FR2479938A1 - Hydrodynamic transmission with regenerative braking - has flywheel with hydraulic coupling to drive shafts - Google Patents

Abstract

The hydrodynamic transmission with regenerative braking has a large mechanical flywheel (23) coupled to the output shaft (16) by a hydraulic clutch and mechanical gearing. The flywheel is coupled to the drive shaft (10) by a similar arrangement while the drive shaft is coupled to the output shaft by a hydrodynamic transmission. The hydraulic clutches and mechanical gearing provide a simple, low cost transmission which is easily adapted to the different speeds of the flywheel. The system optimises the regenerative braking with the mechanical gearing adjusted to cater for different speed ranges of the flywheel.

Description

 We have known for a long time from the specialized literature, and in particular from the West German patents DE-PS 629 771 and 660 186, the combination of a hydrodynamic transmission for a vehicle with an energy accumulator with flywheel. This attempt was made to charge the energy accumulator, and also to discharge it, by means of a hydrodynamic torque transmission element (converter or clutches).

 The considerations and concerns of specialists, currently challenged by the constraints relating to energy saving, also go, at least partially, in the sense of providing an energy accumulator with flywheel, which exerts a braking effect. load and contributes to acceleration during discharge. Under these conditions, such an installation is based on the following basic principles: the energy input to the flywheel (during braking) is always linked to an increase in its rotation speed in rpm, while at l Conversely, the delivery of energy is always accompanied by a decrease in the speed of rotation. For these reasons, it is necessary to use transmissions with continuous change or variation of ratio to charge and discharge the energy accumulator with flywheel. However, to date, no hydrodynamic transmissions have been used. for this reason.

 Contrary to this, there are widely held opinions among specialists, as an article entitled "Schwungrad-Energiespeicher fur Strapenfahrzeuge" ("Energy accumulator with flywheel for road vehicles") published in VDI-Nachrichten of 09/09/77, page 18. It is considered here that the hydrodynamic transmissions are not suitable for this application, because of their too bad efficiency. These arguments will however be eliminated by the present invention.

 More particularly, the present invention aims to solve the problem posed by the improvement, in this sense, of a system for torque transmission and recovery of braking energy, which comprises an energy accumulator with flywheel and a hydrodynamic torque converter for charging and discharging the energy accumulator, so that the charging and discharging of this energy accumulator takes place with the minimum of losses and so that the whole system can be produced in a different manner. as economical as possible.

 To solve this problem, the invention is based on a known installation shown in Figure 5 of RFA 629 771 cited above, where a drive shaft 2 can be coupled to a driven or outgoing shaft 16 via d a first hydrodynamic torque transmission element (clutch 17). An energy accumulator in the form of a flywheel 13 is firstly coupled via a second hydrodynamic torque transmission element (clutch K with variable degree of filling) and via d 'a mechanical transmission (3a, 4a) to the motor shaft 2, and on the other hand constantly connected through a third hydrodynamic torque transmission element (converter W) and another mechanical transmission (3, 4) to the motor shaft 2. Under these conditions, the energy accumulator can be charged in two ways: either from the machine or from the propulsion motor 1 via the mechanical transmission 3, 4 and through the converter hydrodynamic torque W, either (for the purpose of braking the driven or outgoing shaft 16), from the drive shaft through the mechanical transmission 3a, 4a and also by the hydrodynamic clutch K.

The discharge of the energy accumulator, that is to say the supply of torque effected by using the energy previously accumulated to actuate the driven or output shaft 16, cannot occur in this case only through the second hydrodynamic transmission element, therefore through the aforementioned clutch K.

Consequently, the hydrodynamic torque converter W arranged between the flywheel 13 and the motor shaft 2 can basically transmit the torque only in one direction. Nor can it be used to discharge the energy accumulator, since it can only be used to supercharge the machine or the motor 1.

 In the known installation, the last clutch or hydrodynamic coupling device K mentioned above, if one wishes to recover the braking energy and then make it reusable, must transmit the torque in both directions. As a result, this clutch or coupling device must be produced with a normal blading parallel to the axis; thus, it has only a low specific yield, that is to say a low power density. In addition, this coupling works with high losses in most of its operating range.

