EP0034958A2 - Engine with rotary pistons having a cyclic speed variation and driving means - Google Patents

Abstract

Internal combustion rotary volumetric motor, comprising a fixed casing delimiting an annular space in which are mounted in the same direction rotary pistons which are diametrically connected in pairs by means of an arm and driven by a cyclic speed variation causing a variation of volume of the space delimited by the radial faces of the pistons. The annular space in which the pistons (3, 3a, 4, 4a) move is delimited by the casing (1) and a rotary crown (2) having lights in which the arms (5, 6) are engaged and which allow an annular movement of the arms (5, 6) for bringing the pistons (3, 3a, 4, 4a) closer and further away. This rotary crown (2) is connected on one side by a transmission means to the shafts (27, 28) which are integral with the arms (5, 6) carrying the pistons (3, 3a, 4, 4a) and the other side to the output motor shaft. This transmission means consists of two rod-crank systems (26, 25, 26a, 25a) each connected on the one hand to one of the shafts (27, 28) and on the other hand, thanks to an eccentric pin (24, 24a) to a pinion (22, 22a), mounted on an axis (23, 23a) carried by the rotary crown (2) and meshing with a fixed outer crown (20).

Description

The present invention relates to an improvement to rotary positive displacement motors.

• - les moteurs à flux continu du type à turbine à gaz qui fonctionnent suivant le cycle de Joule ;
• - les moteurs volumétriques où la compression et la détente sont obtenues par variation de volume et qui fonctionnent suivant le cycle Beau de Rochas (moteurs à essence) ou Diesel.

Among the thermal engines which transform the thermal energy supplied by the fuel into mechanical energy, two main classes of engines must be distinguished:

• - continuous flow motors of the gas turbine type which operate according to the Joule cycle;
• - volumetric motors where compression and expansion are obtained by variation in volume and which operate according to the Beau de Rochas cycle (petrol engines) or Diesel.

• - les moteurs à flux continu ont sur les autres l'avantage de la légèreté, ce qui les fait généralement préférer pour les moteurs aéronautiques, mais ont une consommation spécifique élevée, de l'ordre de 200 g par cheval/heure pour les grosses turbines à gaz, chiffre qui peut monter à 300, voire plus, pour les turbines à gaz de petites dimensions ;
• - les moteurs volumétriques à essence et Diesel sont lourds et encombrants, inconvénient grave mais généralement acceptable pour les moteurs terrestres du fait de leur consommation spécifique faible (les moteurs Diesel peuvent avoir des consommations spécifiques de l'ordre de 150 G par cheval/heure).

None of the motors belonging to these two classes is perfectly satisfactory:

• - continuous flow engines have the advantage of lightness over others, which generally makes them prefer for aeronautical engines, but have a high specific consumption, of the order of 200 g per horse / hour for large turbines gas, a figure which can rise to 300 or even more, for small gas turbines;
• - Volumetric petrol and Diesel engines are heavy and bulky, serious drawback but generally acceptable for land engines due to their low specific consumption (Diesel engines can have specific consumptions of the order of 150 G per horse / hour) .

The differences in specific consumption between the continuous flow and volumetric motors mentioned above correspond to the maximum continuous speed of the two types of machine. These differences are further increased if we consider the partial regimes where the DC motors have a specific consumption which increases quickly when the load is reduced, Diesel engines, on the contrary, having a specific consumption that is little different and sometimes even improved, when the load is reduced.

The analysis carried out by the applicant on this subject led to the following remarks from which the invention derives.

One of the first reasons for the low consumption of volumetric motors is precisely that compression and expansion take place volumetrically, which means that the compression and expansion yields are very close to 1. As a first approximation to the rest, it is generally considered that compression and expansion are isentropic. On the other hand, compression and expansion in a continuous flow motor are done with a clearly different efficiency from 1.-Despite the progress made since the birth of turbomachines, the compression efficiency is around 88% and that of relaxation of around 90%. These figures are only valid for large turbomachines (and for a narrow range of their operation), while small turbomachines (or large ones outside this range) have yields even further from the unit yield of compression and rebound almost achieved by Diesel engines.

It is a first object of the present invention that compression and relaxation are done volumetrically, in order to bene ~ ficier yields very close to the unit allowed by this type of compression or relaxation.

