US2348424A - Change-speed mechanism - Google Patents

Description

May 9, 19.44.` l l 1 T J. sHQRTER 2,343,424 Y CHANGE-SPEED MECHANISM Filed Feb. 12, 1941 s sheets-sheet 2 Patented May 9, 1944 CHANGE-SPEED MECHANISM Leo Joseph Shorter, Coventry, England, assignor to Singer Motors United, Coventry, England Application February l11e, 1941, serial No. 318,641 rn Great Britain Maren 15, 1940 lalms. (Cl. 74-328) This invention relates to change-speed mechanism, particularly for use in the drive of an automobile. y

There is a known form of three-speed gearbox of the layshaft type in which third speed (direct drive) and second speed are introduced by means of some form of synchronizing device and rst speed by means of a gear which is slidable, on the driven shaft of the gear-box, into mesh with a pinion fast on the layshaft, the latter preferably being a tubular one in `constant mesh through a gear pair with the driving shaft of the gear-box. It is an object of the present invention to provide improvements in this form of three-speed gear-box which will make for greater silence as regards first speed and by means of which the overall length of the gearbox can be reduced.

Furthermore, it is known to` associate with a layshaft type of gear-box an auxiliary changespeed mechanism (for example, one adapted to give an overdrive) which is preferably of the planetary type and is usually disposed at the tail-end of the gear-box. It is a further object of the invention to provide an improved form of gear-box casing which kcan be used either for such a gear-box alone or when the latter is to be used in combination with an auxiliary change-v speed mechanism; and, in particular, to ensure that the gear-box casing in either 'event will provide a satisfactory support for the end of the layshaft remote from the driving end and also for the driven shaft of the gear-box.

It is also known to operate such auxiliary change-speed mechanism by hydraulic means including a pressure-generating pump (which is preferably driven from the appropriate part of the gear-box), a hydraulic accumulator and a hydraulic mechanism (includingone or more cylinders and pistons) which can be connected to actuate the auxiliary mechanism, the admission of fluid-pressure to the hydraulic mechanism being controlled by a valve means. 'It is a further object of the present invention to provide improved means for disposing the pressure-generating pump, the hydraulic accumulator and the hydraulic mechanism, and, in particular, to arrange those parts as a unit, incorporating also the necessary valve means, which is adapted to be secured against one face of the gear-box casing, preferably against the underface thereof.

For a better understanding of the objects and advantages of the invention attention should be directed to the following description in which reference is made to the accompanying drawings. wherein:

Figure l is a sectional elevation of a threespeed gear-box tted withan auxiliary changespeed mechanism which is hydraulically controlled, the section being mainly on the lines I-I of Figures 2, 3, 4 and 6;

Figure 2 is a sectional plan through the layshaft;

Figure 3 is mainly a plan, taken on the line III-III of Figure 1. of the hydraulic unit of the invention:

Figures 4, 5 and 6 are cross-sectional elevational views taken mainly on the lines IV-IV, V-V and VI-VI, respectively, of Figure 1 and Figure 3: and

Figure 7 is mainly an end elevation, at two different sections, taken from the right of Figure 1.

The drawings show a driving shaft Il in constant mesh, through a gear pair I2, with a tubular layshaft I3 which is journalled on a stationary shaft I4 secured at its ends in walls ia, lib which are integral with the gear-box casing. I6 represents a double-acting synchronizing clutch of known form which is slidable on the driven shaft I1 and is shown in the neutral position. When moved to the left (Figure l) the direct drive is obtained, and when moved to the right the gear Il, in permanent mesh with the gear I9 fast on the layshaft, is locked to the driven shaft to give second speed. First speed is obtained by moving the gear 20, which is slidably splined on the driven shaft, into mesh with the pinion 2| on the layshaft. lThis pinion, it will be observed, is right at the rear end of the layshaft in juxta-position to the adjacent intermediate wall [5b of the gear-box casing, and is thus very firmly supported. To allow of using a normal form of gear-shift lever position the gear 2l is operated through a swinging striker fork 22.