According to the present invention, and unlike the known system, there is a provision which can be summarized as follows
The discharge of the energy accumulator no longer takes place (by passing through the second hydrodynamic torque transmission element) directly on the driven or output shaft, but first by passing through the motor shaft and , in fact, through the third hydrodynamic torque transmission element designed in the form of a hydrodynamic coupling device (release clutch).

From the drive shaft, the accumulated energy is re-introduced via the first hydrodynamic torque transmission element, constituted as it is already known by a hydrodynamic torque converter, in the output or driven shaft . This torque converter constitutes an important element of the hydrodynamic transmissions incorporated in any case in many power plants. According to the present invention, the discharge of the energy accumulator is done through two hydrodynamic torque transmission elements arranged in tandem, which is unusual in this particular technical field. Thanks to this arrangement, the change or variation necessarily continuous of the ratio between the rotational speeds in rpm of the flywheel and the driven shaft takes place largely in the torque converter, so that the release clutch can work with relatively slip values weak. In comparison with the known system, the discharge thus takes place with better efficiency, on average, despite the tandem arrangement of two hydrodynamic torque transmission elements.

 During the discharge of the energy accumulator, the machine or the drive motor can be set to a reduced power speed; preferably, the machine or the drive motor will be allowed to operate at its maximum power, so that the power drawn by the 4 ’energy accumulator remains available as a complement. In all cases, the power delivered by the energy accumulator must be adjustable, and this especially for the simple reason that as a general rule one cannot increase at will the total power transmissible by the transmission or gearbox , in particular through the torque converter. This partial problem is however solved according to the present invention, whether this torque converter is designed in the form of an adjustable converter, that is to say adjustable by the adoption of guide vanes, or that the unloading clutch is designed in the form of an adjustable clutch or coupler (for example with variation of its degree of filling). By this means, it is also possible to ensure, for example in the case of a vehicle moving on rails, that the entire torque of the output shaft does not exceed the limit of friction between the drive wheels and the rails. If an adjustment converter is used, the discharge coupler or clutch can operate with a particularly low slip rate, therefore with particularly satisfactory efficiency.

 Whereas the discharge of the energy accumulator takes place on the primary shaft of the transmission or gearbox, we realize the hypothesis that the second hydrodynamic torque transmission element, or the "charge coupler" , has no other function than that of charging the energy accumulator. In other words, this element only has the role of recovering the braking energy. Unlike the system mentioned above, this charge coupler is no longer intended to discharge the energy accumulator.

In other words, the load coupler or clutch should only transmit the torque in one direction. Consequently, this coupler or clutch can be provided with a vane oriented obliquely to the axis, in the manner of a hydrodynamic brake, so that its size is relatively reduced. It follows that the clutch or coupler can transmit a high specific power (high power density). Granny, its cost is particularly advantageous.

 Another important concept of the invention, which leads to a further development thereof, resides in an alternative embodiment according to which the discharge operation or process takes place only above a minimum prefixed number of revolutions of the shaft leading to the motor (approximately 50% of its maximum speed in rpm). Thus, several advantages are obtained: on the one hand, the relationships between the respective speeds of rotation of the flywheel and of the motor shaft are maintained in a relatively restricted range; on the other hand, during the discharge process the torque converter works in a particularly high efficiency range. Finally, it should be taken into account that, in the case of rail vehicles (for which the transmission according to the invention was designed in the first place), the torque supplied at the bottom of the range of walking speeds (taking into account the friction limit mentioned above between the drive wheels and the rails) must in any case be limited. In this way, the accumulated energy will be preferred for acceleration at the top of the range of walking speeds, where additional power is supplied to the machine or the propellant motor in the form of power extracted from the energy accumulator. is much more useful than in the range of starting speeds.

 By limiting the range of rotational speeds of the flywheel, and according to another improvement provided by the present invention, the range of necessary adjustments of the first or third hydrodynamic torque transmission element can be kept within relatively narrow limits. Consequently, the recovery of braking energy will therefore be limited in the range between 100% and approximately 50% of the maximum number of revolutions minute. Thanks to this measure, the charge coupler works in a relatively favorable yield range; it can be operated for example between slip values between 65% and 10%. Otherwise, for example during braking of a vehicle to go from 100 to 50% of its maximum speed, we already subtract 75% of kinetic energy of the mass of the vehicle. A recovery of the braking energy in the area below 50% of the maximum speed is of little interest.

