DE3127386A1 - Pneumatic drive unit for producing a reciprocating movement of a drive shaft - Google Patents

Abstract

A pneumatic drive unit for producing a reciprocating movement of a drive shaft, especially for the actuation of windscreen wipers in buses and heavy trucks, is characterised by a segment shaped, compression-resistant housing, which is divided into two chambers by a swivel piston fixed on a drive shaft. Each of the two chambers is connected by way of a ventilation and venting duct and a control duct to a valve unit. The control ducts are each closed by a spring-operated valve, which is opened by the swivel piston in that limit position in which the assigned chamber has the maximum volume. In addition the valve unit has a double acting piston capable of sliding to and fro in a housing, which piston can be locked in either limit position by a locking device. The control ducts each lead to chambers of the valve unit separated by the piston and when pressure is admitted lead to reversal of the piston into its other limit position in which the ventilation and venting duct of the chamber just then having the maximum volume is connected to the surroundings and the ventilation and venting duct of the other chamber, which just then has the minimum volume is connected to a compressed air source.

Description

The pneumatic drive unit represents a system that is primarily Line is intended for the operation of windshield wipers in buses and trucks, but can also be used elsewhere, where the transmission of a torque Necessary due to oscillatory movements in a segment of a circle at a certain angle is.

The system according to the invention provides a drive unit for the first time created that only with pneumatic components and with only one pneumatic Line from the compressed air source and works without any other energy sources.

There is no special cleaning or oiling of the air. Because of this System is also the programmed actuation of the drive of the windshield wipers in solved a certain end position.

With regard to conventional solutions of pneumatic drives with mechanical Reversing devices, this drive unit undoubtedly has the following advantages: 1. It enables application to windshield wiper drives with synchronous actuation two or more wipers, which is the case with motors with mechanical reversers is not possible due to insufficient force.

2. The pneumatic valve unit according to the drive unit according to the Invention is more reliable at all pressures compared to mechanical Reversing devices, which are often blocked at higher pressures, are on the other hand they are always in a working position, while mechanical reversers have at least one dead point in which the engine can be completely shut down can.

3. A programmed drive with mechanical reversers was up to now not possible to realize while the pneumatic drive unit solves the problem completely.

Found for the synchronous actuation of the windshield wiper drives Until now only electric motors have been used. The system with pneumatic Drive units is the electric motor because of its programmable actuation on an equal footing, but has undoubted advantages in comparison: 1. It relieves the burden the total electricity demand for buses and trucks, which is often at risk, and makes of the cheap compressed air use that is always in abundance in these vehicles is present and is normally vented into the atmosphere.

2. The pneumatic drive unit has approximately the same dimensions twice the strength.

In buses with a built-in electric motor with a torque of 30 Nm becomes a pneumatic drive unit with a torque of 65 without any problems Nm installed under a pressure of 6 bar.

3. While with electric motors a sensitivity to overloads exists, the pneumatic drive unit is insensitive in this regard.

4. The electric motors also require complicated installations which breakdowns, especially in difficult working conditions, can occur, in particular with regard to moisture and soiling, a common occurrence in operation Buses and trucks. When installing the pneumatic drive unit there are practically no places where more serious breakdowns can occur.

The object of the invention is to create a drive unit, which does not have the shortcomings of the known drives and, in contrast, those in the preceding has the advantages described.

This object is achieved by what is characterized in the claims Middle.

The working principle of the pneumatic motor unit is based on the Drawings explained in more detail below: FIGS. 1 and 2 represent two characteristic ones Represent working positions of the pneumatic drive unit according to the invention.

The pneumatic drive unit represents a functional unit of three interconnected components: - pneumatic drive motor, - pneumatic Valve unit and - pneumatic Han with seal.

The pneumatic drive consists of a housing with two symmetrical Halves that are hermetically sealed by screws 2 table connected and through Pins 9 are centered.

Swivel pistons with shaft 7 are mounted in the housing half 1 and divide the working chamber into two parts, working chamber a and working chamber "b".

The housing halves 1 are provided with channels c, d, m and n, the are in communication with corresponding channels of the pneumatic valve unit.

Channels c and n are opened and closed by moving them of the spring seal 3 and 8.

The pneumatic distribution unit consists of the following elements: Im Housing 12, the piston 6 is located on the right end of which there are two balls 14 with springs 15 are movable along the vertical axis.

The balls rest against a cam lock 16. The housing 12 is closed with lids 4 and 10. There are shock absorbers on the bottom of the lid 4 and 10 5 and 13.

Sealing of movable and non-movable elements takes place on one of the usual ways in pneumatics.

Except for the duct extensions in the valve unit for the ducts c, d, m and n, in the actuator housing there are still input valves in the valve unit and output ducts with silencers f and h. The input channel g is through a Plastic hose connected to the outlet channel p of a pneumatic valve.

The pneumatic valve consists of the following elements: In the valve body 17 is a slider 18 with a screw groove S. Slider 18 is through the Spring 21 leaning closely against seal 20. Elastic bolt 19 is used to limit the turning angle of the slider 18.

Lid 22 closes the tap from the lower side.

The seal is made in a manner customary in pneumatics.

By lever 11 slider 18 is rotated so that for the different Positions of the screw groove 5 in the valve are larger or smaller passages.

Depending on the position of the slider 18 and the static pressure In the input channel r and output channel p you get the desired values of the dynamic Pressure that is fed into the pneumatic pulse distributor.

The functioning of the pneumatic drive unit is described below explained with reference to FIGS. 1 and 2.

