brake B4 into a fixed state. Therefore, the rotational speed of the ring gear Rd (tenth element) of the fourth planetary gear mechanism PGS4 connected to the output member 3 becomes “− (j + 1) / {k · (h + j + 1)}”, and the reverse gear is established. The

  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 fourth brakes B1 to B4 and the first and second two clutches C1 and C2 in each of the above-described shift stages. “◯” in the columns of the first to fourth brakes B1 to B4 and the first and second two clutches C1 and C2 indicate a fixed state or a connected state.

  3 (b), the gear ratio h of the first planetary gear mechanism PGS1 is 2.876, the gear ratio i of the second planetary gear mechanism PGS2 is 3.684th, as shown in FIG. 3 (d). The gear ratio of each gear stage (the rotational speed of the input shaft 2 / the rotation of the output member 3) when the gear ratio j of the three planetary gear mechanism PGS3 is 3.655 and the gear ratio k of the fourth planetary gear mechanism PGS4 is 2.321. 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.

  Further, in this embodiment, since the first brake B1 of the present invention is configured by a dog clutch that is a meshing mechanism, the first brake B1 is in an open state as compared with the case where the first brake B1 is configured by a wet multi-plate brake. From the 6th gear to the 8th gear and the reverse gear, there is no friction loss in the dog clutch as the first brake B1. For this reason, the friction loss can be further reduced as the entire automatic transmission.

  In this embodiment, since the fourth brake B4 of the present invention is configured by a dog clutch that is a meshing mechanism, the fourth brake B4 has a friction loss compared to the case where the fourth brake B4 is configured by a wet multi-plate brake. In the 2nd speed to 8th speed, which is the generated release state, no friction loss occurs in the dog clutch as the fourth brake B4. 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 can freely rotate and revolve a pair of pinions meshing with the sun gear and the ring gear, one meshing with the sun gear and the other meshing with the ring gear. Compared to a so-called double pinion type planetary gear mechanism composed of a carrier that supports the shaft, 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 first brake B1 or the fourth brake B4. However, the present invention is not limited to this, and the first brake B1 or the fourth brake B4 is a synchromesh mechanism that is a meshing mechanism having a synchronization function. You may comprise. Also by this, a friction loss can be suppressed compared with the case where a wet multi-plate brake is used.

  Further, even if the first brake B1 or the fourth brake B4 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 gear stage can be made three or less.

  In the present embodiment, the fourth planetary gear mechanism PGS4 is disposed radially outward of the third planetary gear mechanism PGS3. However, the present invention is not limited to this, and the third planetary gear mechanism PGS3 and the fourth planetary gear mechanism PGS4 are provided. They may be arranged side by side in the axial direction.

  In the first embodiment, the fourth brake B4 is fixed in a state in which the third connecting member Cb-Cd is fixed to the transmission case 1, and the forward rotation of the third connecting member Cb-Cd is allowed and the reverse rotation is prevented. You may comprise with the 2 way clutch switchable to a reverse rotation prevention state. An example of the two-way clutch will be specifically described with reference to FIG.

  The two-way clutch TW as the fourth brake B4 in FIG. 4 is arranged with an inner ring TW1 coupled to the third coupling body Cb-Cd and a radially outer side of the inner ring TW1 with a space therebetween, and the speed is changed. An outer ring TW2 connected to the machine case 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 4th brake B4 is configured by such a 2-way clutch TW, the 2-way clutch TW is set to the reverse rotation prevention state at the forward speed from the first speed to the eighth speed, and fixed at the reverse speed. Thus, each gear stage can be established. Furthermore, when the engine brake is applied at the first gear, it can be fixed.

  Further, by configuring the fourth brake B4 with the two-way clutch TW, when the upshift from the first gear to the second gear is performed by the action of the two-way clutch TW, the third brake B3 is simply switched to the fixed state. In addition, when downshifting from the second gear to the first gear, it is only necessary to switch the third brake B3 to the released state.

