EP0508838A1 - Reciprocating piston fluid-powered motor especially for windshield wiper - Google Patents

Abstract

The motor comprises a body (1) in which a rack (2) is slidably mounted; pressurised fluid means (P) for driving this rack in reciprocating translation; a pinion (3), mounted rotationally in the body and capable of interacting with the rack; an output shaft (4) of the motor rotationally driven by the pinion (3), and an inversion device (C) comprising a distributor (D) for altering the direction of action of the drive means (P) at each end of stroke of the rack. The pressurised fluid drive means (P) comprise two pistons (6a, 6b), respectively connected to each end (5a, 5b) of the rack (2) and capable each of moving in an associated cylinder (11a, 11b) situated on either side of the body (1), the pinion (3) being placed between the two pistons, the pressurised fluid being admitted alternately into one of the chambers (32a, 32b) of the cylinders opposite the rack. <IMAGE>

Description

The invention relates to a reciprocating fluid motor of the type which includes: a body in which a rack is slidably mounted; pressurized fluid means for driving in alternating translation of this rack; a pinion rotatably mounted in the body and adapted to cooperate with the rack; at least one output shaft of the motor driven in rotation by the pinion and a reversing device comprising a distributor for modifying the direction of action of the drive means at each end of travel of the rack.

The invention relates more particularly, but not exclusively, to a reciprocating pneumatic motor intended for driving a wiper arm, in particular for high speed trains.

It has been found that current pneumatic motors, for driving the wiper arms on vehicles traveling at high speed, in particular for high-speed trains, no longer provide sufficient training of the arms when the vehicles reach and exceed speeds of around 200 km / hour, in particular due to the effects of relative wind.

The invention, especially aims, to provide a reciprocating fluid motor, which develops a higher starting torque and power, under a given size, corresponding to that of current motors, in order to ensure a correct drive. the wiper arm when vehicles are traveling at high speed, in particular above 200 km / hour.

According to the invention, a fluid motor with reciprocating movement, of the kind defined above, is characterized in that the pressurized fluid drive means comprise two pistons linked respectively to each end of the rack, and adapted to move each in an associated cylinder located on either side 'Other of the body, the pinion being placed between the two pistons and the pressurized fluid being admitted alternately into one of the chambers of the cylinders opposite the rack.

Thus, the pressurized fluid acts on a surface of maximum cross section which makes it possible to obtain high performance, under a determined bulk.

Advantageously, the movement reversal device comprises, in each cylinder, a rod fixed, at one end, in the body and slidingly and sealingly passing through a bore of the corresponding piston, a longitudinal pipe and transverse holes being provided in this rod in such a way that, at the end of the active stroke of the corresponding piston, said pipe is placed in communication with the chamber in which the fluid under pressure is admitted, this pipe itself being in connection with conduits, provided in the body of the engine, suitable for admitting the pressurized fluid into a control circuit of a distributor which controls the supply and exhaustion of the cylinders, to cause the reversal of the movement.

The distributor comprises a sliding drawer and the distributor control circuit comprises, at each longitudinal end of the drawer, a chamber associated with one of said rods, chamber in which the pressurized fluid is admitted at the end of the rack's travel in the appropriate sense, to cause the drawer to slide and the movement to reverse.

Advantageously, the dispenser comprises an intermediate jacket in which the drawer slides, this jacket comprising, on its outer surface, annular grooves spaced axially, each groove having several passage orifices distributed over its bottom, the sum of the sections of the orifices provided being substantially equal to the section of the inlet or outlet orifice provided in the body of the distributor, but the diameter of each of the orifices of the groove being more reduced.

Said liner may consist of a stack of elementary rings, each ring having a groove, a seal being disposed between two adjacent rings. The seal is advantageously formed by a double O-ring comprising an outer O-ring part, the cross section of which has a relatively large diameter, and which is subjected to the tightening of the stack, and an O-ring part located radially inwards, whose cross section has a smaller diameter, and against which slide spans of the drawers, the inner toric part being connected, by a relatively flexible radial web, to the external toric part.

The distributor control circuit may include a fixed stop control device. This device can be constituted by a fixed stop cylinder disposed at the end of the distributor and in which a piston of section clearly greater than that of the drawer can slide, this piston comprising a pusher in abutment against the drawer, and being suitable for the subject to the action of the fluid under pressure, when the stopping of the engine is controlled, so that said piston pushes the slide into a determined position corresponding to the stopping of the arm wiper in a fixed position.

The rack may have a substantially semicircular section corresponding to a milled part of a rod of circular section whose cylindrical ends carry the above pistons, which are provided with a bore in their central part, crossed by the respective end of said rod. Advantageously, the "primitive" plane of the rack contains the axis of the rack so that the thrust of the pistons is perfectly centered.

