Powershift type countershaft transmission for vehicles

p0001The invention relates to an interruption in tractive force shiftable countershaft transmission for motor vehicles, of the type described in the preamble of claim 1.

p0002From DE-OS 40 31 851 discloses a loss of traction unlockable countershaft transmission for motor vehicles, of the type described in the preamble of claim 1 is known.

p0003In this known countershaft gear is disposed between a flywheel forming the input component of a friction clutch, a direct driving connection to a first transmission input shaft is provided and the output part of the friction clutch is the extensive first transmission input shaft second transmission input shaft connected to a in the form of a hollow shaft. On the first transmission input shaft here are essentially the fixed gears of the gear stages and on a parallel to the two transmission input shafts arranged countershaft the idle gears of the gear stages are arranged substantially, being arranged between paired idle gears on the countershaft shaft claw or synchronous clutches to the individual gears to turn.

p0004On the second transmission input shaft, in this case, the fixed wheels of the lowest and the highest speed stage are disposed, and in contrast to the other speed stages, the fixed wheel on the countershaft and the idler gear on the first transmission input shaft is at the second highest speed stage arranged.

p0005Should this known countershaft gear, the motor vehicle to be approached, as a driving connection between the loose wheel of the first gear and the countershaft must be made by inserting the sliding sleeve for 1st gear. Subsequently, it is carried out by controlled engagement of the friction clutch of the starting process. Should be switched now from 1st gear to 2nd gear, it must at the beginning of the shift, the friction clutch is disengaged, so that the sliding sleeve, which is scheduled for the 1st and 5th gear, designed from the 1st gear and in the 5th gear can be engaged. Now, the friction clutch is engaged again controlled, resulting in the abrasive friction clutch in connection with the translation of the 5th gear a speed adjustment to the loading speed of the 2nd gear. Once the appropriate loading speed has been reached, a bumpless loss of traction-free shifting into 2nd gear can be done now by shifting the sliding sleeve for the 2nd gear.

p0006However, the known countershaft gear case has the disadvantage that a short-term interruption of traction occurs by the required beginning the shift from 1st gear to 2nd gear disengagement of the friction clutch, which can lead to an undesirable revving the engine.

p0007From EP-PS 0,173,117 a loss of traction unlockable countershaft transmission for motor vehicles is known, in which a drive motor through a direct connection drives a first transmission input shaft on which a plurality of fixed gears of gear stages is arranged and a countershaft parallel arranged on which a plurality of idler wheels for the different gear stages are arranged, in each case one claw or synchronous clutch is arranged between paired idle gears.

p0008With the transmission input shaft, which is connected directly to the drive motor, the input part of a friction clutch is rotatably connected, the output member is connected to a second transmission input shaft in the form of a hollow shaft on which the fixed wheels of 5th gear and reverse gear are arranged.

p0009A starting process of the motor vehicle is started by inserting the sliding sleeve in the 5th gear, said first friction clutch is disengaged. Subsequently, the friction clutch is now controlled so engaged by grinding, so that once the insertion speed is reached for the 1st gear, the sliding sleeve can be inserted smoothly into 1st gear and then the friction clutch is disengaged because of the torque is transferred via the wheel of the 1st gear. the friction clutch to engage 2nd gear again dragging engaged in a controlled manner, so that the insertion speed of the 2nd gear can be set, after which on reaching this speed, the sliding sleeve is moved for the 2nd gear to the wheel for the second bringing gear to transfer torque. Subsequently, the friction clutch is disengaged again.

p0010The known countershaft transmission has the disadvantage that, since the starting operation on the gear ratio of the highest gear, such as the 5th gear is performed, the friction clutch must have a considerable friction loss and hatchability, which often no longer the usual at power generating simple toughened friction clutch can be used, but a current in lubricating oil wet multiple disk friction clutch has to be used.

