HYDROSTATIC TORQUE CONVERTER

" Hydrostatic Torque Converter " When usin* an internal combustion engine as a source of power in vehicles, earth movxng machines etc.the power transmission has a central significance in prac¬ tical conditions. The adaptation of the revolution spesd of the engme and the cardan axle to Rach other so that on the cardan axle prevails the torque required bv the iondin,; in the different driving situations implies the use of a transmission functionins at several gearing ratios. The different gearing ratios are then ootained mnSt usually by means of near wheels. When the average driving speed in the European automobile traffic is estimated at 18.5 km/h, it means frequently repeated stops, shifting to different gears as well as plentiful driving at low gears and lignt engine loadinr- In these conditions the fuel economy of the combustion engine is really poor and the power transmission losses are maxim-urn, calculated in percentages.

A decisive improvement would thus require the development of a transmission func¬ tioning in a wide gearing ratio range and steplessly, when the torque converting ratio can be changed in a smooth way according to the driving situations.

The solution according to the invention fulfils these requirements and tne physical foundation of its function is the converting of the motional energy quanta by means of the impulses into potential energy. The motional energy quanta are formed when the engine, driving the transmission, functions for a moment unloaded and the speed of its moving parts as well as the quantity of motional energy, based on it, grows. When the input shaft, driven by the engine, gets thereafter engaged to the middle shaft, the angle speed of this rises and becomes nearly equal to that of the input shaft and greater than the angle speed of the output shaft, which in¬ creases the torsional force of the spring located between the middle shaft and the output shaft- Thereafter the connection of the input shaft and the middle shaft gets disengaged and the same process begins from the beginning again. In this way the in¬ crease of.the motional energy quantity is converted by means of an impulse into torsional force i.e. an increase of the quantity of potentional energy and main¬ tains on the output shaft prevailing torque, which depends on the loading and may be for instance about 10-fold as compared to the average torque generated by the _ enFine A mechanical condition of the functioning of the solution according to the indention is a hydrostatic clutch located between the input shaft and the middle shaft by means of which the engagement of the input shaft to the middle shaft and its disnnraF*nent from it can take place rapidly enough without mechanically straining secondary effects. This is quite possible among others with the help of the variations shown in figures 1, 3 and 5 and can evidently be realized also with a magnetic clutch.

The profits of the solution according to the invention are the simple design as well as above all the technical properties such as the stepless function in a wide torque converting range. Mereover the solution selects automatically the converting ratio required by the loading on the output shaft, wherefore the com¬ plete automatization of the functioning is easy. This is based, when the engine throttling is unchanged, on the fact that when the torque converting ratio is growing as a result of the harder loading on the output shaft the number of im¬ pulses, in time unit, increases nearly in the same proportion but their duration time shortens correspondingly. Because of this, the quantity of energy transferred in time unit with the help on the clutch from the input shaft to the middle shaft and further to the output shaft will be nearly unchanged as well as the engine loading. Thus, if the position of the valves, which are controlling the function of the device are not changed, the loading variations on the output shaft will act upon the torque converting ratio and the revolution speed of the output shaft,but the influence upon the loading and the revolution speed of the engine is propor¬ tionally small. A complete automation is reached, when the functioning of the con¬ trol valves is synchronized with the variations of the engine performance and rev¬ olution speed as well as with the loading on the output shaft.

A noteworthy profit, as compared to conventional automatic transmissions, is among others the decisively better efficiency in the power transmission and also generally speaking a good efficiency at low converting ratio values due to the fact that there appear no gear wheel losses. On direct gear the losses are insignificant and due, in the first place, to the oil viscosity. On the other hand, each impulse causes losses, the amount of which depends on the quantity of oil flowing during the impulse through'the control valve and on the pressure difference. As, when the converting ratio is growing, the number of impulses per one revolution of the output shaft grows, the consequence of it is that the converting efficiency i. deterged as a function of th. torcue convenus ratio accordins to the follow- ing formula: CH _ n -- 1 - ~n where n = efficiency CR = torque converting ratio c - coefficient, depending on the construction The value of coefficient c, which also determines the «aXl.,un, value of the torque v tinsratio CB, depends in the first P-e on how ZT each revolution made by the input shaft in regard to the middle sha.t. ThJ«tests 1. with a prototyPe as per the variation sho» in Fig.! with two pulses fons 11.,. .ave he value o = 9.5, when the maxim» torque converting rat o -as rHh™,; «rimentall, W increasing the *-*,-« oulput'shaft until it sto. and the .«-J.» Tlos converting ratio , : 2 the efficiency was n = 0.89 and the influe is provable therein that the gearins ratio was then 2 _ - there.

e solution according to the variât,.>n ano» « * by, that the rotating movement of the inpu aha t n rag causes a momentary or continuous '"—*«*£' thot the pressure prevailing hydrostatic clutch into its pressure space m that way i„ the pressure space counteracts TZZ- - -—• «" thus -a motion between the inpu -- » th functioning mode of the clutcn D™ssure prevails in it.

flow from th. pressure space and in that way "»•*+££ and the device is ih When the control vaive is fully open « P™. is 0„ direct the neutrai position and when the valve is J is fo„ing gear. Between these limit ZZ* converting ratio is aes--;-; •-tlonandrarles- "» Itrperformance « revolution speed range of the engine.