Reverse drive is obtained by sliding the idlc gear 23 (shown in full lines in Figure 2 in its inoperative position) flrst into mesh with the pinion 2| and then into mesh with the gear 20, as shown by the chain lines 23a in Figure 2. Its movement may be effected by means of a slidable striker fork rod 24 and a swinging lever indicated at 25, this being shown in Figure 1 in the position it occupies when reverse gear is engaged. l

The gear-box casing is extended away from the driving end beyond the intermediate wall I5b. and it has an integral end wall ISc. If the gearbox is to be usedwithout an auxiliary changespeed mechanism the end wall I5c will form an additional support for the driven shaft I1. The gear-box is, however, shown as iitted with an auxiliary change-speed mechanism of a kind known per se. The casing 21 for the latter is secured to the end wall I5c round an opening in the latter. 'Ihe auxiliary mechanism includes a driven internally-toothed annulus 28 which is Journalled in the casing 21 and connected withv the planet-carrier 28 through a one-way clutch or free-wheel including rollers 38. The planetcarrier is fast on thedriven shaft I1 of the gearbox, and the planet pinions 3I intermesh the annulus 28 and the sun gear 32, which latter is the reaction element. Slidingly splined on the hub of the sun gear is a thrust bearing 33 operable by a rocking lever 34 and carrying a clutch plate 35, the lever being journalled on a cross-pin 36. The clutch plate is a dish-shaped pressing with a frustum-shaped end carrying internal and external fabric linings to coact with surfaces on the annulus 28 and the stationary casing of the gear-box, respectively. When the clutch plate is in the right-hand position shown, the sun geai' is locked to the annulus, to give a direct drive. When in the left-hand position the sun gear is held against rotation, to give an overdrive. i

The swinging lever 34 is actuated by hydraulic operating means under the control of the gearshift lever 31. This latter, it will be observed, is disposed on that side of the intermediate wall I5b which is remote from the driving end of the gear-box. The hydraulic operating means includes a hydraulic accumulator consisting of a cylinder 38 with a spring-pressed plunger 39 in its interior, a hydraulic cylinder 48 having a piston 4I therein, the latter being fast with a piston rod which is pivotally connected to the swinging lever 34, an oil pump 42, of a kind known per se, for supplying pressure to the accumulator, and various oil passages and valves. The accumulator and hydraulic cylinder are formed integrally with one another as a die casting, and adapted to be bolted against the underface of the gear-box at the points 44, 44, being thereafter enclosed by a detachable cover which is omitted in the views of Figures 4 and 6. A bracket 46 which is integrally formed with the accumulator casing has a bore 41 therein to receive the casing of the pump.

The layshaft I3 is offset slightly to one side of the vertical plane through the driving and driven shafts, as shown in Figure 4, and the accumulator is arranged with its axis in this plane and with the pump to one side, the plunger 48 thereof being in engagement with and driven by the eccentric 49 fast on the layshaft.

The pump, which picks up oil from the gearbox through a filter 50, can deliver the oil along a passage 5| to a passage 52 leading tangentially to the upper part of the operative end of the accumulator casingsee Figure 5. Communicating with the lower part thereof are oppositelydisposed passages 53 leading to passages 54 extending longitudinally of the hydraulic cylinder 48 on opposite sides thereof, up to ball control valves 55 provided' with hollow actuating members 56a, 56h which extend up into the bottom of the gear-box casing. When these are depressed, oil under pressure from the associated passage travels upwardly and along-longitudinal passages 51a, 51h, the ilrst of which leads to the left-hand end (Figure 1) of the hydraulic cylinder 48 and the other to the right-hand end.

The actuating members 56a, 56h can be selectively operated by means of pivotally-mounted arms 58 which are pressed upwardly by springs 59 and are engaged by slidable rods 6I extend ing through the gear-box casing and provided with inclined faces 62a, 62h at their upper endssee Figure '7. These inclined faces are on opposite sides of a block 63 provided with coacting inclined faces on its underside and biased by springs 64 to a central position. The gear-shift lever extends through the block so as to actuate it laterally of the gear-box when the gear-shift lever is so moved, the block having a longitudinal slot 65 along which the gear-shift lever can travel when moved in a fore-and-aft direction. The block is slidingly supported upon stationary bars 68 so as to partake only of transverse movement. Spring-pressed balls 61 coacting with notches in the block are provided for locating purposes in a known manner, as are also three sets of spring-pressed balls 68 for the different selector bars. Of these latter, 69 is that for second and third speeds, 18 that for first speed and 12 that for the reverse gear drive.