p0011The object of the invention is to improve a countershaft transmission as explained in the preamble of claim 1 kind that using the simpler single-friction clutch, a tractive force interruption-free switching of all grades is made possible without the critical starting range during gear changes between the first and 2nd gear, a torque interruption occurs.

p0012According to the invention this object is achieved by a countershaft transmission as explained in the preamble of claim 1 type, having the indicated in the characterizing part of patent claim 1.

p0013Characterized in that the provided between the input part of the friction clutch and the first transmission input shaft direct connection is formed as a shiftable claw clutch, and between the output part of the friction clutch and two transmission input shafts, a switchable synchronizer clutch is provided, which starting process via the controlled friction clutch and the transmission ratio of 1, occur. passageway, whereupon only the direct connection between the input part of the friction clutch and the first transmission input shaft is made by the dog clutch switchable.

p0014If now for switching from 1st to 2nd gear, the friction clutch is disengaged, a torque path through the switched claw clutch for wheel of 1st gear is maintained and there is no disturbing revving the prime mover. The switchable synchronous coupling that is connected to the output of the friction clutch, is now brought into engagement with the gear set of the 5th gear and then engaged again controlled friction clutch. Once the loading speed of the 2nd gear is reached, the sliding sleeve of the 2nd gear is shifted to make the wheel of 2nd gear positively and after disengaging the friction clutch, the torque is transmitted now exclusively through the wheel of 2nd gear.

p0015In the further claims expedient embodiments of the invention are explained.

p0016The invention will be explained in more detail with reference to an embodiment shown in the accompanying drawings. It shows:<dl id="dl0001"><dt>Fig. 1</dt><dd>a transmission diagram of a countershaft transmission according to the invention in the neutral position;</dd><dt>FIG. 2</dt><dd>the transmission diagram of Figure 1 in the switching position for a starting that the torque transmission path forming gear parts have been drawn in their respective switching position and the torque curve illustrated by enhanced strokes.</dd><dt>Fig. 3</dt><dd>the transmission diagram of Figure 1 after completion of starting operation in 1st gear.</dd><dt>Fig. 4</dt><dd>the transmission diagram in the switch position for the preparatory phase of a gear shift from 1st gear to 2nd gear;</dd><dt>Fig. 5</dt><dd>the transmission diagram of FIG. 1 during the synchronization phase for a shift from 1st to 2nd gear and</dd><dt>Fig. 6</dt><dd>the transmission diagram of Figure 1 in its operating position by a closed circuit from 1st gear to 2nd gear.</dd><dt>Fig. 7</dt><dd>the transmission diagram of FIG. 1 in the preparation stage for a shift from 2nd gear to 1st gear and </dd><dt>Fig. 8</dt><dd>the transmission diagram of FIG. 1 after the conducted circuit from 2nd gear to 1st gear.</dd></dl>

p0017The structure of the countershaft transmission of the invention is explained in conjunction with FIG. 1, in which the individual transmission elements are provided with corresponding reference numerals, which are repeated in the other figures 2 to 8 with the only difference that the turned-on in the torque path transmission parts in their switched positions are drawn and the power flow is indicated by enhanced strokes.

p0018A drive motor 1, preferably a combustion engine with a crankshaft 2 drives a flywheel 3, which is conventionally connected with a friction disc clutch 4, which consists essentially of an input element and an output element 5. 6

p0019The countershaft transmission comprises a first transmission input shaft 7 and a second transmission input shaft 8, the second transmission input shaft, the first input shaft 7 comprehensive hollow shaft 8 is formed as one. The countershaft transmission gear sets are arranged for the gears 1 to 5, wherein preferably the fixed gear wheels 9, 11, 13 and 15 on the first transmission input shaft 7 are arranged and their mating gears or idler gears 10, 12, 14 and 16 in a direction parallel to the transmission input shafts 7 and 8 arranged countershaft 17 are arranged. The countershaft 17 is connected to a final drive 18th

p0020From gear set 19 and 20 of the 5th gear, the fixed wheel 19 is fixed on the countershaft 17 and the idler gear 20 is disposed on the second transmission input shaft. 8

p0021Between two adjacent loose wheels 10 and 12 or 14 and 16 synchronous clutches are arranged with corresponding sliding sleeves 21 and 22 in known manner.