" ' v*,. direct gear when a high enough basic pressure is main- The device „ on the direc gea tained ih the pressure space of the clutch in s pressure can be obtained for instance wth £ » limiting valve driven by the output shaft The val pressure in that way that the device is kept on the direct g torque required at the driving with different level speeds and increased by a suitable reserve. In case the loading rises steeply, caused for instance by a steep uohill, the formation of-the impulses begins automatically, which maintain the torque required by the loading on the output shaft whereat the revolution speed of the output shaft and the driving speed decrease. If, in this situation, the engine performance increases sufficiently,the revolution speed of the engine and the input shaft grows in regard to the revolution speed of the middle shaft to such an extent that the forming impulses transfer sufficient energy to the output shaft without a decrease of its revolution speed. In both cases, the device func¬ tions as a torque converter and steplessly.

The variation corresponding to manual transmissions is equipped with a valve group in which the main valve is manually controlled and when the engine is at idle running, an additional valve, regardless of the main valve control, keeps the device in neutral position.The engine is fitted with a revolution speed limiter.

The power transmission in the opposite direction is obtained with a one-way valve, which prevents the return flow of oil from the suction space of the clutch to the oil sump of the device. When the middle shaft has a greater revolution speed than the input shaft, oil is transferred from the pressure space of the clutch to its suction space and since the one-way valve prevents the oil flow from the suction space, the pressure rises in it until the middle shaft rotates the input shaft and the engine. The engine braking functions then and the engine can be started for instance by towing the car. Particularly in connection with the manually controlled variation there is reason to fit the device with a valve, which by..limiting the maximum pressure in the pressure space of the clutch limites the maximum value of the generated torque and in that way prevents the mechanical straining of the power transmission components to be too hard. There is reason to fit the device also with an auxiliary valve, the function of which is synchronized with the main control valve, and when this is in the extreme closing position, it prevents the flowing of oil from the pressure space of the clutch along other ducts except that, which is closed by the main control valve and keeps the device continuously on the direct gear irrespectively of the revolution speed and the loading of the engine.

The solution according to the invention is also extremely suitable for use on earth movinS échines and sindlar e.uxprnents, and , for instance, the sprang and hydrostatic clutch cognation .ay be used for S.OOthly starting Of heavy machine units in the industry.

Concerning the functxoning principle of the solution according to the invention it rnay generally be established that when the input shaft rotates in regard to the middle shaft, the construction ( the variation shown in Fig 1 ) causes the transferring of oil fro, the suction space of "the hydrostatic clutch to its pressure space and, when foxing an impulse, the oil flows from the pressure space through the control valve only, which is throttling .he .lowing.

the influence of the pressure on oil density is insignificant, the pressure rises then steeply in the pressure space of the clutch until it moving into it, which stops the moverBent between the clutch components and m variations the movement of the piston in the cylinder causes a corresponding effect The torque, generated by the engine, turns then the middle shaft in direction of the power transmission and increases the torsional force in the spring located beween the middle shaft and the output shaft. The duration time of the impulse and the turning angle of the middle shaft during the impulse depend on the control valve position and on the torque level prevailing on the raiddle shaft and caused by the loading. The greater the torque t h gh the pressure pea* in the clutch and the greater the flowing speed of oil through the control valve at the determined control valve position, which means a shorter deration time of the impulse and greater gearing and torque covertmg ratios.

in the variation shown on FiS. 1 the parts 3, 5 and 6 form'the hydrostatic .

clutch whose centre gear 3 is a part of the input shaft 1 and the clutch housin, 6 is a part of the middle shaft 17, which by means of the spring 16 rotates the output shaft 22 The one-way clutch 9 prevents the turning of the middle shaft 17 .0 .he opposite direction in regard to power transmission- In the centre gear 3 has oeen formed the groove U and the necks 28 shown on Fig.2. The oil duct T opens as well to the pressure space of the clutch as to the groove * and links these to the con¬ necting pipe 10. Oil duct 8 opens to groove 4 and links it to connecting pipe 11.

Oil duct 13 linKs the connecting pipe 2U to the suction space of the clutch, «hen the centre gear is rotating in regard to clutch rousing. 6 the side gear routes in opposite direction and the clutch sucks oil from the connecting pipe 24 whicn is linked to the oil sump of the device. The connecting pipe 10 is linked to the control valve 55 Fig. 4 and from connecting pipe 53 the oil flows to the oil sump of the device.