On the other hand, the low consumption of positive displacement motors is also due to the fact that the effective temperature to be taken into consideration in the cycle is practically very close to the stoichiometric temperature. This temperature is acceptable for neighboring parts (cylinder, cylinder head and pistons) in particular because this temperature is a maximum temperature reached during a very small fraction of the duration of the complete cycle so that the parts, mobile or stationary moreover, do not have time to heat up during this fraction of the time and would tend, even in the absence of cooling, to take a much lower temperature.

For continuous flow motors, on the contrary, and the fact that parts, fixed and above all mobile, are permanently subjected to the temperature of the flow which bathes them (instead of being subjected to various temperatures with a very high tip but of short duration, and a variable temperature but always much lower in quasi-permanence), one is forced to limit, in the current state of metallurgical knowledge, the maximum temperature of end of combustion chamber. Even if locally the stoichiometric temperature is reached in the combustion chamber, the effective temperature, that is to say that which conditions the efficiency of the cycle, is much lower.

It is one of the aims of the present invention to permanently allow an effective temperature of the cycle close to the stoichiometric temperature.

The two advantages of the invention set out above already exist in other engines, in particular diesel engines. However, these have the disadvantage of being heavy and bulky as can be appreciated by the remarks below.

A conventional diesel engine notably includes a connecting rod which transmits the forces coming from either gases on the crankshaft (this is the engine force during expansion), or the force of the crankshaft on the gases (this is the force for compression during this phase). Considered on the same cylinder, these forces are shifted in time and it is necessary to calculate the resistance of the parts (connecting rods, crankshaft pin, etc.) for the maximum forces. without possible compensation, therefore to size them for these maximum forces although in fact they are successively directed in opposite directions to each other. One could also say that for a multicylinder the dimensioning of the parts must take account of the maximum effort individually for each set cylinder, connecting rod, crankpin, crankshaft without possible compensation to lighten the set, although there is, in engine torque (therefore at the output of the crankshaft) compensation since the compression gives a resistant torque. Each connecting rod in particular must be calculated and dimensioned for the maximum effort (at the start of combustion).

It is one of the aims of the invention, while retaining the advantages of the cycle and therefore of the specific consumption of the diesel engine, to avoid these drawbacks by a provision allowing the compression and expansion forces to be compensated internally.

Also, one of the limits of the power available for positive displacement engines is due to the problem of their air supply (fueled or not), due to the relative smallness of the valves or the intake lights. In the case of valves for example, they are generally housed in the cylinder head (noting, moreover, that their control by camshaft, if necessary rocker rods, rocker arms themselves, also increases the complication, the bulk and the mass). However, taking into account that the cylinder head must also include the ignition system and / or the injection system, the area available for the valves is generally a limiting criterion for the engine rotation speed. The throttling produced by the valves is, moreover, one of the causes of the drop in power which occurs at high speed of rotation of such engines. Volumetric motors of the prior art therefore have, due to the difficulty of supply, due to the impossibility of increasing the cross-sections of the intake valves, a large mass per unit of power.

It is one of the aims of the present invention to provide a solution to this feeding problem by means of an intake of dimension much larger than the intake sections used in the prior art.

In addition, the Applicant has formerly carried out tests which have shown that the friction of the pistons and their packing is higher at top dead center and at low dead center than in the middle of the race for reciprocating piston engines. In fact, what is at issue is not that the piston is at a top or bottom dead center, it is that it is stationary relative to the casing. Each time it is stationary, the oil film which makes it possible to reduce this friction (generators of loss and especially of wear) is broken, which limits, despite all the progress made, the lifetime of the positive displacement motors. prior art.

It is one of the aims of the present invention to allow a positive displacement motor to have, in operation, no temporary stopping of the pistons relative to the outer casing.

Finally, it should be noted that the specific consumption advantages of diesel engines over continuous flow engines in the consumption aspect only exist in their entirety in the case of four-stroke diesel engines.

For the comparison of diesel engines and the present invention, it is therefore this case that must be considered. For example, for a 4-cylinder Diesel engine, there are two engine times per revolution, or, in another form, we can say that each cylinder has one engine time per two revolutions. It is one of the objectives of the present invention to allow, for the benefit of the bulk, the mass, the number of parts, and the cost, that there are four engine times per revolution.

