1. Field of the Invention
The invention concerns a device for bringing up to speed a vehicle equipped with an automatic transmission according to the precharacterizing portion of claim 1.
2. Description of the Related Art
Conventional multi-stage or multi-gear automatic transmissions are conventionally provided, according to the state of the art, with a start-up or low gear device for providing the necessary start-up translation from the first gear of the transmission. In this state of the art, until now only two possibilities for realizing a start-up device of this type have been known. On the one hand, there is used a wet running start clutch (plate coupling), which operates without torque amplification, and on the other hand there is used a Foettinger fluid torque converter or hydrodynamic converter, which operates with a torque amplification of greater than one.
A working example of the second mentioned variety is described in greater detail below on the basis of
An automatic transmission 25 according to Lepelletier in accordance with the illustrative embodiment shown in
The input planetary drive 4 is comprised in known manner of a sun gear 9, the planetary gear 13 held by the planet arm or, as the case may be, planetary gear carrier 15 as well as the internal gear 14. From reference number 4 one can see that the sun gear 12, the planetary gear as well as the internal gear 14 engage in the conventional pair-wise manner, namely the sun gear 12 is in engagement with the planetary gear 13 and the planetary gear 13 with the internal gear 14.
The output planetary gear 5 is likewise comprised, in known manner, of a sun gear 16, an internal planetary gear 17 supported by the internal planet arm or, as the case may be, internal planetary gar carrier 21, the external planetary gear 18 held by the external planet arm or, as the case may be, external planetary gear carrier 22 as well as an internal gear 19. Further shown in this illustrative embodiment is a further sun gear 20.
From
The drive shaft 1 is connected with the internal gear 14 of the input planetary drive 4. The sun gear 12 of the input planetary drive 4 is connected fixed against rotation with the gear box or transmission housing 7. The planet arm 15 is on the one side connectable with the sun gear 16 via the clutch A, on the other side also a connection with the sun gear 20 can be established via clutch B. The two planet arms connected fixed against rotation with each other, inner planet arm 21 and outer planet arm 22, of the output planetary drive 5 are on the one side connectable fixed against rotation with the gear housing 7 via the brake D, on the other hand via clutch E a connection with the drive shaft 1 can be established. Besides the possibility of connecting the sun gear 20 with the planet arm 15 of the input planetary drive 4 via the clutch B, there exists beyond this the possibility to establish via brake C a connection fixed against rotation with the gear housing 7.
It can further be seen from
With the aid of the five shift elements, namely the three clutches A, B and E as well as the two brakes C and D, it becomes possible by the selective pairwise engagement to effect various transmission relationships between the drive shaft 1 and the driven shaft 2. There are possible a total of six forward gears, one braked neutral position as well as one reverse gear. A detailed discussion as well as the associated functional description can be found in the above-mentioned reference DE 690 10 472 T2.
According to the state of the art in order to bring up to speed a vehicle equipped with this automatic transmission 25 according to Lepelletier there is provided upstream a start up device with a hydrodynamic converter 3 comprised of pump gear 8, turbine wheel 9 and guide wheel or idler 10. In concrete form the turbine wheel 9 is connected with the drive shaft 1 of the above-described automatic transmission 25 according to Lepelletier. The idler wheel 10 is connected in known mode and manner with the gear housing 7 via a free wheel 11. The pump wheel 10 is connected with the motor shaft M. Further in accordance with the state of the art a torque converter bridge over or intermediate lock-up clutch 6 is provided, which after completion of the bringing up to speed process makes possible a direct connection between the motor shaft M of the internal combustion engine and the drive shaft 1.
Although this type of arrangement has been basically proven itself, and in particular the realization of an automatic transmission with very small dimensions has been made possible, there remains the need to further reduce the required construction space. Beyond this, it has been found that a consequence a speed up device with a hydrodynamic converter is a comparatively high fuel consumption.
