GB1586311A - Air operated vehicle windscreen washers - Google Patents

Description

(54) AIR OPERATED VEHICLE WINDSCREEN WASHERS (71) We, TRICO-FOLBERTH LIMITED, a British Company, of Great West Road, Brentford, Middlesex, TW8 9HP, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to windscreen washers for vehicles in which the windscreen wipers are driven by a compressed air motor.

Its object is to provide a novel and very simple washer for such installations, which moreover can (if desired) provide water through one or another of two pipes according to the direction of motion of the windscreen wipers. This latter feature is desirable in washer installations where the water is conveyed to jets located on the wipers, because it is advantageous to have the water sprayed ahead of the wiper blade in each direction of motion.

A windscreen washer and wiper system according to the present invention includes a compressed-air-operated wiper motor comprising valve gear and a first piston member (as herein defined) arranged to move to the fro between two chambers and thereby provide drive for a wiper; a pump comprising a second piston member and a third piston member coupled to move to and fro in unison between respective further chambers; conduits connecting the chambers at the two sides of the second piston member to receive respectively the air pressures from two places in the motor or in a further valve controlled by the motor, being places chosen so that the differential between the pressures varies cyclically in each cycle of operation of the motor; and further conduits for supply and discharge of washer liquid to and from the chambers at the two sides of the third piston member, and valves to ensure flow of liquid from supply to discharge when the third piston member moves to and fro.

Definition of "piston member'' is contained in the final paragraph of this specification.

The two places may, for example, be the two chambers on each side of the first piston member; or they may be two conduits leading from a pilot valve to a main valve (as explained below with reference to Figure 5).

The accompanying drawings show examples of systems which embody the present invention. In these drawings: Figure 1 is a circuit diagram of a first system; Figures 2 to 4 are fragmentary diagrams of a second, third and fourth system; and Figures 5, 6 and 7 are circuit diagrams of a fifth, sixth and seventh system.

In Figure 1, the wiper motor is shown schematically as an air cylinder 10 containing a piston 10a which divides the interior of the cylinder into two chambers 11 and 12. It could equally be a semi-rotary vane motor, or any other equivalent reciprocating device.

Some form of automatic valve gear (not shown) switches the chambers 1.1, 12 alternately to pressure and exhaust, causing the piston 10a to reciprocate. Lines 13, 14 are connected to these two chambers.

The washer pump consists of a stepped piston having a central portion 15 of large diameter, extended by two portions 16, 17 of smaller diameter, sliding in corresponding bores in the washer body, against which they are sealed by seals 18, 19 and 20. These portions of the piston define air chambers 21, 22 and water chambers 23, 24.

The chamber 21 is connected to the line 13. The chamber 22 is connected to the line 14 via a valve 25, which may be operated manually, or by a suitably derived air pressure signal or by a solenoid, to bring the washer into action.

In the "off" configuration as drawn, the valve 25 connects the chamber 22 to atmosphere. Pressure in the line 13 will then move the pump piston to right, where it will stay, and the pump is inoperative.

When the valve 25 is moved to the left, to the "on" configuration, the chamber 22 is connected by the line 14 to the chamber 12 of the wiper motor. In consequence, when pressure is admitted by the wiper motor valve gear to the chamber 12, that pressure passes also via the line 14 to the chamber 22, while when pressure is admitted to the chamber 11, that pressure passes also via the line 13 to the chamber 21. The pump piston will then move to the left when the wiper motor piston moves to the left, and to the right when the wiper motor piston moves to the right.

As the pump piston moves, water is drawn from a reservoir 35 alternately to the chamber 23 through a non-return valve 26 or to the chamber 24 through a non-return valve 27, and simultaneously water is discharged from the chamber 24 through a non-return valve 28 to a line 29, or from the chamber 23 through a non-return valve 30 to a line 31. The lines 29 and 31 may lead respectively to jets mounted on the wiper blades on one side and the other, thus ensuring that water is sprayed ahead of the blades in both directions of the motion of the blades. Alternatively, the lines 29 and 31 may be joined together and deliver water to a fixed jet or jets.

Figure 2 shows an alternative form of pump. The pneumatic portion of the system is identical to that of Figure 1, and has not been drawn. In Figure 2 the large portion 15 of the pump piston carries a pair of seals 32, 33 spaced a suitable distance apart. Water is drawn from the reservoir 35 through a port 34 in the large diameter bore of the washer body. With the piston near the left of its stroke, the port 34 communicates with the chamber 24 allowing water to be drawn into that chamber from the reservoir 35. The port 34 is closed again after the piston has moved a small distance to the right, allowing water to be delivered to the line 29 via the nonreturn valve 28. The same happens, mutatis mutandis, for movement of the piston in the opposite direction. The port 34 and seals 32, 33 replace the non-return valves 26, 27 of Figure 1.