p0022In contrast to the known prior art, the direct connection between the flywheel 3 and the first transmission input shaft 7 is formed as a shiftable jaw clutch 23 and the output member 6 of the friction clutch 4 is not in direct driving connection with the first transmission input shaft 7, but is connected to this via a switchable clutch synchronous connectable 24 or with the arranged on the hollow shaft 8 loose wheel 20 of the 5th gear.

p0023The operation of the countershaft transmission of the invention is described in connection with Figures 2 to 8 explained, in which the respective torque transmission gear forming elements are highlighted by a larger line width.

p0024From Fig. 2, the starting process can be seen, in which at first still disengaged friction clutch 4, the synchronizer clutch 24 is shifted such that a driving connection between the output member 6 of the friction clutch and the first transmission input shaft is made. Is now transmitted by a controlled engagement of the friction clutch 4 a torque, this torque is transmitted via the synchronous clutch 24 to the first transmission input shaft 7 and from there via the gear set of first gear and located in the position for the 1st speed synchronizer clutch 21 transmitted to the countershaft to this and forwarded to the final drive 20th

p0025If the starting process is completed, the friction clutch, as shown in FIG. 3 shows four disengaged and the dog clutch 23 engaged in its place, which establishes a direct driving connection between the flywheel 3 and the first transmission input shaft 7. The additional torque flow remains above the gear set of the first gear and the synchronizer clutch on the countershaft and the final drive.

p0026If now 3 a shift from 1st gear to 2nd gear will be prepared starting from the shift position in FIG., First the synchronizer clutch 24 is brought into engagement with the loose wheel 20 of the 5th gear and thereafter the friction clutch 4 is controlled indented, up by the gear set of the 5th gear extending torque flow relief of gearset 1st gear causes, whereby this, as shown in FIG. 5, switched from FIG. 6 position shown for the 2nd gear to neutral and then in the can be. Below this circuit, the friction clutch 4 is disengaged again and the Drehmomentübertragungsfluß runs over the dog clutch 23 and the gear set of the 2nd gear.

p0027If now for example again a downshift from 2nd gear to 1st gear carried, so the friction clutch 4 is controlled again engaged, thereby transmits torque through the still engaged synchronizer clutch 24 on the loose wheel 20 of the 5th gear and until again the gear set of the 2nd gear is torqueless because the inserted with a slipping clutch 5th gear stage takes over the torque transmission. Therefore, without any problems, a circuit of the synchronous clutch from the position of the 2nd gear then take place in the neutral position and in the position for the 1st gear, and by disengaging the friction clutch 4 is reproduced below a torque flow via the dog clutch 23 and the gear set of the 1 provided. Ganges.

p0028The inventive design of the countershaft transmission provides the advantage that the starting process can be carried out via the gear set of the first gear and the same is ensured by the additional couplings 23 and 24, that and a gear change from 1st gear to 2nd gear the case required disengagement of the friction clutch 4 no runaway of the drive motor may occur.

p0029Of course, the link according to the invention of controlled friction clutch 4 and the transmission input shaft 7 and 8, the various transmission configurations are subsequently possible, but without broadening the scope of the present invention.

p0030For example, the output element of the friction clutch can be connected via further couplings optionally with the loose wheel of the highest gear, with the first transmission input shaft or with any other loose wheel of a gear.

p0031The output element of the friction clutch can be connected via further couplings optionally with any loose wheels or with the first transmission input shaft.

p0032Instead of the simple friction clutch can be used, of course, a wet multi-plate or other suitable couplings.