  Therefore, when shifting between the first speed stage and the second speed stage, it is necessary to switch the states of the third and fourth brakes B3 and B4 in the automatic transmission constituted by the dog clutch as the fourth brake B4. Compared to the one, only the state of the third brake B3 needs to be switched in the automatic transmission constituted by the two-way clutch TW as the fourth brake B4, and the controllability of the shift between the first gear and the second gear is improved. Can be made.

  If the 4th brake B4 is comprised by the 2 way clutch TW mentioned above, unlike the case where the 4th brake B4 is comprised by a friction engagement type brake, the friction loss by the 4th brake B4 will not generate | occur | produce. Accordingly, as in the case where the fourth brake B4 is configured by the meshing mechanism, the friction loss can be suppressed as the whole automatic transmission.

  Further, the two-way clutch TW as the fourth brake B4 includes, in addition to the above-described fixed state and the reverse rotation prevention state, a reverse rotation prevention state in which the third coupled body Cb-Cd is allowed to rotate forward and reverse rotation is prevented. The third coupling body Cb-Cd may be configured to be switchable to a forward rotation prevention state in which the forward rotation of the third connected body Cb-Cd is prevented and the 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, it is possible to establish eight forward speeds and one reverse speed. For example, the second speed and the seventh speed are omitted, and the sixth speed and the first reverse speed are omitted. 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 (fourth element), Cb ... carrier (5th element), Rb ... Ring gear (6th element), Pb ... Pinion, PGS3 ... 3rd planetary gear mechanism, Sc ... Sun gear (9th element), Cc ... Carrier (8th element), Rc ... Ring gear (1st element) 7 element), Pc ... pinion, PGS4 ... 4th planetary gear mechanism, Sd ... sun gear (12th element), Cd ... carrier (11th element), Rd ... ring gear (10th element), Pd ... pin On, B1 to B4 ... first to fourth brake, C1, C2 ... first, second clutch, 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 second planetary gear mechanism are a fourth element, a fifth element, and a sixth element, respectively, in order of arrangement at intervals corresponding to the gear ratio in the collinear diagram,
The three elements of the third planetary gear mechanism are the seventh element, the eighth element, and the ninth element, respectively, in the order of arrangement at intervals corresponding to the gear ratio in the collinear diagram,
As the tenth element, the eleventh element, and the twelfth element, the three elements of the fourth planetary gear mechanism are arranged in the order corresponding to the gear ratio in the alignment chart, respectively.
The second element and the sixth element are connected to form a first connection body, the third element and the eighth element are connected to form a second connection body, the fifth element and the The eleventh element is connected to form a third connecting body, the seventh element and the twelfth element are connected to form a fourth connecting body,
The first element is coupled to the input shaft, the tenth element is coupled to the output member;
As an engagement mechanism,
A first brake capable of fixing the fourth element to the transmission case;
A second brake capable of fixing the ninth element to the transmission case;
A third brake capable of fixing the second connector to the transmission case;
A fourth brake capable of fixing the third connector to the transmission case;
A first clutch capable of connecting the first element and the third connector;
A second clutch capable of connecting the first connecting body and the fourth connecting body;
By bringing at least three engagement mechanisms out of a total of six engagement mechanisms of the first to fourth brakes and the first and second two clutches into a connected state or a fixed state, An automatic transmission characterized by establishing each gear position. The automatic transmission according to claim 1, wherein the seventh element is a ring gear of the third planetary gear mechanism, and the twelfth element is a sun gear of the fourth planetary gear mechanism,
The fourth planetary gear mechanism is disposed radially outward of the third planetary gear mechanism, and a ring gear of the third planetary gear mechanism and a sun gear of the fourth planetary gear mechanism are integrally configured. And automatic transmission.   The automatic transmission according to claim 1 or 2, wherein the first brake is constituted by a meshing mechanism.   4. The automatic transmission according to claim 1, wherein the fourth brake is configured by a meshing mechanism. 5.   4. The automatic transmission according to claim 1, wherein the fourth brake includes a fixed state in which the third connecting body is fixed to a transmission case, and normal rotation of the third connecting body. An automatic transmission comprising a two-way clutch that is switchable between a reverse rotation prevention state that allows rotation and prevents reverse rotation.   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.

Images