US2260015A - Hydraulic device for transmitting power - Google Patents

Description

Oct. 21, 1941. R. FICHTNER 1 HYDRAULIC DEVICE FOR TRANSMITTING POWER Filed July 8, 1938 2 Sheets-Sheet 1 Inventor": Rudolf lichtner,

His Attorney.

R. FICHTNER HYDRAULIC DEVICE FOR TRANSMITTING POWER Filed-July 8, 1938 2 Sheets-Sheet 2 Inventor:

Rudolf Fichtner", by $22 2% His Attorney.

E'EZDRAULIC DEVICE FOR TRANSMITTING PGWER litudoir Fichtner, Berlin, Germany, assignor to General Electric flompany, a corporation of New York Application July s, 1938, Serial No. 218,252 in Germany July 16, 1937 1 (Claim. (Cl. {MD-54) torque converters of the Fottinger type, consisting primarily of impeller wheel and one or more fluid impelled wheels mounted in a common casing in which a fluid is circulated to transmit power between the wheels.

Torque converters of the above mentioned type,

described in detail in U. S. Patent 1,199,359, re-

quire a series of stationary guide vanes for the purpose of producing a difierence between the input and output torques. In multi-stage devices, several of these guide vanes are required, and more specifically the required number of such vanes is equal to one less than the number of stages in the devices.

An' exception to the above stated rule is in devices wherein several impelled turbine wheels run in opposite directions, such operation being obtained partly by repulsion between the two pairs of oppositely running wheels. While in such devices the algebraic sum of the output torque is equal to the input torque, it is possible for the absolute values of these torques to varyfrom each other substantially.

In both types of converters; that is, the impulse type in which both input and all output wheels run in the same direction, and the repulsion type, in which the output wheels run in opposite directions, the fluid returns fromthe turbine, or impelled wheel, directly to the intake side of the impeller wheel. The circulation of this fluid entering the impeller wheel (entry whirl) is substantially affected by the speed of rotation of the last turbine wheel. As a result of this characteristic, the impulse type of device impact losses between the oppositely running turbine wheels. At standstill, that is at the starting period when the turbine wheel is at rest, the speed of this fluid impact-is equal to the sum of the peripheral speeds of the oppositely running wheels during impact-free operation whereby the loss dueto this impact is approximately proportional to the square of the impact speed.

One object of my invention is to reduce the impact losses and thereby increase the efiiciency of hydraulic couplings of the above described type.

For a better understanding of my invention together with other and further objects thereof,

reference is had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claim.

In the accompanying drawings, Fig. l is a diagrammatic cross-sectional view of a standard form of hydraulic torque converter; Fig. 2 is a graph illustrating the speed and torque characteristics of this type of converter; Figs. 3, 5, '7 and la are diagrammatic cross-sectional views of hydraulic converters which are modifications of the coupling shown in Fig. 1, made in accordance with my invention, and Figs. 4, 6, and 8 are graphs illustrating the speed and torque characteristics of the modified converters illustrated in Figs. 3, 5, and 7 respectively.

Referring to the drawings in detail, Fig. '1 illustrates a coupling comprising an impeller wheel l driven by a shaft 8 and operating at a speed of m. The turbine wheel 9 mounted on a hollow shaft ill and a second turbine wheel ll mounted on a shaft l2 are driven by a fluid circulated in planes at right angles to the axis of rotation by the arcuate vanes 33 of the impeller wheel. The turbine wheels 9 and H are provided with complementary vanes M and i5, respectively, to form a single fluid circulating path, and operate in opposite directions to each other; turbine wheel 9 operating in the same direction as the impeller wheel 1, and turbine wheel I! operating in the opposite direction to the impeller wheel 1. The hollow shaft it drives a,shaft lll' through a gearing ill". The speed of the turbine wheel 9 is m and the speed of the turbine wheel H is equal to m or varies slightly therefrom.

Fig. 2 discloses a set of curves of which 1; (eta) indicates the efliciency of the converter, curve N1 indicates motor load, performance, or utilization; and the line M2 indicates the output torque at various speed relations between the impeller and impelled wheels. For plotting'the output torque the ordinate unit chosen is the torque developed at 1 The abscissae unit is the quotient of "1 and in view of the fact that when i unit which may be called the normal running torque.

In accordance with my invention, stationary .guide vanes are provided in the repulsion type devices, in which such vanes are not ordinarily needed for torque conversion, and in the provision of one or more sets of stationary auxiliary guide vanes in torque converters in which such vanes are ordinarily provided. I

In all forms of the device; that is, the, impulse and the repulsion forms, one set of stationary guide vanes is, in accordance with thisinvention, preferably placed in front of the impeller inlet. The impeller is thereby freed of the influence oi the rotation of the turbine wheel and its performance remains practically independent of the output speed. The power of the prime mover, for example, the motor of a vehicle, is thereby fully utilized. In cases, and specially in the case of the repulsion converters, an increase of the starting torque is thereby obtained.