In practice, the air pressure available on vehicles is about 80 to 90 lbs/sq. in., but the differential pressure between the two sides of the piston 10a may be as low as 20 Ibs/sq.

in. If the system is to supply water to jets mounted on a wiper blade, the ratio between the areas of the portions of the stepped piston is conveniently such as to produce water pressure of about 5 Ibs/sq. in. If the system is to be used to supply water to a fixed jet or jets, the water pressure is conveniently about 20 Ibs./sq. in.

The arrangements shown in the Figures, using a stepped piston, are preferred, but it is alternatively possible to have two pistons, joined together by a piston rod, and these may either be connected so that one piston has air on each side, and the other has water on each side, or so that each piston has air on one side and water on the other.

In the third system, shown in Figure 3, the lines 13 and 14 are both permanently connected to the washer pump, and the valve 25 of Figure 1 is replaced by a piston 40 biased by a spring 41, and with a sealed ex tension 42 penetrating into the left-hand air chamber of the washer pump, to hold the washer pump piston over to the right in the unoperated position. To bring the washer pump into action, pressure is applied to the right-hand side of the piston 40 from a line 43 connected to a suitable control valve, and the piston 40 then moves to the left, freeing the washer pump piston and allowing it to reciprocate.

In all the systems described so far, the air pressure differential acting on the washer pump piston is the air pressure differential between the two chambers 11, 12 of the motor 10 (see Figure 1), which is whatever figure is required to operate the wipers. This can be as low as say 10 lbs/sq. in., the difference between that figure and the system pressure (which is typically 80 Ibs/sq. in. or higher) being absorbed by restrictors embodied in the motor, losses in the air lines, valve gear etc. The fact that this pressure differential between the chambers 11, 12 can be so low, and also that it can vary widely depending on operating conditions (it is much higher when the wipers are working on a drying screen) can be a disadvantage.

Figures 4 and 5 show alternative systems which avoid this drawback.

In Figure 4, the lines 13 and 14 from the motor 10 are not connected directly to the washer pump, but instead are connected to chambers 61, 62 on the two sides of a piston 60 actuating a valve member 45, which switches the lines 46, 47 to the washer pump air chambers alternately to a pressure port 48 or exhaust ports 49, 491. The pressure differential acting on the washer pump piston is then virtually equal to the pressure at the port 48, which is close to the full system pressure. A branch from the line 13 leads to a chamber 63, so that the areas acted on by pressures from lines 13 and 14 are the same.

The washer pump can be brought into action by a piston 40 controlled by a line 43 as illustrated, similar to that in Figure 3, but acting on the valve member 45 instead of on the washer pump piston. Alternatively, the line 14 between the motor and the chamber 61 could contain a valve 25 similar to that of Figure 1.

The system shown in Figure 5 depends for its action on the valve gear used to operate the motor 10. In automatically-reciprocating fluid-pressure motors, of which windscreen wiper motors are an example, one common method of operation is to cause the motor to move a pilot valve, which then operates a main vavle, which in turn reverses connec tions -to the motor. This is shown schematically in Figure 5, a pilot valve 50 switching end chambers 51, 52 of a main valve 53 between a pressure port 54 and exhaust ports 55, 551, causing the main valve 53 to reverse, which in turn causes -motor 10 two reverse. This type of valve gear is well known, though constructionally the valves can take a variety of forms.

In this sytem, the air chambers -in tbe washer pump are connected to the lines 56, 57 between the pilot valve and the main valve. As soon as the main valve 53 -has reversed, which is very solon after pilot valve 50 has -reversed, the pressure ,difFerential between lines 56 and 57 is virtually the pressure at port 54 of the pilot valve, and-this again is close to the full system pressure.

The-washer pump in Figure 5 could be brought into action by a spring-biased piston similar to that of Figure 3, acting on the washer pump piston. Alternatively, as shown in the drawings, the washer pump can be brought into action by a valve 25 similar to that of Figure 1, which connects the righthand air chamber in the washer pump to atmosphere for "off", and to line 56 for "on".

Figure 6 shows another variant, in which signals are again derived from a pilot valve 50 as in Fig. 5, but the actual air supply to the pump is from an intermediate valve as in Fig. 4. The pump, which is similar to that of previous figures, receives alternating pressure signals in its end chamber 21, 22 from a valve 45a, which consists of a spool portion and a larger diameter piston 60, the annulus 61a between the two being open to atmosphere.

