DE1105730B - Control device for a hydraulic motor with reciprocating piston for driving aircraft windshield wipers - Google Patents

Description

Control device for a hydraulic motor with reciprocating Pistons for powering aircraft windshield wipers The invention relates to to a control device for a hydraulic motor with reciprocating Pistons for driving windshield wipers, in which the inlet and outlet of the Motor under the control of a reversing device provided with a snap-over mechanism stands.

Known control devices of the aforementioned type, which for controlling of hydraulic motors for driving windshield wipers in vehicles find and in which the reversing device is exclusively under the influence of springs are used to control hydraulic motors for driving Windshield wipers are not suitable on aircraft where the engines are operated by a work item to be operated, taken from the general hydraulic system of the aircraft and its pressures are therefore subject to strong fluctuations.

It must also be taken into account that with the ever increasing airspeeds the air pressure exerted on the windshield wipers and their drive types Loads have increased significantly, resulting in a corresponding increase in the Has made windshield wiper drive arms to be issued necessary torques.

The purpose of the invention is to provide a control device for hydraulic motors to drive the windshield wipers of aircraft to create which despite the strong Fluctuations in the working medium pressure and due to atmospheric influences Always a perfect drive due to the changing loads on the windshield wipers the windshield wiper ensures.

According to the invention, the aforementioned is in a control device Type in which the snap-over reversing device of an auxiliary control piston actuated by the working medium pressure is driven, a Device dependent on the working medium pressure is provided, which controls the movements of the Temporary inhibition of the auxiliary control piston is permitted.

In other words, this inhibiting device has the task of working of the auxiliary control piston for driving the reversing device for reversing the Working medium in the hydraulic motor as a function of the working medium pressure to stop temporarily until the equipment operating the engine has the required Pressure has reached, whereupon the inhibiting device becomes ineffective, so that the auxiliary control piston can operate the reversing device.

In one embodiment of the invention, the clamping device can have two freely movable pistons and guides that limit the movement of these pistons, which are in alignment with the auxiliary control piston and form working fluid chambers which allow the freely movable pistons to move with their piston rods to axial zones of the Apply the end faces of the auxiliary control piston in order to temporarily inhibit or stop its full stroke movement in both directions.

According to a further feature of the invention is one with the working medium source connected main control and metering valve is provided, which has separate outlets to the inhibiting device and to the reversing device provided with the snap-over mechanism possesses and which working medium when it is opened from the closed position the working medium source first to the inhibiting device and then to the reversing device leads.

The invention is illustrated below with reference to the drawing, for example explained in more detail: FIG. 1 is a schematic section through a windshield wiper drive system with hydraulic motors and a control device designed according to the invention for the engines, with the parts in one. End of work position reproduced are; Figure 2 is a similar section showing the parts in an intermediate position reproduces; Fig.3 is a similar section in which the parts are shown in the other end-of-work position; Fig.4 is an enlarged Cross-section held to scale along the line 4-4 of FIG. 5 through an embodiment the reversing device and the inhibiting device; Fig. 5 is a section according to Line 5-5 of Fig. 4. General Arrangement In Figs. 1 to 3, a is by hand operable main control valve or a valve unit 1 is provided which is controlled by a Line 2 aircraft system fluid is supplied and the two successively Has openable delivery lines 3 and 7 for the liquid. Line 3 leads when the valve 1 is initially open, system pressure fluid closes immediately a main actuation and equalizing piston mechanism 6 'with hydraulic fluid working actuation unit 6. The line 7 for the measurement liquid leads from valve 1 to a fluid reversal or fluid direction control Valve mechanism 6 ″ of the actuating unit 6. The valve mechanism 6 ″ leads to further opening the control valve 1 metered working fluid alternately through Lines 11 and 14 to motors 12 and 13 for the reciprocating windshield wipers. The motors mentioned are connected in parallel to the actuation unit 6.

A reciprocating main actuating or reversing piston 10 of the Mechanism 6 'actuates the valve mechanism 6 "for directional control by actuates a spring-loaded snap or knee joint mechanism 16, with which the piston 10 is mechanically connected in a suitable manner, as shown schematically in FIG. 1 is indicated by the dash-dotted line 20.

The knee joint mechanism 16, which is shown schematically in Fig. 1 and in more detail is shown in Fig. 4, is formed essentially as the mechanism according to U.S. Patent 2,451,449.