There are also known rotary volumetric motors comprising a fixed casing delimiting an annular chamber in which pistons are rotatably mounted in the same direction, which are diametrically connected in pairs by means of an arm and driven by a cyclic speed variation generating a variation in volume of the space delimited by the radial faces of the pistons, said pistons spaces between the pistons constituting chambers of an engine operating on a four-stroke cycle.

• - dans tous les cas, le mécanisme de récupération de la puissance, par un système de bielles ou de cames, est lourd et encombrant, notamment du fait que la compensation interne des efforts n'est pas ou n'est que partiellement assurée ;
• - de plus, dans tous les cas, l'admission et l'échappement d'air sont étranglés dans des conditions analogues à celles des moteurs à piston alternatif ;
• - enfin, certains d'entre eux comportent des carters tournants, et/ou deux chambres de travail au lieu de quatre, etc...

However, known motors of this type are not entirely satisfactory because:

• - in all cases, the power recovery mechanism, by a system of connecting rods or cams, is heavy and bulky, in particular because the internal compensation of the forces is not or is only partially ensured;
• - moreover, in all cases, the air intake and exhaust are throttled under conditions similar to those of reciprocating piston engines;
• - finally, some of them have rotating casings, and / or two working chambers instead of four, etc ...

In accordance with the present invention, the annular space in which the pistons move is delimited by the casing and a rotary crown presenting lights in which the arms are engaged and which allow an angular movement of the arms for the bringing together and the distancing of the pistons, said crown constituting or being connected to the output drive shaft and being connected by a transmission means to the shafts which are integral with the arms carrying the pistons. In this way, unlike the rotary volumetric motors of the prior art, the assembly of the motor according to the invention is light and of reduced bulk, and of a safe operation and without jamming possible.

Note that the motor shaft can be either on one side or the other of the rotary positive displacement motor.

However, it has been found, with the device described above, an irregularity of the torque applied to the pinions during operation.

FIG. 4 shows a diagram on which the angle of rotation of the pinions is shown on the abscissa and the motor torque applied to the pinions is shown on the ordinate. Curve 31 represents the evolution over the cycle of the engine torque which increases, passes through a maximum, decreases, cancels, reverses (becomes resistant during compression), becomes zero again and this twice per revolution.

When the torque is inverted, there is a toothing which risks causing the gears to deteriorate.

To overcome this drawback, a motor is used in which are arranged along the same axis and symmetrically two modules offset by 90 ° taking as a reference the angle of rotation of the pinions.

As described above, each module has two rod-crank systems connecting each pair of pistons to each pinion, but in the combination of the two modules, the two pinions are common and the two rod-crank systems coming from each module and actuating the same pinion are offset by 90 ° (taking as a reference the angle of rotation of the pinions).

An assembly is thus obtained, the regularity of the torque of which is equivalent to that of a sixteen-cylinder four-stroke engine which has eight engine times per revolution.

There is shown in Figure 5, a diagram with the same coordinates as in Figure 4 and on which are represented two curves 31 and 32 which are offset by 90 ° and which represent the evolution of the motor torques applied to the pinions of a pair of associated motors.

It can be seen that at all times, if the sum of the motor or resistance torques, as the case may be, represented by curves 31 and 32, the value of the average resulting torque 33 is practically constant.

• - la figure 1 est une vue en coupe transversale d'un mode de réalisation du moteur rotatif suivant l'invention ;
• - la figure 2 est une vue simplifiée en coupe longitudinale d'un mode de réalisation du moteur rotatif suivant l'invention, chaque sous-ensemble étant ramené dans le même plan ;
• - la figure 3 est une vue montrant schématiquement la disposition dans le sens transversal des moyens de liaison entre les bras portant les pistons et les moyens de transmission de puissance ;
• - la figure 4 est un diagramme représentant le couple d'un moteur à un seul module en fonction de l'angle de rotation des pignons ;
• - la figure 5 est un diagramme représentant les couples des deux modules du moteur en fonction de l'angle de rotation des pignons ;
• - la figure 6 est une vue en coupe longitudinale du moteur constitué de deux modules.