The right hand side 62a of piston 60a is connected to output line 56 of pilot valve 50.

The left-hand side 65 of valve 45a is connected to a driver's control line 66, which is switched to exhaust when the washer pump is off, under which condition alternate pressure signals from line 56 will keep valve 45a to the left (as drawn), and the washer pump is inoperative.

The washer pump is brought into operation by connecting line 66 to pressure. Under that condition, when valve 50 is to the left as drawn) and line 56 is therefore to pressure, valve 45a remains to the left because of the difference in the areas exposed to pressure at its ends. When valve 50 reverses, line 56 is switched to exhaust and valve 45a moves to the right, causing the pump piston to move to the right, and signals to chambers 21 and 22 will reverse with each reversal of valve 45a, which will occur with each reversal of valve 50.

Fig. 7 shows an extension of the system of Fig. 6 to give washing and wiping of vehicle headlights as well as windscreen.

The washer pump output lines are connected as before to je;ts 70, 71 (each elf these repre sents a plural-ity of jets) on the-windscreen wiper arms or blades as before, but in add tion are connected through non-return valve 72, 73 to port 74 on a valve 75, Output line 76 of valve 45a Is connected to the left-hand side of actuators 77, 78 driving headlight wipers on .each side of the-yehicle. In the "off" configuration -as drawn, the righthand side these actuators is connected 'to atmosphere through a port 79, a valve 75 being to the left under the action of a bias spring 80.

To wash the yvindscreen only, line 66 is connected to pressure as before, and the system acts as in Fig. 6.

To v ash the windscreenand simultaneously wash and wipe the headlights, both line 66 and a line 81 are connected to pressure by the driver's control valve (not shown), and valves 45a and 75 will both move to the right. Washer jets 82 and 83 on the vehicle headlights are then connected via pert 84 to the pump output, and water will be sprayed on the headlights at the same time as on the windscreen.

The right-hand side of actuators 77 and 78 becomes connected to output line 85 of valve 45a via ports 79 and 86. The two sides of actuators 77 and 78 will then be connected alternately to pressure and exhaust as valve 45a reverses, i.e., as actuator 10 reverses, and the headlights will be wiped. To ensure that actuators 77 and 78 perform a full stroke, their speed is adjusted to give somewhat faster stroke than that of actuator 10.

In place of pistons, flexible diaphragms may be used in each system. The term "piston member" in the second paragraph of this specification is intended to include this possibility.