When the centre gear rotates in regard to clutch housing 6 and the neck 28 reaches the orifices, where the oil ducts 7 and 8 open into the groove 4, the flow of oil from pressure space to oil duct 8 is prevented and the oil flowing takes place exclusively along oil duct 7 to connecting pipe 10 and further to the control valve 55 On the control valve position depends the flowing resistance and the pressure loss caused by it and, as a function of the difference in angle speed between the input shaft and the middle shaft, it determines how high pressure peak prevails in the pressure space of the clutch during the impulse. The greater the angle speed difference and/or the torque, caused by the loading and prevailing on the middle shaft, the higher the pressure peak and greater the torque which durons ' the impulse turns the clutch housing 6 towards the power transmission.For realizing a fully automatic function, the output shaft 22 is equipped with oil pump 20, from which the oil flow leads to the connecting pipe 57 in the control valve 5 Fig- 4.

The oil pressure is determined by a pressure limiting valve, which is controlled by the revolution speed of the output shaft and in different driving conditions maintains a proper basic pressure in the clutch.

In the variation shown on Fig. 5 the hydrostatic clutch xs formed by a disk-like piston 63, which is eccentric in regard to input shaft 61, a bottom - 7 plate 66 and the cylinder 64, which is in a pivoting way bearing-mounted in point 65 in the section A — A* FiS. 6 is visible the orifice of the oil duct 71, which opens to the cylinder space 60 and is continuously open, as well as the orifice of the oil duct 67, which is closed in the extreme position of the cylinder 64. In this position are formed the impulses and the valve, in which the oil leads from the orifice of duct 71, controls the function of the device. On Fig- 3 xa shown a variation, in which the .oven.ent of the piston 47 takes place in axial direction.

The sliding rods 41 and the rod guides 40 and 42 prevent the turning of the pis.on towards the input shaft 30- The impulse forms when the bulge in the piston meets the bulge 43 in middle shaft and the piston tends to move to the left on the .igure.

From the connecting pipe 34 oil leads to a valve, which is controlling the function of the device. After the impulse the spring 37 returns the piston to the initial position and oil flows in the pressure space 46 through the connecting pipe ,2, which is linked to the oil sump of the device.

in all variations the pressure limiting valve, which is determining uhe maximum pressure level prevailing in the pressure space of the clutch, is linked for instance to the connecting pipe 57, Fig. 4.

It is obvious that the invention is not limited to the aforementioned examples of application and that many other constructions can be put forward according to the following patent claims.

Fig- 1- Fig. 3- 1 = input shaft Fig- 2. 3 = centre gear 2 = main bearing 4 = groove 3 = centre gear 26 = neck 4 = groove = side gear 6 = clutch housing Fig. 4. 51 = valve lever 7 = oil duct 52 = valve port 8 = oil duct 53 = connecting pipe 9 = one-way clutch 54 = connecting pipe = connecting pipe 55 = valve housing 11 = connecting pipe 56 = valve spindle 12 = oil delivery component • 57 = connecting pipe 13 = oil duct lit = spring fixing point = bearing Fig. 5- 60 = pressure space 16 = spring 61 = input shaft 17 - middle shaft 62 = main bearing 18 - bearing 63 - piston 19 = main bearing 64 = cylinder = oil pump 65 = bearing 21 = main bearing 66 = bottom plate 22 = output shaft 67 = oil duct 23 = bearing 68 = bearing 2H = connecting pipe 69 = one-way clutch = spring fixing point 70 = middle shaft 26 = connecting pipe 27 = connecting pipe Fig. 6. 63 = piston 64 = cylinder = input shaft 65 = bearing 31 = one-way valve 66 = bottom plate 32 = connecting pipe 67 = oil duct 33 = main bearing 71 = oil duct 34 = connecting pipe = oil duct 36 = main bearing 37 = oil duct 38 = cylinder wall 39 = spring HO = rod.guide 41 = sliding rod 42 = rod guide 43 = bulge 44 = one-way clutch = middle shaft 46 = pressure space 47 = piston /ru 107403 The embodiments of the invention in which an exclusive property or privilege is claimed, are defined as foilows:

1- A torque converting device which comprises; an input shaft driven by an engine; an output shaft for driving a load; a middle shaft intermediate said input and output shafts ; clutch means for transferring energy quanti from said input shaft to said output shaft in the form of a series of impulses wherein the number of impulses for a time unit is proportional to the difference between the revolution speeds of the input shaft and the output shaft and a torque larger than the average torque generated by the engine acts on said output shaft; and said clutch means engaging and disengaging said input shaft to and from said middle shaft with the momentary or continuous torque being transferred being a function of the pressure level acting in a pressure space of the clutch and with the torque being converted by the device increasing or decreasing in the same proportion as the pressure level in the pressure space rises or drops.

2. Device according to claim 1 further characterized thereby in that per each revolution made by the input shaft with respect to the middle shaft there is at least one inter-shaft position in which the oil flow from the pressure space of the clutch means is prevented along ducts other than ducts for conducting oil to valves, whereby the pressure level acting in the pressure space of the clutch means is controlled by throttling the out-flowing of oil.

3- A device according to claim 1 wherein:

said clutch means comprises a hydrostatic clutch having a housing located between the input shaft and the middle shaft, a center gear, a pressure space and a section space ; said housing forms part of a first one of said imput and middle shafts; said center gear forms part of a second one of said (0