Other characteristics and advantages of the invention will be better understood on reading the following description of an embodiment and with reference to the appended drawings, in which:

• - Figure 1 is a cross-sectional view of an embodiment of the rotary motor according to the invention;
• - Figure 2 is a simplified view in longitudinal section of an embodiment of the rotary motor according to the invention, each sub-assembly being brought back in the same plane;
• - Figure 3 is a view schematically showing the arrangement in the transverse direction of the connecting means between the arms carrying the pistons and the power transmission means;
• - Figure 4 is a diagram showing the torque of a single module motor as a function of the angle of rotation of the pinions;
• - Figure 5 is a diagram showing the torques of the two engine modules as a function of the angle of rotation of the pinions;
• - Figure 6 is a longitudinal sectional view of the engine consisting of two modules.

In FIGS. 1 and 2, a rotary volumetric motor is shown according to the invention which comprises a fixed external casing 1 limiting an annular space, on the one hand peripherally, on the other hand on its front and rear faces.

The housing is shown in a single element in the drawings, for the purpose of simplification, but, of course, it includes the number of elements necessary to allow mounting.

Inside the casing 1 is arranged a rotary crown 2 which internally delimits this annular space in which move in rotation in the direction of the arrow F four pistons 3, 3a and 4, 4a. The pistons 3, 3a are symmetrical and connected by means of an arm 5 and the pistons 4, 4a are also symmetrical and connected in the same way by an arm 6. The arms 5 and 6 are respectively made integral with the shafts 27 and 28 by a key (not shown) or any other known means ...

The annular space, in which the pistons move, may have a quadrangular cross section as shown in Figure 2, or circular, for example in the simplest cases, or any combination of circular sectors and line segments in particular.

The radial faces 7, 8 of the adjacent pistons delimit between them spaces 9, 10, 11, 12 of variable volume which correspond to the chambers of an engine operating according to a four-stroke cycle.

The assembly constituted by the crown 2 and the pistons 3, 3a and 4, 4a is driven according to the same general rotary movement according to the arrow F, while the pistons 3, 3a and 4, 4a are further animated, as will be explained below, of a cyclic speed variation corresponding to a movement of acceleration and deceleration of each arm 5, 6 which causes an approximation and an alternative distancing of the pistons 3, 3a and 4, 4a in order to obtain a variation in cyclic volume of the spaces or chambers 9, 10, 11, 12 enabling a four-stroke cycle to be carried out. In the position shown in Figure 1, the chamber 9 is in the intake phase, the chamber 10 in the compression phase, the chamber 11 in the expansion phase and the chamber 12 in the exhaust phase. In this way, the force necessary for the compression which is exerted on one face of a piston is provided by the work of relaxation of the gases, which is exerted on the other face of the piston, therefore passes directly from the one to the other, which avoids the increase in mass and / or bulk which would exist if the last effort had to be transported by the connecting rod and by the corresponding crankpin and then by twisting the crankshaft, by a second crankpin, etc ..., then by another piston rod in the compression phase, as happens with volumetric reciprocating piston engines.

The ignition of the fuel mixture occurs when one of the chambers, in particular the chamber 10, is opposite the spark plug 13 which is mounted on the casing 1. Note that, in the case where the engine would operate according to a Diesel cycle, the spark plug 13 is replaced by a fuel injector.

The casing 1 also has a light 14 for the admission of the combustible gas mixture in the case of an ignition engine or fresh air in the case of a diesel cycle and a light 15 for the exhaust of the gases. burned.

In order to allow the angular movement of the arms 5 and 6 for bringing the pistons closer and further apart, the rotor ring 2 includes slots 16, 16a and 17, 17a.

To seal between the fixed outer casing 1 and the inner rotating ring 2 and the side faces when they exist on the one hand and the pistons 3, 3a and 4, 4a on the other hand, these are provided with seals 18, 19. Figure 1 shows a single seal at each end of the pistons but well heard there may be several in series. In the case of a circular section of the casing, the joint plane between the fixed part 1 and the rotary crown 2 is located at the mean diameter of the torus. In the case of a rectangular section, the outer casing may have three faces and sealing segments are placed in the connection zone of the inner rotary ring 2.

The angular displacement of the pistons and their developed length are determined by the choice of the volumetric compression ratio to be achieved. We deduce the necessary dimension of the lights 16, 16a, 17, 17a in the crown 2 for the displacement of the pistons. The intake and exhaust ports can advantageously have the developed length corresponding to the maximum spacing of the pistons and the maximum width compatible with the fixed casing.