If in the case of repulsion converters, a set of stationary guide vanes is provided between the oppositely running turbine wheels in addition to, or in place of, the set of stationary vanes at the entrance to the impeller wheel, the above men- 'tioned impact losses between the oppositely running turbine wheels are substantially reduced. This is due to the fact that the impact speed is thereby divided into two parts, and since the total loss at the impact points is proportional to the sum of the squaresoi its parts, the loss, at equal .speeds, is only one-half as great as in the case where no stationary vanes are provided.

Fig. 3 is a diagrammatic sectional view of a torque convermr such as shown in Fig. l modified.

hi accordance with my invention. In this modification, the converter includes an impeller wheel it mounted on a shaft ii, a turbine wheel it mounted on a hollow shaft is, and a second tur= bine wheel 2t mounted on a shaft 2i arranged,

to run in a direction opposite to that of the wheel it. The impeller wheel and turbine wheels are provided with vanes 22, 23, and 26, respectively, arranged for circulating the fiuid between them. In this modification a set or stationary vanes 25 is provided containing a series of vanes 25 which guide the fiuid discharged from the vanes 23 of the first turbine wheel into the vanes 25 of the second turbine wheel 2d. The turbine shaft is is geared to drive a shaft It through gearing ill". Fig. 4 discloses the characteristics of this modified converter. It will be noted that the starting torque has been raised to a value of 4.25 times the normal running torque and the efficiency curveis somewhat improved. This improvement is traceable to the decrease of the fiuid impact losses accomplished by the use of the stationary intermediate vanes between the turbine wheels it and 20. The performance, or load, curve N1 does not vary, materially, from that of Fi 2.

In Fig. 5 another modification of my invention is shown. This figure illustrates in vertical crosssection a converter provided with an impeller wheel 21 mounted on a shaft 28, a turbine wheel as mounted on a shaft 36, and a second turbine wheel ti mounted on a hollow shaft 32 which is geared to shaft it by gearing lil". The impeller wheel and the turbine wheels are provided respectively with vanes 33, 34, and 35, arranged to circulate fluid between them, and the two turbine wheels operate in opposite directions to each other. In the present modification, a set of stationary vanes 36 is provided having a seriesoi vanes 3? which guide the circulating fluid from the discharge end of the turbine vanes to the intake side of the impeller vanes 33.

Fig. 6 discloses the characteristics of the modification of-Fig. 5. The first substantial change is in the performance or load curve N1 which is substantially constant. This'is traceable to the ad= dition of the stationary guide vanes at the entrance to the impeller vanes. The starting torque in this instance has increased to 4.4 times the normal running torque. The efilciency curve remains substantially the same as in the previous modifications.

In'Fig.'7 l. have illustrated a third modification of the torque converter. In this figure a diagrammatic cross-section of a torque converter is illustrated including an impeller wheel 46 mounted on a shaft 69, a turbine wheel 62 mounted on a hollow shaft 43 and a second turbine wheel I mounted on a shaft 65. The impeller and turbine wheels are provided with vanes d6, 61, and 48 respectively and the two turbine wheels are arranged to run in directions opposite to each other.

The shaft 43 is geared to a shaft ID by gearing it". In accordance with my invention, this modification is provided with a stationary guide apparatus 69 provided with two sets of guide vanes 56 and 5G. The vanes 50 are placed be tween the discharge side of the first turbine A wheel and the entrance to the second turbine wheel, while the second set of stationary vanes "59 is placed between he discharge side ofthe second turbine wheel M and the entrance to the impeller wheel Mi. This modification -thereby possesses the advantages of the two modifications of Figs. 3 and 5. I

Fig. 8 discloses the operating characteristics of this modification. The performance, or load, curve N1 is substantially constant as in the modification of Fig. 5 and the starting torque is increasedto 5.3 times the normal running torque. The efficiency curve 1 (eta) is also, as in Fig. 4, raised and extends ,over a larger range of the values Fig. 7a. is a modification of the arrangement shown in Fig. 7, the turbine wheels t2 and 58 being arranged to operate in the same direction. instead of in opposite directions, as shown in Fig.

.7. This is indicated by the arrows indicating containing circuit which consists of an impeller wheel, a pair of turbine wheels coaxially arranged with respect to each other and with respect to the impeller wheel, the vanes of said turbine wheels being so arranged that the said turbine wheels rotate in opposite directions with respect to each other and a set of stationary vanes arranged on the entrance side of said impeller wheel to receive thefluid discharged by said tur-' bine wheels and to return it to said impeller wheel and another set of stationary vanes arranged between the said two oppositely rotating turbine wheels to guide said fluid therebetween.

RUDOLF FICHTNER.

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