The invention is thus concerned with the task, of providing a device for bringing up to speed a vehicle provided with automatic transmission between a drive shaft and a driven shaft in a transmission housing, which on the one hand exhibits small space requirement and beyond this makes possible greater fuel economy.
This task is solved by a device for bringing up to speed with the characterizing features of claim 1.
Advantageous embodiments and further developments of the invention are set forth in the dependent claims.
The invention is based upon the idea, that instead of the converter, one provides a planetary gear with at least three gears, of which one, in certain cases via further gear stages, is coupleable with the drive shaft and one, in certain cases likewise via further gear stages, is coupleable with the driven shaft and wherein the gear can be connected via a start-up brake, of which the brake force is controllable, with the transmission housing of the automatic transmission.
The planetary gear is preferably a simple planetary gear with a sun gear, a planetary gear and a internal gear, wherein for example the internal gear can be coupled with the drive shaft, the planetary gear can be coupled with the driven shaft via one or more gear stages and the sun gear is connectable with the housing via the above-mentioned start-up brake. This variant offers advantages particularly in that, since it uses a planetary gear, it involves a known simple construction with small space requirement.
In accordance with the invention it is envisioned, that the planetary gear is a component of the automatic transmission. The advantage of this variant is comprised therein, that according to the state of the art a large number of automatic transmissions include this type of planetary gear for changing gear ratio, preferably planetary gear sets.
It is frequently the case, that one gear of the above-mentioned planetary gear present as a component of the automatic transmission is connected fixed against rotation with the transmission housing. It is thus simply possible, to brake this fixed against rotation connection and to establish a controllable coupling via a start-up brake.
It is envisioned in accordance with the invention that the planetary gear, with which in accordance with the state of art one gear is connected fixed against rotation with the transmission housing, is a pre-provided step-down or reduction gear or a pre-provided step-up or increase gear of the automatic transmission. For realizing the invention this wheel is now connected with the transmission housing via the above-mentioned start-up brake.
It is envisioned in accordance with the invention to implement a device for starting up or bringing up to speed an admittedly known automatic transmission of the Lepelletier design. This variant has the advantage of a particularly small construction size.
For illustration purposes reference is made to the above-described embodiment in accordance with
It is envisioned in accordance with the invention, that the start-up brake is a friction brake, of which the slip is controllable. The employment of a friction type start-up clutch of this type with controllable or adjustable slip in the vehicle automatic transmission opens completely new and broad possibilities of the motor rotational speed adaptation, in order to increase fuel efficiency, without having to sacrifice performance. The herein introduced idea of a broadening of the function of the Lepelletier automatic transmission satisfies all current requirements of a modern vehicle transmission.
It is envisioned in accordance with the invention, to control the brake force of the start-up brake in such a manner, that this is smaller at the beginning of the start-up process than at the end of the start-up process. Preferably the brake force is so controlled, that at the beginning of the start-up process it essentially disappears, that is, that the start-up brake at the beginning at the start phase is opened, and that the brake after conclusion of the start-up process is arrested and therewith establishes a fixed against rotation connection of the sun gear to the transmission housing. Preferably the brake force is substantially continuously increased from the beginning of the start-up process up to the end of the start-up process.
Based upon the transmission according to the state of the art according to the illustrative embodiment shown in
The illustrative embodiment of an automatic transmission shown in
The components of the automatic transmission 26 according to Lepelletier are in accordance with the above-mentioned figure wherein the identical reference numbers are used for the same or similar components:
For the concrete coupling of the individual components as well as for the functioning of the automatic multi-gear transmission reference is made to the above description as well as the examples in the therein mentioned reference DE 690 10 472 T2.
In accordance with the invention there is now provided, in place of the hydrodynamic converter 3 and the converter bridge clutch 6 according to the state of the art, a controlled slip friction type start-up clutch, referred to in the following as start-up brake S. This start-up brake S is provided in place of the fixed against rotation connection between the transmission housing 7 and the sun gear 12 of the input planetary drive 4 and provides a controllable connection between the transmission housing 7 and the sun gear 12 of the input planetary drive 4.