When the reversing piston 10 by pressure fluid in the actuation system is moved into one of its two outermost positions, which is illustrated in FIGS. 1 and 3, respectively causes or permits a valve operating rod 21 of the knee joint mechanism movement of pistons 8 and 9 of the directional control valve in either of the two positions shown relative to the associated parts, as can be seen from a comparison 1 and 3 can be seen.

In each of these positions the feeding of measured Pressure fluid through the line 7 and the line 11 or 14 the beginning of new Strokes on seldom the wiper motor pistons 17 and 18. The knee joint or Pressure switch spring 22 and associated parts as described in the U.S. Patent 2,451,449 are described hold the valve control rod 21 in the two shown Positions until recirculation takes place and the toggle mechanism a "hammer blow" effect with regard to the displacement of the valve piston 8 and 9 from one position to the other.

Compensating piston mechanism The reversing piston 10 of the actuator 6 (part 6'i is in a cylindrical bore 23 of the body B of the actuating unit between suitable limiting shoulders freely movable, and the opposite Ends of the bore 23 form chambers 26 and 27 which receive the wiper motor signal pressure. These chambers are z. B. through passages 26 'and 27' with the relatively inner Ends of additional bores 24 'and 25' that are in general alignment with the bore 23 are in free communication, and the bores 24 'and 25' have, as shown, same diameter, which is slightly smaller than the diameter the bore 23. The reciprocating compensating or balancing pistons 24 and 25 are subjected to the variable system supply pressure at their opposite ends from line 3 or a pressure proportional to this in the corresponding pressure chambers 28 and 29, which, as indicated at 3 ″, are connected to one another, exposed, The Compensating pistons 24 and 25 have appropriately guided rod parts 24 "or 255 "to the stop on associated end faces of the reversing piston 10. The axial, one another facing surfaces of the balancing pistons 24 and 25 (which are opposite the surfaces, continuously exposed to the system supply pressure) are alternated by reversing valve action the pressure in the chambers 26 and 27 and associated with the windshield wiper motor actuating Chamber spaces and exposed to negligible or outlet pressure.

The balance piston rods 24 "and 25" have relative to those shown Delimiting shoulders. which the movement of the balance piston against the reversing piston 10 stop, and with respect to the stop shoulders of the piston 10 such a length, that if z. B., as shown on the right in Fig. 1, the one balance piston (See piston 25) by supply system pressure inward to its stopped position is moved, he the reversing piston 10 in a partial stroke position (see. Fig. 2, piston 25) can stop and temporarily prevents the reversing piston 10 from making the necessary Execute movement to bring the knee joint mechanism 16 over the dead center position.

Directional control valve mechanism In the directional control valve system (Mechanism 6 ") is when the valve pistons 8 and 9 are in the one shown in Fig.1 Position are the line 7 for the measured liquid with the reversing valve chamber 26 and the chambers 12 'and 13' of the windshield wiper motors 12 and 13 are connected. In in this position the directional control valve pistons 8 and 9 become the motor chambers 12 "and 13" and the reversible piston chamber 27 with a liquid return passage 15 shown below the knee joint mechanism 16 for discharging fluid connected from the wiper motor chambers 12 "and 13". Indians with respect to each other reverse position of the directional control valve piston 8 and 9 (Fig.3) is measured Pressure fluid from the line 7 to the; Wiper motor chambers 12 "and 13" and admitted to the reversing piston chamber 27, and the correspondingly opposite one another Parts of the system are connected to the outlet or the liquid return passage 15 tied together.