 Other preferred embodiments of the charge coupler according to the invention can also be envisaged; for example, this coupler can optionally be replaced by a hydrodynamic brake.

This allows hydrodynamic braking up to relatively low walking speeds.

 According to a particularly advantageous embodiment of the invention, it is possible to combine the whole of the transmission in the form of a current hydrodynamic gearbox of the commercial which is normally used only for traction, in which a gearbox is incorporated. mechanical which connects the motor shaft to the flywheel, with a second transmission part which comprises the load coupler or clutch, the discharge coupler or clutch and said mechanical gearbox. This second part of the gearbox also incorporates the energy accumulator.

An exemplary embodiment of the invention will now be described with reference to the accompanying drawing, in which
FIGURE 1 schematically shows a hydrodynamic transmission with energy accumulator by flywheel; and
FIGURE 2 shows a partial section taken along line II of Figure 1.

 The transmission shown comprises a driving or driving shaft 10, integral with a toothed wheel 11, as well as two hydrodynamic torque converters 12 and 13, namely a starting converter 12 and a cruising converter 13. The impellers of these two converters are not shown in detail in the drawing. The converters comprise a common hollow shaft of pump rotor 14, also integral with a toothed wheel 15, which meshes with the toothed wheel 11, as well as a common central shaft 16 of turbine wheel, which at the same time constitutes the transmission output shaft. The drive shaft 10 of the transmission can be driven by a machine or a motor (not shown); this shaft comprises a revolution counter socket 17. The speed of rotation thus measured will be designated by the expression n1.Another revolution counter socket 18 is also provided on the output shaft 16. The number of rpm measured by this socket 18 will be indicated later by the expression n2.

 Whereas the transmission is preferably designed to propel a vehicle, we will couple to the output shaft or driven 16 a direction reverser (not shown in the drawing), the output of which will be connected to the drive wheels of the vehicle.

 The part of the transmission which has been described so far is known in the art. It is housed in a casing 19. In another casing 20 juxtaposed with the previous one are essentially mounted two hydrodynamic clutches 21 and 22 whose respective role consists in charging or discharging an energy accumulator 23 of the flywheel type. The latter is housed in a complementary casing 24.

 The load clutch 21 comprises a primary rotor with blades 25 fixed on an extension of the drive shaft 16, as well as a secondary rotor with blades 26. The latter rests on a shaft 27 on which is fixed a toothed wheel 28. The load clutch 21 further comprises a fixed casing 29, a filling line 30 and a discharge line 31. Between the two vane rotors 25 and 26, a sliding diaphragm 32 can be inserted, the adjustment of which takes place thanks to a jack 33. When the latter is supplied with pressurized fluid through the pipe 34, the sliding diaphragm 32 is extracted between the rotors 25 and 26, and in the absence of this pressurized fluid it is a spring which recalls the diaphragm inwards. All these organs, as well as the entire transmission, are only shown schematically in the drawing.

 Near the load clutch 21 is arranged a clutch or discharge coupler 22 arranged coaxially with respect to the flywheel 23. The primary vane rotor 35 of this clutch 22 is connected by a shaft 36 to a toothed wheel 37 and the flywheel 23. On the other hand, the secondary rotor 38 is mounted on the end of a shaft 39 secured to a toothed wheel 40 which meshes with a toothed wheel 41 fixed on the shaft 14 of the pump rotor .

A shell 42 fixed to the secondary rotor 38 envelops the primary rotor 35 and has discharge orifices 43. The filling of the discharge clutch 22 takes place through a filling pipe 44.

 To supply the hydrodynamic torque transmission elements 12, 13, 21 and 22 there is provided a filling pump 45 which sucks the fluid in a branch 9; this pump discharges the working fluid into a pressure line 46. From there, this fluid can be directed either through a stop valve 47 to the start converter 12, or through another stop valve 48 to the cruise converter 13, again through another valve 49 and the filling line 30 to the load clutch 21, and finally, through an additional valve forming a throttle adjustment valve 50 and the filling line 44 to the discharge clutch 22. By adjusting the throttle valve 50 appropriately, the degree of filling of this discharge clutch 22 can be adjusted. This makes it possible to modify the motive power transmitted between the flywheel 23 and the rotor shaft. pump 14.