The motor shaft M is now no longer connected with the drive shaft 1 via the converter 3 or the converter bridging clutch 6, but rather is preferably provided as a preferably direct fixed against rotation or oscillation dampened connection of the motor shaft M with the drive shaft 1.
The manner in which the inventive device functions for starting up an vehicle will be described in the following in greater detail on the basis of
During the start-up process in the presently discussed automatic transmission 26 according to Lepelletier both the clutch A as well as the brake D are closed, while the clutch B and E as well as the brake C are in the open position.
At the beginning of the start phase the start-up brake S is opened. By the rotation of the drive shaft 1 connected with the motor shaft M of the internal combustion engine the internal gear 14 or the reduction gear 27 provided upstream as input planetary drive 4 is driven with motor speed of rotation nM. The internal gear rate of rotation n14 is thus identical to the motor rate of rotation nM.
The planet arm 15 of the input planetary drive 4 is connected with the drive shaft 2 and therewith with the vehicle drive shaft F via the arrested clutch A and the output planetary drive 5. Since the vehicle is not moving, the value of the vehicle drive shaft rotation speed nF and therewith likewise the planet arm rotational speed n15 of the input planetary drive 4 is zero:
nF=n15=0
Since the reduction stage 27 is not an input planetary drive 4 with a negative level of translation iO, in the described case the sun gear 12 rotates with the added on start-up brake S against the motor direction of rotation with the rotational speed
nS=iO×nM.
Directly after the start-up the brake force of the start-up brake S is increased. The sun gear 12 of the input planetary drive 4 is now no longer completely freely moveable. This has the consequence, that besides the rotation of all gears 12, 13, 14 of the input planetary drive 4 also a rotation of the planet arm 15 can occur.
The left side of the diagram represents the input planetary drive 4, the right side of the diagram
As can be seen from the diagram
n14=nM.
The speed of rotation nS of the start-up brake S and therewith the rotational speed n12 of the sun gear 12 of the input planetary drive 4 is slightly reduced as a result of the brake effect:
nS=n2<iO×nM.
(iO level of translation).
At the point of intersection of the degree of translation 23 determined by the rotational speed n14 of the internal gear 14 and the rotational speed n12 of the sun gear 12, with the vertical associated with the planet arm 15, there results the value of the planet arm rotational speed n15.
This planet arm rotational speed n15 is transmitted to the sun gear 16 of the output planetary drive 5 by means of the closed clutch A. The corresponding intersection with the vertical corresponding to the sun gear 16 can likewise be taken from the diagram
With increasing vehicle speed the start-up brake rotational speed nS drops. The driven rotational speed, represented by the vehicle drive shaft rotational speed nF, thereby increases continuously. The torque TS to be applied from the start-up brake S thereby corresponds to the factor of the reduced degree of the actual gear translation iO of the transmission input torque TM:
TS=TM/iO.
The reduction stage of the input planetary drive 4 in the Lepelletier system 26 generally exhibits a degree of translation iO of approximately 2. Therefrom there results a reduced brake moment TS reduced by a factor of iO=2 compared to the transmission input moment TM.
Diagram
The braking of the start-up brake S is continued, until its rotational speed nS and therewith also the sun gear rotation speed n12 of the input planetary drive 4 reaches a speed of zero.
Therewith the planet arm rotation speed n15 of the input planetary drive 4 increases to the maximum value n15, max. as a fixed relation to the motor rotation speed nM. The vehicle drive shaft rotation speed nF as driven rotational speed of the automatic transmission 26 reaches the relative value to the motor rotation speed nM corresponding to the translation ratio in the first gear.
Number | Date | Country | Kind |
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101 61 815.8 | Dec 2001 | DE | national |
Number | Date | Country | |
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Parent | 10318617 | Dec 2002 | US |
Child | 11054935 | Feb 2005 | US |