Preferably, the rack slides in self-lubricating rings; the pinion is carried on each side by a bearing.

The cylinders, associated with each piston, are advantageously linked to the casing in a removable manner.

A damper device for the end of the piston stroke is advantageously provided on the bottom of the cylinder remote from the body of the engine; this damping device can be constituted by a finger, with frustoconical end, suitable for entering a blind housing from the end of the rack at the piston so as to create damping.

The invention consists, apart from the arrangements set out above, of a certain number of other arrangements which will be more explicitly discussed below in connection with a particular embodiment described with reference to the accompanying drawings, but which is in no way limiting.

Figure 1 of these drawings is an elevational view for the left part and a vertical section along the line I-I of Figure 2, for the right part, of a pneumatic motor according to the invention.

Figure 2 is an axial section along the line II-II of Figure 1, on a reduced scale.

Figure 3 is a half-section of the engine along line III-III of Figure 2 showing the rods of the reversing device and half of the pistons, the distributor being further shown in axial section, and on a different scale .

FIG. 4 is a top view of the motor in FIG. 1.

Figure 5, finally, is a section of an annular seal disposed between two elements of the jacket of the dispenser.

Referring to the drawings, in particular to Figures 1 and 2, one can see a pneumatic motor M, reciprocating, which comprises a body 1 in which is slidably mounted, parallel to the plane of Figure 1, and perpendicular to the plane of Figure 2, a rack 2 with which meshes a pinion 3 whose axis of rotation is orthogonal to the direction of movement of the rack. Pneumatic means P for driving in alternating translation of the rack 2 are provided. An output shaft 4 (see Figure 2) coaxial with the pinion 3 is rotated by the latter. An inversion device C comprising a distributor D is provided for modifying the direction of action of the pneumatic drive means P at each end of travel of the rack 2.

This rack, as shown in Figure 2, has a substantially semi-circular section corresponding to a milled central portion of a cylindrical rod, the ends 5a, 5b have a circular section. The teeth 2a of the rack are provided on the flat face of the semi-circular section and extend perpendicularly to the direction of movement of the rack.

Rack 2 slides in rings self-lubricating such as 7 placed in the bore of the body 1 intended to receive the rack.

The drive means P comprise two pistons 6 a , 6 b linked to each end 5 a , 5 b of the rack. These ends have a diameter smaller than that of the rod in which the rack has been cut so that a radial shoulder 8 is formed. Each piston includes a central bore 9 in which the respective end of the rack is engaged. The blocking in the axial direction of the piston against the shoulder 8 is ensured by an elastic split segment 10 anchored in a groove provided at the periphery of the corresponding end.

Each piston 6 a , 6 b is able to move in leaktight manner in an associated cylinder 11 a , 11 b . The piston 6 a , 6 b can be made of plastic.

The "primitive" plane of the rack 2 contains the axis of the rack so that the thrust of the pistons 6 a , 6 b is perfectly centered.

The cylinders 11 a , 11 b are arranged on either side of the body 1 and are constituted by simple cylindrical envelopes. As can be seen from FIG. 1, the axial longitudinal vertical plane Q is a plane of symmetry for the motor, so that the description will only be made for the right part of the motor shown in FIG. 1. The identical elements of the left-hand part will not be described and will simply be designated by the same reference numerals assigned with the letter b instead of the letter a used for the right-hand part.

The end of the cylindrical casing 11 a , located towards the body 1, is received in a bore 12 a and abuts axially against the transverse bottom of this bore. A seal 13 a is provided in an annular groove in the cylindrical wall of the bore 12 a so as to apply against the external surface of the casing 11 a .

At its other end, the casing 11 a is received in the bore 14a (also equipped with a seal) of a bottom 15 maintained on the body 1 by screws 16a through holes provided in ears 17a of the bottom 15 a, and screwed at the other other end in threaded holes 18 a of the body 1.

The cylinder 11 a is advantageously made of stainless steel. Its removable nature makes it easy to machine. It can be easily adapted to different strokes of the piston 6 a .

The bottom 15 a comprises, in its central part, towards the inside of the cylinder, a finger 19 a , with frustoconical end, mounted in an adjustable manner in the axial direction. The end 5 a of the rod has a blind hole 20 a provided, near its opening towards the outside, with an annular groove in which an O-ring 21 a is provided . At the end of the rack 2's race to the right in FIG. 1, the finger 19 a is able to enter the blind hole 20 a , so that the air is expelled from it and escapes through the space ring surrounding the finger 19 a , being braked. When the seal 21 has reached the cylindrical portion of larger diameter of the finger 19 a , a seal is established and an air mattress is trapped in the bottom of the blind hole 20 a . This dampens the end of the rack travel.