The mechanical power produced at the level of the pistons is recovered on a shaft linked to the crown 2, by a "squirrel cage" 29, by means of a transmission device which comprises a fixed outer crown 20 (see FIGS. 2 and 3 ) having an internal toothing 21 with which mesh two pinions 22, 22a having a number of teeth equal to half that of the crown 20; These pinions 22, 22a are located in different planes and they do not mesh with each other. On the "squirrel cage" 29 integral with the crown 2 are provided axes 23, 23a diametrically opposite on which the gears 22, 22a are rotatably mounted and to which is connected by a crank pin 30, 30a an eccentric axis 24, 24a on which is articulated at one end of a connecting rod 25, 25a, the other end of which is articulated on another crank pin 26, 26a. The crank pins 26, 26a are respectively integral with the shafts 27, 28 which carry the arms 5 and 6 driven by the pistons 3, 3a and 4, 4a.

At each active gas combustion phase, during which the pistons move away, each pinion 22, 22a is driven by the corresponding connecting rod 25, 25a in the direction of the arrow F1. The axes of the pinions being integral with the crown 2, and due to the engagement of the pinions 22, 22a on the fixed outer crown 20, the crown 2 rotates along the arrow F2 (therefore in the opposite direction of rotation, pinions 22 and 22a on themselves), as well as the output shaft to which the motor force is applied.

Correlatively, the articulated system of the three-bar type, constituted by the crank pins 30, 30a, the connecting rods 25, 25a and the crank pins 26, 26a is dimensioned so that the complete rotation of the crank pins 30, 30a around their axis 23, 23a causes an alternating oscillation movement of the crank pins 26, 26a and therefore of the pistons between two extreme positions determined by the volumetric compression ratio chosen.

Because the pinions 22, 22a have a number of teeth half that of the crown 20, this alternating oscillation movement occurs twice per revolution of the rotary crown 2 (therefore of the output shaft) producing a movement bringing the pistons closer and farther twice a turn.

Figure 6 is a longitudinal sectional view of the motor consisting of two modules arranged in the same casing 1, along the same axis, but angularly offset by 90 °, taking as reference the angle of rotation of the pinions.

Each module is identical to that described above which is shown on the left with the same references while the right module which has been added has the same references but increased by a hundred.

Each module comprises two pairs of pistons (of which only one piston is shown) 3, 4 and 103, 104 connected radially in pairs by means of two arms 5, 6 and 105, 106 and moving in an annular space delimited by the casing 1 and a rotary crown 29 and 129 constituting the output drive shaft 2 and 102. The rotary crowns 29 and 129 are connected together to form a single assembly and they are connected by a transmission means to the four shafts 27, 28, 127 , 128 which are integral with the arms 5, 6, 105, 106 carrying the pistons.

The transmission means comprises two pinions 22, 22a common to the two modules which mesh with a ring gear 20 provided in the casing 1, each pinion 22, 22a is wedged respectively on a shaft common to the two modules 23, 123a and 23a, 123. The pinions 22 and 22a, common to the two modules, are between two radial walls 29a and 129a, one belonging to the left module, the other to the right module and forming part of the common assembly 29-129. The shaft 23, 123a is connected by a connecting rod 25 to the crankpin 26 of the external shaft 27 and by a connecting rod 125a to the crankpin 126a of the internal shaft 128.

Furthermore, the shaft 23a, 123 is connected by a connecting rod 25a to the crankpin 26a of the internal shaft 28 and by a connecting rod 125 to the crankpin 126 of the external shaft 127.

The crank pin 26a associated with the shaft 23d and the crankpin 126 associated with the shaft 123 which drive the pinion 22a are angularly offset by 90 °.

Similarly, the crank pin 26 associated with the shaft 23 and the crank pin 126a associated with the shaft 123a which drive the pinion 22 are angularly offset by 90 °.

Of course, various modifications can be made by those skilled in the art to the device which has just been described without departing from the scope of the invention, and in particular by replacing the fixed outer ring 20, on which the two pinions mesh, by a fixed toothed wheel carried by the casing, on which two planetary gears would mesh, having a number of teeth half that of the fixed toothed wheel and fixed in two points diametrically opposite to the rotary crown 2. 0n can also shift the average position of the crank pins 26, 26a for example 90 ° instead of being diametrically opposite, in their average position, as shown in the accompanying drawings.