Referring now to Figure 7, the gear-shift lever is shown engaged with 81e first speed selector bar 18. Movement of the gear-shift lever into engagement with the selector bar 69 for second and third speeds will shift the block 63 to the left (Figure 7) without the block engaging the end 62a of the adjacent sliding rod 6 I. A further movement of the gear-shift lever in the same direction, when the selector bar has been moved to engage third speed, the direct drive, will cause the block to engage the end 62a of the adjacent sliding rod 6I and thus depress the actuating member 56a. This allows of the supply of fluid under pressure from the hydraulic accumulator along the passage 51a to the left-hand end (Figure 1) of the hydraulic cylinder 40, thereby driving the piston to the right and sliding the clutch disc 35 to the left against the pressure of springs 13, the thrust ring 33 being meanwhile guided by the pins 14. As previously mentioned, in these conditions the sun gear 32 is locked to the stationary casing, and an overdrive is obtained. When the gear-shift lever is returned to engage the selector bar 68 for third and second speeds, the actuating member 56a is released, the oil pressure applied to the lefthand end (Figure 1) of the hydraulic cylinder 48 is allowed to exhaust, and the springs 13 return the clutch disc to the position shown in Figure 1, to provide the ordinary direct drive.

Referring once more to Figure 7, when the gear-shift lever is moved into engagement with the selector bar 12 for the reverse drive, the block 63 is shifted to the right to depress the right-hand sliding rod 6I, thereby eiecting depression of the actuating member 56h and allowing the introduction of hydraulic pressure to the right-hand end (Figure 1) of the hydraulic cylinder 40. This hydraulic pressure, acting on the piston, assists the springs 13 in maintaining the clutch disc in the direct drive position shown in Figure 1, thereby to enable the clutch to carry the high torque encountered with the reverse drive. (It may here be mentioned that the principle of reinforcing the springs in this way for a high-torque gear position is known per se.) What I claim as my invention and desire to secure by Letters Patent of the United States 1. A change-speed gear-box incorporating an auxiliary hydraulically-operable, change-speed mechanism adapted to give an overdrive, said auxiliary change-speed mechanism having a control element movable to the overdrive position by the hydraulic mechanism and movable .to the direct-drive position, on the release of the hydraulic pressure, by spring bias, and said control element being additionally held in. the direct-drive position by the hydraulic mechansm when a high-torque speed of the gear-box is engaged, characterized hereby, that the admission of pressure to the hydraulic mechanism is effected by means of a double-acting wedgeshaped block, said block being movable by the gear-shift lever of the gear-box and being adapted to coact in its extreme positions with slidable rods through which` the appropriate valves of the hydraulic mechanism can be actuated.

2. The combination with a change-speed gear-box, of an auxiliary change-speed mechanism, hydraulic means for actuating said auxiliary mechanism, said hydraulic means formed as a unit including a pump, an accumulator, a hydraulic mechanism and valve means, said unit adapted to be bolted to one face of the `gear-box casing, operating rods for said valve means extending through said gear-box casing, a gearshift lever for said gear-box, and a block operable by lateral movement of said lever, said block coacting with said operating rods in certain positions of said lever to actuate said auxiliary mechanism.

3. In a change-speed gear-box incorporating an auxiliary change-speed mechanism which is operable hydraulically, a unit comprising a pressure-generating pump, a hydraulic accumulator, a hydraulic mechanism, adapted to actuate the auxiliary change speed mechanism, valve means controlling the admission of fluid pressure to the hydraulic mechanism, said unit adapted to be secured against one face of the gear-box casin operating means for said valve means, gear shiftingv means for said gear box, and means coacting with said operating means to actuate said auxiliary mechanism.

4. In a change-speed gear-box incorporating a hydraulically-operable, auxiliary, changespeed speed mechanism, a unit according to claim 3 in which the casing of the accumulator and the casing of the hydraulic mechanism are integrally formed and adapted to be bolted to the underface of the gear box casing, operating means for said valve means, a gear shift lever for said gear box, and a block coacting with said operating means in certain positions of said lever to actuate said auxiliary mechanism.

5. A change-speed gear-box incorporating a hydraulically-operable, auxiliary, change speed mechanism provided with a unit according to claim 3 secured against the underface of gearbox, the gear-box being of the layshaft type with the layshaft offset to one side o f the vertical plane through the axis of the driving and driven shafts located above the layshaft, the accumulator being arranged with its axis near the said vertical plane, the pump driven from the layshaft, arranged to one side of the accumulator, operating means for said valve means, a gear shift lever forsaid gear-box, and a block coacting with said operating means in certain positions of said lever to actuate said auxiliary mechanism.

LEO J. SHORTER.

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