The pinion 3 is provided, on each side, with a cylindrical shoulder carried by a bearing 22, 23 mounted in the body 1.

The shaft 4 intended for driving the mechanism of the wiper arm, extends from the pinion 3, of which it is integral, passing through a relatively long cylindrical sleeve 24 serving as guide to this shaft 4.

Another coaxial shaft 25 extends from the pinion 3, on the side opposite to the shaft 4, and is provided, at its outer end, with a crank 26 wedged in rotation on this shaft, allowing, if desired , to block the engine, in the event that an emergency wiper device is started.

The movement reversing device C, shown in FIG. 3, comprises in each cylinder a rod 27 a , 27 b fixed by screwing a threaded end into a threaded hole in the body 1. The two rods 27 a , 27 b are preferably coaxial, parallel to the axis of the cylinders 11 a , 11 b and offset radially relative to this axis. The outer end of each rod 27 a , 27 b is received and held, in a sealed manner, in a bore 28 a , 28 b of the bottom 15 a , 15 b of the corresponding cylinder.

Each rod, such as 27 a , slidably and sealingly passes through a bore 29 a of the corresponding piston. A blind longitudinal duct 30a, opening at the end of the rod located in the body 1 is provided. A diametral transverse bore 31 a passes through the rod 27 a near its blind end. The location of this hole 31 a is determined such that in the end of the active stroke of the piston 6a, which corresponds to the position shown in Figure 3, the bore 31a opens into the chamber 32 and the pipe 30 a is placed in communication with the chamber 32 a , located on the side opposite to the rack 2, into which the fluid under pressure is admitted.

Another diametral transverse hole 33 a , the direction of which is preferably orthogonal to that of the hole 31 a , is provided in an area of reduced diameter of the rod 27 a so as to open out in a chamber 34 a of the body 1. A conduit 35 a , diagrammatically shown, is provided in the body 1 to establish a connection between this chamber 34 a and a control circuit F of the distributor D which controls the supply and the setting the exhaust of the cylinders 11 a , 11 b .

The bottom 15 a has a passage 36 which opens out, on the one hand into the chamber 32 a and, on the other hand, into a bore 37 a , with an axis parallel to that of the cylinder 11 a , and located radially to the outside of this cylinder. This bore 37 a receives, in a sealed manner, the end of a tube 38 a , the other end of which is received, also in a sealed manner, in a bore 39 a of the body 1. This bore 39 a is extended by a hole blind 40 a . A conduit 41 a , schematically shown, opens into the hole 40 a in the vicinity of its closed end. This conduit 41 has established a connection between the hole 40 a and an orifice 42 a of the distributor D.

The distributor D comprises a sliding drawer 43 comprising three grooves separated axially and delimited by larger diameter spans 44, 45, 46 and 47.

The drawer 43 is able to slide in an intermediate jacket 48 comprising on its outer surface five annular grooves 49 spaced axially.

Each groove 49 has several passage orifices 50, oriented radially, distributed over the bottom, the sum of the sections of the orifices 50 being substantially equal to the section of the supply orifice 51 or of the exhaust orifices 52, 53 provided in the body of the distributor D. The diameter of each orifice 50 is less than that of the orifices 51, 52, 53 which makes it possible to reduce the length of the distributor as much, because the axial stacking makes intervene five grooves 49 and therefore five times the diameter of an orifice 50.

The jacket 48 is advantageously constituted by a stack of five elementary rings 54, each ring having a groove, while a seal 55 is arranged between the faces of two adjacent rings. Each seal 55, as illustrated in FIG. 5, is advantageously formed by a double O-ring made of elastomeric material comprising an outer O-ring part 56 whose section has a relatively large diameter and which is subjected to the tightening of the stack of rings 54, and an O-ring portion 57 located radially inwards, the section of which has a smaller diameter. The bearing surfaces 44-47 slide against the internal radial surface of the section 57. This part 55 is connected by a radial web 58, of reduced thickness and relatively flexible to the external toric part 56. This flexibility facilitates sliding and reduces the risk of damage to the seal.

The drive circuit F includes, at each longitudinal end of the slide 43 a respective chamber 59, 59 b associated with the corresponding rod 27, 27b. The pipe 35 a , 35 b provides the connection between the associated chamber 59 a , 59 b and the chamber 34 a , 34 b .