Fig. 1 - First characteristic working position The sealing tap air is under constant pressure and a certain flow rate through the inlet channel r supplied. In a certain position of the lever 11 is through the output channel Valve unit air under the desired dynamic pressure through the inlet channel g supplied.

In the position shown, the swivel piston 7 rises in a clockwise direction under pressure in the working chamber "a" moving the spring seal 3 and is channel c free. From the working chamber a via channel c, air comes under pressure into the chamber k of the distributor and exerts pressure on the piston 6.

Chamber e (Fig. 2) is through the exit channel at this moment f vented with a silencer so that no pressure from this side of the piston 6 is available.

Piston 6 pushes balls 14 by its own movement, connected by spring 15 and back through the cam lock 16. The force or pressure in the chamber k, necessary for reversing the piston 6 from the position in Figure 2 to the position according to Figure 1, is defined by the stiffness of the spring 15.

This is an essential feature because it enables a temporal one Programming of the number of vibrations of the pneumatic drive unit or the locking of the drive in an end position as long as the static pressure of the chamber k is not one Has reached the value for reversing the piston 6 into the second working position necessary is.

In practice, a frequency of less than 5 minutes with a Rest of 4 to 5 seconds reached in each end position. When the piston 6 is completely moved beyond the cam lock 16, he takes the position shown in picture 1. The resulting impact and sound is absorbed by a shock absorber 5 decreased. As soon as the piston 6 assumes the position shown in Fig. 1, the chamber k vented through the outlet channel h with silencer 4.

At the same time, the working chamber a is through channel d and exit channel f vented with a silencer and remains so as long as the piston of the valve unit remains in the position of image 1.

Air under pressure flows through inlet channel g and channel m and comes to the working chamber b. At the first moment the one in chamber b brakes Air pressure the movement of the piston 7 to a standstill, then he moves it in the opposite direction. As soon as the shovel crosses a certain small angle, the spring seal 3 is released and closes channel c. The pivot piston 7 moves continue under air pressure until it reaches the position shown in Fig. 2.

Fig. 2 - Second characteristic working position The piston 7 comes, moving under air pressure in the working chamber b into position according to Fig. 2 and by lifting the spring seal 8, the channel n is opened. The chamber k of the distributor is vented through the outlet channel h with a silencer, because the piston 6 is located is still in the position shown in Fig. 1.

Air under pressure flows from the working chamber through channel n into the Chamber e and moves piston 6 to the position shown in Fig. 2. The cam lock 16 is in the same role as in the first characteristic working position, and the shock absorber 13 absorbs the resulting shock and the sound.

In this position the working chamber b comes via channel m and the exit channel h with silencer for ventilation. At the same time, air flows through the inlet duct g and channel d under pressure into the working chamber "a", brakes the movement of the swivel piston 7 to a standstill and then pushes the piston 7 in the opposite direction. The working cycle then continues through the coming from the tap into the valve unit Air pressure defined speed.

Is essential. that the piston 6 of the valve unit is only one of the can occupy two jobs. or in ieder position of the piston 7 is only one of the channels d or m is connected to the inlet channel cr. Correspondingly the working becinn of the motor is absolutely feasible for all positions the standstill of the piston 7 when work is interrupted.

Working angle, different working pressures, torque and number of vibrations can be set in various ways, depending on the design solution, which is based on the same working principles as described here.

Practical drive units according to the invention with dimensions on a scale of 1: 1 according to Fig. 1 and 2, which are already parallel to the drive during operation working windshield wipers in buses have the following technical Data: - Working pressure 2.5 - 10 bar - Working angle 90 "- Torque at pressure of 6 bar 65 Nm - number of vibrations continuously variable 5 - 40 min

Claims (5)

Pneumatic drive unit for generating a reciprocating Movement of a drive shaft claims ½) Pneumatic drive unit for Generating a reciprocating movement of a drive shaft, in particular for operating windshield wipers in omnibuses or heavy-duty trucks, g e k e n n -z e i c h n e t through the features: a) a segment-shaped, pressure-resistant Housing (1), which is in two chambers is divided, b) each chamber (a, tf is via a ventilation channel) (d, m) and a control channel (c, n) with a valve unit connected, c) the control channels (c, n) are each closed with a spring valve (3.8), the is opened by the pivot piston (7) in that end position in which the associated Chamber (a, b) has the maximum volume, d) the valve unit has an in a housing reciprocating double-acting piston (6) through which a locking device can be locked in each end position, e) the control channels (c, n) each lead to chambers (e, k) of the valve unit which are separated by the piston (6) and cause the piston (6) to switch to its respective position when pressure is applied other end position in which the ventilation duct (d, m) of the chamber (a, b) with the straight maximum volume with the environment and the aeration or ventilation duct (d, m) of the other chamber (a, b), which accordingly has just minimal volume, is connected to a compressed air source. 2. Drive unit according to claim 1, characterized in that g e k e n n -z e i c h n e t, - that the latching device consists of two pressed apart by means of a spring (15) Balls (14) and a corresponding cam lock (16) consists. 3. Drive unit according to claim 1 or 2, characterized g e k e n n z e i c h n e t that shock absorbers at the two ends of the housing of the valve unit (5,13) are provided for the piston (6). 4. Drive unit according to one of claims 1 to 3, characterized g e k I n e n n e i n t, that in the out ducts (f, h) of the valve unit Silencers are provided. 5. Drive unit according to one of claims 1 to 4, characterized g e k It is noted that there is a pneumatic air source between the compressed air source and the valve unit Hahn is arranged, characterized by a tap body (17) with an air inlet and outlet channel (r, p) and one operable by means of a hand lever (11), with a keyway (f) provided sliding body, which has an air passage channel with variable Cross-section forms