Claims (15)

1. Volumetric internal combustion rotary engine, comprising a fixed casing delimiting an annular space in which are rotatably mounted in the driven direction of the pistons which are diametrically connected in pairs by means of an arm and driven by a cyclic speed variation generating a variation in volume of the space delimited by the radial faces of the pistons, said spaces between the pistons constituting the chambers of an engine operating according to a four-stroke cycle, the annular space in which the pistons move being delimited by the casing and a rotary crown presenting lights in which the arms are engaged and which allow an angular movement of the arms for the bringing together and the distancing of the pistons, said crown constituting or being connected to the output drive shaft, characterized in that the rotary crown (2) is connected by a transmission means to the shafts (27, 28) which are integral with the arms (5, 6) carrying the pistons (3, 3a, 4, 4a). 2. Motor according to claim 1, characterized in that the rotary crown (2) flourishes in a squirrel cage and comprises two diametrically opposite axes (23, 23a) on which are mounted, rotary, two pinions (22, 22a ) longitudinally offset which mesh with the internal toothing (21) of a fixed outer crown (20), each of the pinions (22, 22a) having a number of teeth equal to half that of the crown (20), each of pinions (22, 22a) also carrying an eccentric axis (24, 24a) relative to its axis of rotation, and on which is articulated one of the ends of a connecting rod (25, 25a) whose other end is articulated on a crank pin (26, 26a) secured to one of the shafts (27, 28) carrying one of the arms (5, 6) connecting a pair of pistons (3 and 3a, 4 and 4a). 3. Engine according to claim 1, characterized in that it comprises members ensuring the seal between the outer casing (1) and the rotary crown (2). 4. Engine according to claim 1, characterized in that the pistons (3, 3a, 4, 4a) are provided with members (18, 19) sealing with the fixed outer casing (1) and the crown (2 ) rotating interior. 5. Motor according to claim 1, characterized in that the diametral section of the annular space delimited by the casing (1) and the rotary crown (2) is rectangular. 6. Motor according to claim 1, characterized in that the diametrical section of the annular space delimited by the casing (1) and the rotary crown (2) is circular. 7. Motor according to claim 1, characterized in that the diametral section of the annular space delimited by the casing (1) and the rotary crown (2) is a combination of circular sectors and straight segments. 8. Motor according to claims 3 and 6, characterized in that the joint plane is located at the mean diameter of the torus. 9. Engine according to claim 1, characterized in that the outer casing (1) includes lights (14, 15) for the intake and exhaust of gases. 10. Engine according to claim 9, characterized in that the openings (14, 15) for the admission and the exhaust of the gases have the developed length corresponding to the maximum spacing of the pistons (3, 3a, 4, 4a) and the maximum width compatible with the fixed casing (1). 11. Engine according to claim 1, characterized in that the casing (1) comprises a housing for mounting a fuel injector (13) for an engine operating according to the Diesel cycle. 12. Engine according to claim 1, characterized in that the casing (1) comprises a housing for mounting a spark plug (13) for an engine operating according to the ignition cycle. 13. rotary internal combustion rotary engine according to claim 1, characterized in, that it comprises a fixed casing (1) in which are arranged, along the same axis and symmetrically, two modules offset by 90 ° each comprising four pistons ( 3, 4, 103, 104) diametrically connected in pairs by means of two arms (5, 6, 105, 106) and moving in an annular space delimited by the casing (1) and a rotating crown (29, 129) constituting the output drive shaft or being connected thereto, said rotary rings (29, 129) of the two modules being connected by means of transmission to the shafts (27, 28, 127, 128) which are integral with the arms (5 , 6, 105, 106) carrying the pistons. 14. Motor according to claim 13, characterized in that the transmission means comprises two pinions (22, 22a) common to the two modules which mesh with a ring gear (20) provided in the casing (1), each of the pinions (22 , 22a) being driven on one side by a crank pin (26, 126) secured to the external shaft (27, 127) connected to the arm (5, 105) of a pair of pistons (3, 103) of each module and on the other side by a crank pin (126a, 26a) secured to the internal shaft (128, 28) connected to the arm (106, 6) of the other pair of pistons (106, 6) of each module. 15. Motor according to claim 14, characterized in that the crank pins (26, 126a, 26a, 126) which are connected to the drive shaft (23, 123a, 23a, 123) of each of the pinions (22, 22a ) are angularly offset by 90 °.

Images