Main control valve The main control and metering valve 1, as shown schematically in FIG. 1, has a body 30 with fittings (not shown) for the connection of aircraft system pressure fluid in the passage 2 '. The body 30 is similarly provided with a port 3 'for supplying system pressure fluid to the balance piston chambers 28 and 29, and with a port 7' for allowing metered fluid into the line 7. A floating plug 31 which is inserted in a bore 32 of the Body 30 is slidable, closes the main supply passage 2 'from communication with the passages 3' and 7 'when the manually operable, threaded spindle 33 is in its illustrated fully closed position. When the spindle 33 is rotated upward, the first operation is to allow fluid past the valve seat surfaces 31 'to the passage to charge the interconnected chambers 28 and 29 of the balance pistons 24 and 25; meanwhile, the incoming system supply pressure causes the float plug 31 to follow the spindle 33 and hold the lower end of the spindle in a tight fit 33 'with an axial bore 31 "of the float plug. causes the floating plug 31 to be stopped by a stop shoulder 32 'in the bore 32, whereupon a still further upward movement of the spindle (also shown in Fig. 2) the axial Du rchlaß 31 "to establish the connection with the passage 7' and the line 7 for the fluid for controlling the motor speed to the windshield wiper motors via the directional control valve mechanism 6 ". Operation The main actuating or reversing piston 10 of the mechanism 6 is, as already mentioned, from one extreme position (Fig. 1) to its other extreme position Position (Fig. 3) moved by measured pressure fluid in the lines 11, 11 'or the lines 14, 14' t, acting on the wiper motor pistons 17 and 18 as soon as the toggle mechanism 16 has caused a reversal of the working positions of the reversing valve pistons 8 and 9 relative to the associated valve passages, as z. B. a comparison of Figs. 1 and 3 shows. The full stroke movement of the piston 10 (ie such a movement which is sufficient to bring about a complete knee-joint action of the mechanism 16) is, however, temporarily due to the actuation of the compensating pistons 24 and 25 as a result of their respective rods 24 "and 25" resting on cooperating relatively opposite one another Limit stop surfaces of the piston 10 until both wiper motor pistons 17 and 18 have completed their full stroke movements or until both motor pistons otherwise, e.g. B. by ice accumulation on the windshield, are mechanically blocked against movement in the directions in which they have been moved. The restraint effect of one of the equalizing pistons 24 and 25 continues, e.g. B. until the measured pressure fluid, which acts on the motor pistons 17 and 18, has increased against the then prevailing maximum available supply system pressure or has almost reached it, which at any time during the windshield wiper motor activity to the two compensating pistons 24 and 25 in their associated chambers 28 and 29 is applied.

The restraint effect described above seldom affects the balance piston 24 and 25 can easily be seen from a comparison of FIGS. 1, 2 and 3, if assumed is that in Fig. 1, the directional control valves 8 and 9 are previously reversed that System pressure begins in the equalizing piston chamber 28 on the left side of the equalizing piston 24 to act, and that measured fluid pressure in the lines 11 and 11 'builds up (the opposite lines 14 and 14' and the pressure chamber 27 are now in the condition for the outlet) so that the movement of the wiper motor piston 17 and 18 and the reversing piston 10 to the right begins. The left balance piston 24 moves to the right to its stopped position (Fig. 2) and pushes the piston 10 before, and he piston 10 (Fig. 2) moves further to the right by action of measured liquid on his left side until moving through the rod 25 ″ of the compensating piston 25 is stopped. In this stop position of the piston 10, the knee joint mechanism 16 can be started depending on its design have to turn in the direction in which he is turning the direction reversing valves 8 and 9 are actuated in the reverse position (Fig. 3). However, the delivery system pressure is acting in the equalizing piston chamber 29, which is then higher than the pressure elsewhere in the system is, via the associated compensating piston 25, so that it occurs prevented by knee joint action beyond the dead center position.

As a function of the effective area of the piston 10 in the left chamber 26 (which is subjected to the measured pressure that actuates the windshield wiper motor) in relation to the effective area of the piston 25 (which is subject to the usually higher system pressure and to a certain extent counteracted by the knee-joint spring force further rightward movement of the piston 10 is increased) the further rightward movement of the piston 10! do not occur until the pressure acting on the left surface of the piston 10, e.g. B. has increased enough due to the stop of the engine pistons 17 and 18 to overcome the two opposing forces. The surface of the piston 25 in the chamber 2. 9 is preferably only sufficiently less than the area of the piston 10 in the chamber 26 so that a through buckling of the mechanism 16 occurs over the dead center position close to the point where the wiper motor working pressure the then prevailing Zufuhrsy stemdruck has balanced. From the foregoing it can be seen that upward changes in the supply system pressure from any presumed effective basis may have little or no effect on the circulatory or automatic reversal action, and that the system pressure may be exhausted and still perform properly provided it remains sufficient in order to actuate the windshield wiper motors and to overcome the toggle spring resistance in the relative position of the actuation parts, as shown in FIG.