 A relief valve 51 is inserted into the exhaust line 31 of the load clutch 21. On the movable shutter member of this relief valve 51 acts the pressure prevailing in the exhaust pipe 31, and this in the direction of opening, as schematically shown in the pilot bypass shown in broken lines at 52. The pressure prevailing in another pilot line 53 acts on the contrary in the opposite direction and its value can be adjusted by means of a pressure valve. throttle 54. This makes it possible to adjust the torque transmitted via the load clutch 21 between the drive shaft 16 and through the transmission elements 27, 28 and 37 to the flywheel 32 at different values. The pressure prevailing in the exhaust pipe 31 is even, at the very least, close to a value corresponding to the torque transmitted by the load clutch 21.

 Figure 2 shows schematically in partial cylindrical section the blade of the load clutch 21. we see that the blades are arranged obliquely, which increases the transmissible torque in the direction of rotation P compared to an arrangement comprising vanes parallel to the axis.

 To control the entire transmission, a control unit is designated symbolically at 60. In this control unit there are two signal conductors a and b. The signal conductor a can convey an acceleration command and the signal conductor b can convey a braking command. In addition, the control unit 60 receives measurement signals transmitted from the corresponding taps to indicate the momentary values of n1, n2 and nS (rpm). This last symbol nS designates the speed of rotation in rpm of the accumulator 23, which is measured by taking the tachometer 59. In the case of an acceleration order, it occurs first, by the through one of the pilot lines 57 or 58, the opening of one of the stop valves 47 or 48, which ensures filling of one of the torque converters 12 or 13. This is the momentary value of n2 / n1 ratio of rotational speeds which determines which of the two converters 12 or 13 will be filled, as is well known in the art of hydrodynamic transmissions.

 When a braking command is issued and as long as the number of rpm (n2) of the output shaft exceeds a pre-established limit value, for example more than 50% of the maximum speed of rotation of the shaft disengaged, line 34 remains under pressure.

This results in the following operations: in the load clutch 21 the sliding diaphragms 32 are pulled outwards.

At the same time, the shut-off valve 49 opens, which allows the working fluid to reach the interior of the load clutch 21.

In addition, the pressure rises in the pilot line 53. Consequently, the load clutch 21 operates so as to equalize the rotational speeds of the shafts 16 and 27; in other words, the drive shaft 16 will be braked while the flywheel 23 will be accelerated. In order to allow the maximum energy to be stored in this flywheel 23, it is advisable to choose a transmission ratio as high as possible between the toothed wheels 28 and 37. As soon as the braking process has ended, or when the rotational speed n2 of the drive shaft drops below the aforementioned limit value, the load clutch 21 is again discharged. This load clutch 21 can also be evacuated when the flywheel d inertia 23 reaches a maximum speed of rotation. Optionally, it can also be braked by mechanical means.

 The energy stored or accumulated in the flywheel 23 can be made available again by proceeding as follows when the speed of rotation n2 of the driving shaft 16 exceeds a preset value, for example the above-mentioned limit value, and when it is necessary to produce an acceleration with a substantially increased power, the more or less large opening of the throttle valve 50 is caused via the pilot line 61, which makes it possible to fill to a determined degree the release clutch 22. This ensures the increase in the speed of rotation of the pump rotor 14 to a value which cannot normally be achieved on the side of the drive machine. Excessive power transmission therefore occurs through that of the converters 12 or 13 which is engaged. Usually, in this case, the cruise converter 13 is engaged. During this process, it may be preferable to have the setting of the throttle valve 50 and, therefore, the degree of filling of the relief clutch 22, be a function of the ratio between the rotational speeds nS and n1. The lower this ratio, the more the discharge clutch 22 can be filled.

  When this ratio between the rotational speeds falls below a preset value, or when the acceleration is finished, the throttle valve 50 is closed, which determines the evacuation of the discharge clutch 22. Au During the next braking process, the cycle described above can be repeated.