Each chamber 59 a , 59 b is delimited by the transverse face of the end bearing surfaces 44, 47 of the drawer which slide in leaktight manner (thanks to a seal) in sleeves 60, 61 provided at each end of the stack constituting the shirt 48.

The axial ends of these sleeves 60, 61 are in abutment against covers 62, 63 closing the dispenser. An annular passage is provided all around the sleeves 60, 61 which have, at their ends, radial passages such as 64 allowing the annular passage in which the pipe 35 a or 35 b opens, to communicate with the respective chamber, 59 a , 59 b .

The control circuit F further comprises a fixed stop control device 65 disposed at the end of the distributor D, on the left according to the representation in FIG. 3. This device comprises a cylinder 66 fixed coaxially to the drawer D, on the cover 62. This cover has, in its central part, an opening with a sleeve 67. The bottom of the cylinder 66 has an orifice 68 intended to be connected to a pipe, not shown, which can be placed in communication either with an inlet pressurized fluid, either with the exhaust, usually the atmosphere. A piston 69, of section clearly greater than that of the drawer 43, for example double that of the drawer, is provided for sliding in leaktight manner in the cylinder 66. This piston 69 is provided, on the side of the drawer, with a pusher 70 sliding in leaktight manner in the sleeve 67 and capable of coming to bear, by an end of smaller diameter, against the transverse face of the bearing surface 44 of the drawer 43.

A compression spring 71 is provided between the piston 69 and the cover 62. The plunger 70 and the sleeve 67 are engaged in the turns of this spring 71, which is intended to possibly overcome an effect of adhesion or "sticking" of the seals provided on the plunger and the piston, on the surfaces cooperating with these seals.

However, the operation of the reciprocating pneumatic motor is as follows.

When the engine is stopped, it is in the position shown in FIG. 3, while the distributor spool 43 occupies the position corresponding to the lower half-cut of this same figure 3. The orifice 68 is supplied with pressurized fluid.

In this stop position of the engine, the chamber 32 is fed with fluid under pressure. The air pressure keeps the piston 6 a , and therefore the drive shaft, in the end of cycle position. The bore 31 a is uncovered and the pressurized fluid feeds the chamber 59 a , passing through the channel 30 a and the conduit 35 a . The drawer 43 is prevented from moving, under the action of the pressure prevailing in the chamber 59 a , due to the pressure exerted on the piston 69, of larger diameter, by the pressurized air admitted through the orifice 68.

The engine therefore remains stationary.

The engine is started by venting the orifice 68.

The piston 69 and its pusher 70 move to the left of FIG. 3, under the action of the spring 71, and no longer exert, on the slide 43, a thrust antagonistic to that exerted by the compressed air contained in the room 59 a .

The drawer 43 moves from the right to the left of Figure 3 to pass to the position shown in the upper half-section.

The orifice 51 then supplies the orifice 42 b which, via the conduit 41 b of the blind hole 40 b and the tube 38 b , supplies the chamber 32 b . The engine starts with displacement of the piston 6 b from the left to the right according to the representation of FIG. 3. This displacement meets no resistance on the part of the other piston 6 a because the chamber 32 a is connected to the atmosphere by the conduit 41 a and the orifice 52.

When the piston-rack assembly comes to the end of the stroke, due to the action of pressure on the piston 6 b , this piston discovers the passage 31 b which supplies the pilot chamber 59 b via the channel 30 b , the bore 33 b , the chamber 34 b and the pipe 35 b .

The drawer 43 then moves to take the position shown in the lower half-part of FIG. 3 so as to supply the chamber 32 a and bring the chamber 32 b to the atmosphere.

There is then a reversal of the movement and the piston 6 a moves from the right to the left of FIG. 3 by driving the rack 2 and the other piston 6 b . The back and forth movements of the rack 2 continue until the user controls the stopping of the engine by supplying pressurized air to the orifice 68.

The pressure acting on the piston 69 causes the blocking of the slide 43 in the position shown in the lower half of FIG. 3, with maintenance of the supply of the chamber 32 a with pressurized fluid.

Although the pressurized air reaches, through the passage 31 a , in the chamber 59 a , the reversal of the movement cannot be done since the drawer 43 is blocked.

The fixed stop position of the engine is therefore obtained in a determined position.

The reversal of this stop position can be obtained by reversing the mounting of the cover 63 and of the control device 65 comprising the parts 62, 66, 69 and 70.

Thus, each time that the stopping of the motor is ordered, the wiper arm will stop in a determined position, always the same.

It should be noted that a rolling can be provided on the exhaust of the cylinders 11 a , 11 b to adjust the speed of the rack.