Since the hydraulic circuit and actuation mechanism is bisymmetrical is about the vertical center line of the knee joint mechanism 16 (e.g., longitudinally, the dash-dotted line 20, Fig. 1), is the leftward lifting part of the complete Working cycle is of course the same as the one described above, and the and forward movement of the wiper motors 17 and 18 automatically becomes so continued for a long time, again measured pressure in the line 7, as it was for the windshield wiper speed control is set by the manually operated valve 1, sufficient to any Overcome lekken that is in the actuation unit or to the Wiscber engine piston can enter, or until the main control valve is actuated so that the axial passage 31 ″ in the floating plug 31 is closed. By slow Closing the main control valve can set the wipers at any desired Stopped at the end of their engine strokes. Windshield wiper synchronization If that Actuating system is arranged so that there are two or more windshield wiper motor units operated, as illustrated by the motors 12 and 13 connected in parallel the engine pistons may require synchronization at intervals. if the wiper motor units are free to operate more or less independently of each other to work, one of the wipers, e.g. B. in the middle of its stroke an obstacle, such as ice, is blocked, and when this occurs it is desirable to that the other windshield wiper motor or motors complete their stroke before a new one Circuit occurs, and that the blocked wiper is returned so quickly try to move again as possible. When the wiper blade W, which is connected to one of the motors 12 and 13 as shown schematically, is stopped by such an obstacle, the other wing will continue to move until it also encounters an obstacle or until it has reached the end of its full stroke achieved. In either case, the build-up of fluid pressure, as described, causes a cycle or a reversal of the stroke if no wing can advance further, and the windshield wiper that was previously stopped then goes to its initial position first back and wait there for the stroke to be completed by the other wiper. then both wipers start new strokes at the same time. That way, the two will Wiper, if not synchronized again at the end of each stroke that was completed at the same time.

FIGS. 4 and 5 the knee joint mechanism 16, as partially shown in FIG. 1 is illustrated in more detail in the right part of FIG. A circular one Drive plate or pulley 40 in body B is through a suitable shaft arrangement 41 connected to a gear 42, which with teeth 43 of the rack part you, reversing piston 10 combs. The plate 40 on the shaft assembly transmits through angularly spaced One or more pegs 40 'and 40 "of the plate limit the movement of the piston 10 on a knee bar or a handlebar 44, which can pivot independently and freely on the axis A (Fig. 4) of the shaft arrangement 41 is arranged. The handlebar 44 has one on him to steered cam 45, which I is eccentric to the axis A and optionally with relatively opposite stop surfaces 21 'and 21 "of the directional control valve actuating rod 21 comes into engagement. The knee joint spring 22 is with pins on the handlebar 44 and connected to the cam 45, as a comparison of FIGS. 1 and 4 clearly shows. The toggle mechanism has sufficient clearance between the cam 45 and the work bar surfaces 21 'and 21 "for a percussion effect on the valve control rod 21 during movement the valve piston 8 and 9 from each position shown in the relatively opposite Position.

In Figure 5, the bore 23 (see. Also Figure 1) in the body B, which contains the reversing piston 10, provided with sockets 46 and 47 in which the bores 24 'and 25' for the pressure compensation pistons 24 and 25 and the passages for the connection of the bores 24 'and 25' with the pressure chambers 26 and 27 are formed. Fig. 5 shows suitable leak-tight closures between the various elements, as they are preferably used. The meaning of the other parts included in 4 and 5 are shown, is readily apparent from the foregoing description.

Claims (3)

PATENT CLAIMS: 1. Control device for a hydraulic motor with reciprocating piston, in which the inlet and outlet of the engine under the control of a reversing device provided with a snap-over mechanism is in place, which is driven by an auxiliary control piston actuated by the working medium pressure, for the drive of aircraft windshield wipers, characterized by a working medium pressure dependent device (6 ') for temporarily inhibiting the movements of the auxiliary control piston (10). 2. Control device according to claim 1, characterized in that the inhibiting device (6 'two freely movable pistons (24, 25) and the movement of these pistons limiting Has guides (24 ', 25') which are in alignment with the auxiliary control piston (10) lie and working medium chambers (28, 29) form which the freely movable piston (24,25) allow their piston rods (24 ", 25") to reach axial zones of the end faces of the auxiliary control piston in order to achieve its full stroke movement in both Temporarily inhibiting or stopping directions. 3. Control device according to claim 1 or 2, characterized by a main control and Beinessun-Isventil (1) connected to the working medium source, which has separate outlets ( 3 ', 7') to the inhibiting device (6 ') and to the one with the L- mschnappmechanismus (16) verse surrounded Umstenereinrichtung (6 ") has, and which first results in its open from the closed position working fluid from the working fluid source to the Heninieinrichtung and then to the reversing device contemplated publications:.. German Patent No. 856266, 875179, 852093 ; French additional patent specification No. 2-1703 to patent specification No. 530 760.