 The transmission according to the present invention is particularly suitable for an installation where the drive machine is constituted by an electric motor. Consequently, the transmission will preferably be used on vehicles with electric traction on rails, and mainly on vehicles of this type designed for short distance lines, such as commuter lines, where they are subjected to frequent accelerations and decelerations.

Claims (11)

 1. Hydrodynamic transmission comprising a device for recovering braking energy and making it reusable, in particular for vehicles, and preferably for vehicles intended for relatively short journeys, this transmission essentially comprising  a) a primary shaft (10/14) to which the drive motor  can be linked and which can be coupled in turn  via a first transmission element  torque hydrodynamics (12 or 13) to an output shaft  (16) ;;  b) an energy accumulator with a flywheel (23),  which is coupled via a second element  hydrodynamic torque transmission (21), namely  via a hydrodyna adjustment clutch  mique, with variable degree of filling, and of a mechanical gear (28/37) with the shaft c (output or 'm'ne (16), to.en being  also maintained in connection through a third element  hydrodynamic torque transmission (22) and a  other mechanical gear (40/41) with the primary shaft  (10/14); this hydrodynamic transmission being characterized in that:  c) the third hydrodynamic transmission element of  torque (22) is produced in the form of a hy clutch  drodynamic or release clutch, which is disengaged  able and engaging;  d) the first hydrodynamic transmission element of  couple (12, 13) is designed in the manner known as  a hydrodynamic torque converter;  e) the first (12 or 13) or third (22) element of  hydrodynamic torque transmission is adjustable in  function of the power to be transmitted;  f) the vanes of the second hydrodyna transmission element  torque mique (21) which serves exclusively as a clutch  load ages are arranged obliquely to  11 axis of rotation to increase the maximum value  admissible to transmit to the flywheel (23)  2.Transmission according to Claim 1, characterized in that there is provided a control and piloting device (60, 49) which makes it possible to control the engagement of the load clutch (21) upon receipt of a braking order (b).  3. Transmission according to either of Claims 1 or 2, characterized in that a command and control device (60, 50) does not engage the release clutch (22) upon receipt of an acceleration order that above a determined minimum number of rpm of the output shaft (16), for example only above approximately 50% of the maximum speed of rotation of this shaft .  4. Transmission according to any one of Claims 1 to 3, characterized in that the lowest usable speed of rotation, in rpm, of the flywheel (23), which preferably is a function of the nominal speed of rotation of the drive motor, is only between approximately 20 and approximately 40% below the maximum speed of rotation of the flywheel.  5. Transmission according to any one of Claims 1 to 4, characterized in that the control and piloting device (60, 499 of the load clutch (21) only triggers the latter in the region of the higher speeds of shaft rotation & output (16) ,, which is approximately between 50 and 100% of the maximum speed of rotation of this shaft.  6. Installation according to any one of Claims 1 to 5, characterized in that the load clutch (21) comprises, according to the known mode, a fixed shell (29) which envelops the two vane rotors (25, 26 ) and which is connected to the two filling (30) and evacuation (31) pipes respectively.  7. Installation according to Claim 6, characterized in that members (49, 51, 54) intended to control the filling and / or the evacuation of said load clutch (21) are connected to said shell (29).  8. Installation according to either of Claims 5 or 6, characterized in that there is provided in the shell (29) movable shutter means (32), of the type well known in the technique of hydrodynamic brakes, to reduce ventilation losses when the load clutch (21) is neutralized.  9. Installation according to any one of Claims 1 to 8, characterized in that the impeller rotor (26) flywheel side (23) of the load clutch (21) can be uncoupled and made integral under braking flywheel (23).  10. Installation according to any one of Claims 1 to 9, characterized in that the load clutch (21), as is known in the technique of hydrodynamic brakes, comprises an adjustment device (51 to 54) which controls the degree of filling of this load clutch, so that the resulting braking torque is adjusted to a value corresponding to a variable reference value.  11. Installation according to any one of Claims 1 to 10, characterized in that the first hydrodynamic torque transmission element (12, 13) connected by the mechanical gear (40/41) to the flywheel (23) is joined with this gear in a first housing part (l9) e and that in addition the load clutch (21) the release clutch (22) and the mechanical gear (28/37) which connects the load clutch (21) on the flywheel (23) are united in a second housing part (20), preferably fixed directly to the first part (19).