The design of the fluid motor of the invention makes it possible, under a small footprint, to increase the power of the engine. At the level of the reversing device and of the distribution, there are practically no moving parts.

Claims (10)

Reciprocating fluid motor, comprising: a body (1) in which a rack (2) is slidably mounted; pressurized fluid means (P) for driving in alternating translation of this rack; a pinion (3) rotatably mounted in the body and adapted to cooperate with the rack; an output shaft (4) of the motor driven in rotation by the pinion (3) and a reversing device (C) comprising a distributor (D) to modify the direction of action of the drive means (P) at each end of stroke of the rack, motor in which the pressurized fluid drive means (P) comprise two pistons (6 a , 6 b ) linked respectively to each end (5 a , 5 b ) of the rack (2) , and able to move each in an associated cylinder (11 a , 11 b ) located on either side of the body (1), the pinion (3) being placed between the two pistons, the fluid under pressure being admitted alternately in one of the chambers (32 a , 32 b ) of the cylinders opposite the rack, characterized in that the movement reversing device (C) comprises, in each cylinder (11 a , 11 b ), a rod (27 a , 27 b ) fixed at one end in the body (1) and slidingly and sealingly passes through a bore ( 29 a , 29 b ) of the corresponding piston (6 a , 6 b ), a longitudinal pipe (30 a , 30 b ) and transverse bores (31 a , 31 b ) being provided in this rod so that active limit switch of the corresponding piston, said pipe (30 a , 30 b ) being placed in communication with the chamber (32 a , 32 b ) into which the fluid under pressure is admitted, this pipe (30 a , 30 b ) being in connection with conduits (35 a , 35 b ), provided in the body (1) of the engine, suitable for admitting the pressurized fluid into a control circuit (F) of a distributor (D) which controls the supply and exhausting the cylinders, to cause the reversal of the movement. Motor according to claim 1, characterized in that each rod (27 a , 27 b ) of the reversing device (C) is fixed by screwing a threaded end into a threaded hole in the body (1). Engine according to claim 1 or 2, characterized in that the cylinder (11 a , 11 b ), associated with each piston (6 a , 6 b ) is detachably connected to the body (1). Motor according to one of the preceding claims, characterized in that the distributor (D) comprises a sliding drawer (43) and that the control circuit (F) of the distributor comprises, at each longitudinal end of the drawer, a chamber (59 a , 59 b ) associated with one of said rods (27 a , 27 b ), chamber in which the pressurized fluid is admitted at the end of the rack (2) in the appropriate direction, to cause the slide to slide (43) and the inversion of the movement. Motor according to one of the preceding claims, characterized in that the distributor (D) comprises an intermediate jacket (48) with annular grooves (49), in which the drawer (43) moves, each groove (49) comprising several passage orifices (50) distributed over its bottom, the sum of the sections of the orifices (50) provided being substantially equal to the section of the inlet (51) or outlet (52) orifice provided in the body of the dispenser. Motor according to claim 5, characterized in that the jacket (48) is constituted by a stack of elementary rings (54), each ring comprising a groove (49), a seal (55) being disposed between two adjacent rings. Motor according to Claim 6, characterized in that the seal (55) is formed by a double O-ring comprising an outer O-ring part (56), the cross section of which has a relatively large diameter, and an O-ring part (57) located radially. inwards, the cross section of which has a smaller diameter, the internal toric part (57) being connected, by a relatively flexible radial web (58), to the external toric part. Motor according to claim 4, characterized in that the control circuit (F) of the distributor comprises a device (65) for fixed stop control, constituted by a cylinder (66) of fixed stop arranged at the end of the distributor ( D) and in which slides a piston (69) of cross section clearly greater than that of the drawer (43), this piston (69) comprising a pusher (70) bearing against the drawer (43) and being suitable for being subjected to the action of the fluid under pressure, when the stopping of the motor is controlled, so that said piston (69) pushes the slide (43) into a determined position corresponding to the stopping of the wiper arm in a fixed position. Motor according to one of the preceding claims, characterized in that the rack (2) has a substantially semi-circular section corresponding to a milled part of a rod of circular section whose cylindrical ends (5 a , 5 b ) bear the aforesaid pistons (6 a , 6 b ), which are provided with a bore (9) in their central part, crossed by the respective end of the rod. Engine according to one of the preceding claims, characterized in that a device for damping the end of the piston stroke (6 a , 6 b ) is provided on the bottom (15 a , 15 b ) of the cylinder remote from the body ( 1) of the engine, this damping device being constituted by a finger (19 a ), with frustoconical end, suitable for entering a blind housing (20 a ) from the end of the rack at the piston, so as to create a amortization.

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