WHAT WE CLAIM IS:- 1. A windscreen wiper and washer system, including a compressed-air-operated wiper motor comprising valve gear and a first piston member (as herein defined) arranged to move to and fro between two chambers and thereby provide drive for a wiper; a pump comprising a second piston member and a third piston member coupled to move to and fro in unison between respective further chambers; conduits connecting the chambers at the two sides of the second piston member to receive respectively the air pressures from two places in the motor or in a further valve controlled by the motor, being places chosen so that the differential between the pressures varies cyclically in each cycle of operation of the motor; and further conduits for supply and discharge of washer liquid to and from the chambers at the two sides of the third piston member, and valves to ensure flow of liquid from supply to discharge when the third piston member moves to and fro.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. move a pilot valve, which then operates a main vavle, which in turn reverses connec tions -to the motor. This is shown schematically in Figure 5, a pilot valve 50 switching end chambers 51, 52 of a main valve 53 between a pressure port 54 and exhaust ports 55, 551, causing the main valve 53 to reverse, which in turn causes -motor 10 two reverse. This type of valve gear is well known, though constructionally the valves can take a variety of forms. In this sytem, the air chambers -in tbe washer pump are connected to the lines 56, 57 between the pilot valve and the main valve. As soon as the main valve 53 -has reversed, which is very solon after pilot valve 50 has -reversed, the pressure ,difFerential between lines 56 and 57 is virtually the pressure at port 54 of the pilot valve, and-this again is close to the full system pressure. The-washer pump in Figure 5 could be brought into action by a spring-biased piston similar to that of Figure 3, acting on the washer pump piston. Alternatively, as shown in the drawings, the washer pump can be brought into action by a valve 25 similar to that of Figure 1, which connects the righthand air chamber in the washer pump to atmosphere for "off", and to line 56 for "on". Figure 6 shows another variant, in which signals are again derived from a pilot valve 50 as in Fig. 5, but the actual air supply to the pump is from an intermediate valve as in Fig. 4. The pump, which is similar to that of previous figures, receives alternating pressure signals in its end chamber 21, 22 from a valve 45a, which consists of a spool portion and a larger diameter piston 60, the annulus 61a between the two being open to atmosphere. The right hand side 62a of piston 60a is connected to output line 56 of pilot valve 50. The left-hand side 65 of valve 45a is connected to a driver's control line 66, which is switched to exhaust when the washer pump is off, under which condition alternate pressure signals from line 56 will keep valve 45a to the left (as drawn), and the washer pump is inoperative. The washer pump is brought into operation by connecting line 66 to pressure. Under that condition, when valve 50 is to the left as drawn) and line 56 is therefore to pressure, valve 45a remains to the left because of the difference in the areas exposed to pressure at its ends. When valve 50 reverses, line 56 is switched to exhaust and valve 45a moves to the right, causing the pump piston to move to the right, and signals to chambers 21 and 22 will reverse with each reversal of valve 45a, which will occur with each reversal of valve 50. Fig. 7 shows an extension of the system of Fig. 6 to give washing and wiping of vehicle headlights as well as windscreen. The washer pump output lines are connected as before to je;ts 70, 71 (each elf these repre sents a plural-ity of jets) on the-windscreen wiper arms or blades as before, but in add tion are connected through non-return valve 72, 73 to port 74 on a valve 75, Output line 76 of valve 45a Is connected to the left-hand side of actuators 77, 78 driving headlight wipers on .each side of the-yehicle. In the "off" configuration -as drawn, the righthand side these actuators is connected 'to atmosphere through a port 79, a valve 75 being to the left under the action of a bias spring 80. To wash the yvindscreen only, line 66 is connected to pressure as before, and the system acts as in Fig. 6. To vçash the windscreenand simultaneously wash and wipe the headlights, both line 66 and a line 81 are connected to pressure by the driver's control valve (not shown), and valves 45a and 75 will both move to the right. Washer jets 82 and 83 on the vehicle headlights are then connected via pert 84 to the pump output, and water will be sprayed on the headlights at the same time as on the windscreen. The right-hand side of actuators 77 and 78 becomes connected to output line 85 of valve 45a via ports 79 and 86. The two sides of actuators 77 and 78 will then be connected alternately to pressure and exhaust as valve 45a reverses, i.e., as actuator 10 reverses, and the headlights will be wiped. To ensure that actuators 77 and 78 perform a full stroke, their speed is adjusted to give somewhat faster stroke than that of actuator 10. In place of pistons, flexible diaphragms may be used in each system. The term "piston member" in the second paragraph of this specification is intended to include this possibility. WHAT WE CLAIM IS:-

1. A windscreen wiper and washer system, including a compressed-air-operated wiper motor comprising valve gear and a first piston member (as herein defined) arranged to move to and fro between two chambers and thereby provide drive for a wiper; a pump comprising a second piston member and a third piston member coupled to move to and fro in unison between respective further chambers; conduits connecting the chambers at the two sides of the second piston member to receive respectively the air pressures from two places in the motor or in a further valve controlled by the motor, being places chosen so that the differential between the pressures varies cyclically in each cycle of operation of the motor; and further conduits for supply and discharge of washer liquid to and from the chambers at the two sides of the third piston member, and valves to ensure flow of liquid from supply to discharge when the third piston member moves to and fro.

2. A system according to claim 1, in

which the two places are on each side of the first piston member.

3. A system according to claim 1 or claim 2 including air-pressure-operated means for restraining the second piston member at one end of its stroke when desired.

4. A system according to claim 1, in which there is a said further valve, and the two places are two ports in this further valve, this valve also communicating with compressed air supply and exhaust and containing a valve member controlled by the differential pressure between the two chambers in the motor.

5. A system according to claim 4, including air-pressure-operated means for restraining the valve member of the further valve at one limit of its movement when desired.

6. A system according to claim 1, in which the motor includes a pilot valve actuated by movements of the first piston member, and a main valve controlled by the pilot valve and itself controlling connection of the two chambers of the motor to supply and exhaust, and the two places are in two controlling connections from the pilot valve to the main valve.

7. A system according to claim 1, in which the motor includes a pilot valve actuated by movements of the first piston member, and a main valve controlled by the pilot valve and itself controlling connection of the two chambers of the motor to supply and exhaust, and there is a said further valve, and the two places are two ports in this further valve, this valve also communicating with compressed air supply and exhaust and containing a valve member controlled by the differential pressure between two controlling connections from the pilot valve to the main valve.

8. A system according to claim 1, including a further discharge conduit and a further piston member, and a control valve by which, when desired, the flow of liquid to discharge is admitted also to the further discharge conduit and the air pressures from the two places in the motor or in the further valve are admitted to act on respective sides of the further piston member.

9. A system according to claim 1, substantially as described with reference to any one of Figures 1 to 7 of the accompanying drawings.