GB2350552A

GB2350552A - Heated washer assembly for motor vehicle glazing

Info

Publication number: GB2350552A
Application number: GB9912874A
Authority: GB
Inventors: Peter Lumsden
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1999-06-03
Filing date: 1999-06-03
Publication date: 2000-12-06
Also published as: GB2350555A; GB2350554A; GB2350556A; GB0011888D0; GB0011891D0; GB0011850D0; GB9912874D0

Abstract

A heated washer assembly for motor vehicle glazing comprises a screen wash reservoir (30) to store wash fluid, a spray nozzle (80) to direct wash fluid to a glazing component such as a windscreen or headlamp cover, fluid transfer tubing (50, 50') for conveying the wash fluid from the screen wash reservoir to the spray nozzle and a wiper blade 2 to remove the wash fluid and any dirt or entrained detritus from the glazing component. The use of a positive temperature coefficient of resistance plastics material to prevent problems which arise under low temperature conditions is disclosed. Each element of the washer assembly contains an insert or layer of this plastics material, <I>e.g.</I> core 4 of wiper blade 2, which, when an electric current is passed across it, heats up.

Description

2350552 Motor Mehick, Assenibly The present invention relates to a motor

vehicle glazing washer assembly, and more particularly to a number of disparate elements making up such a motor vehicle glazing washer assembly, A motor vehicle glazing washer assembly comprises a number of disparate elements; a screen wash reservoir to store washer fluid, a spray nozzle to direct washer fluid to a glazing component such as a windscreen or headlamp cover, fluid transfer tubing for conveying washer fluid form the screen wash reservoir to the spray nozzle, and a wiper blade to remove the washer fluid and any dirt or entrained detritus from the glazing component.

However, in cold conditions the washer fluid may freeze within the washing system and it may not be possible to operate the washer assembly. Also, the washer fluid may freeze on the glazing component on the gazing component to impair the operation of the wiper blade. In addition, ice formed on the glazing component may also impair the operation of the wiper blade.

A number of solutions to prevent freezing of the washer fluid in the washing system have been suggested. These include mounting the fluid reservoir near a heated component, such as the engine or exhaust. Similarly, it has been suggested that the fluid transfer tubing be mounted in close proximity to such a component to prevent freezing of the washer fluid within the fluid transfer tubing. It has also been suggested to heat the fluid transfer tubing by the use of a resistance wire.

A number of designs of spray nozzle incorporating a heating element adjacent a washer fluid outlet are known. However, the construction of such nozzles is complex, and such nozzles have a relatively high unit cost.

A number of solutions to improve operation of the wiper blade in cold conditions have been suggested. These include providing a cavity extending along a longitudinal axis of a plastics wiper blade into which a heating element is introduced. The heating element is used to heat the plastics of the wiper blade, for example, to prevent the build up of ice on the wiper blade. It is a problem of such constructions that the forming of the cavity adds complexity to the wiper blade. It is a further problem that introducing the heating element into the cavity is a time consuming step that increases the manufacturing time of such wiper blades in comparison to solid plastics wiper blades.

It is an advantage of the present invention that it eliminates, or at least substantially 10 reduces at least some of the problems identified above.

1 According to a first aspect of the present invention, a wiper blade having an extemal profile comprises a core of positive coefficient of resistance plastics material enclosed by a rubber or thermoplastics sheath, the sheath defining the external profile of the wiper blade. The wiper blade may conveniently be manufactured by coextruding the sheath over the core.

!5 According to a second aspect of the present invention, a screen wash reservoir comprises an inner wall, an outer wall and an intermediate wall disposed between the inner wall and the outer wall, in which the intermediate wall comprises a plastics material having a positive temperature coefficient of resistance According to a third aspect of the present invention, screen wash transfer tubing 20 comprises a tubular member having an inner surface defining a passageway through which fluid may pass and an outer surface, a thickness defined between the inner surface and the outer surface, in which the tubular member further comprises a plastics material having a positive temperature coefficient of resistance located within the thickness.

According to a forth aspect of the present invention, spray nozzle comprises a body portion and an insert, in which the body comprises a recess for receiving the insert and a passageway extending through a region of the washer nozzle adjacent the recess, and in which the insert comprises a plastics material having a positive temperature coefficient of resistance The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure I shows a section of a wiper blade according to a first aspect of the present invention along line I-I of Figure 2; Figure 2 shows a side view of the wiper blade of Figure 1; Figure 3 shows a section of a screen wash reservoir according to a second aspect of the present inention; Figure 4 shows a side view of screen wash transfer tubing according to a third aspect of the present invention; Figure 5 shows a section along line V-V of Figure 4; Figure 6 shows a section along an alternative embodiment of transfer tubing according to the third aspect of the present invention; and Figure 7 shows a side section of a spray nozzle according to a forth aspect of the present invention.

Referring first to Figures I and 2, there can be seen a wiper blade 2 according to a first aspect of the present invention. The wiper blade 2 is adapted to be fitted to a wiper blade assembly of a motor vehicle. The wiper blade 2 comprises an elongate member. The elongate member comprises a core 4 of an electrically conductive heatable plastics material enclosed by a sheath 6 of plastics material. The plastics material of the core 4 is one having a positive temperature coefficient of resistance. The plastics material of the sheath 6 may conveniently comprise a known electrically non-conductive material for the manufacture of wiper blades such as a rubber or a thermoplastic.

The sheath defines the exterrial profile of the wiper blade. The wiper blade 2 comprises a carrier portion 8 for receipt within a wiper blade carrier, and a blade portion 10 depending therefrom. The carrier portion includes first and second slots 12,14, one to each side of the carrier portion. In use the slots 12,14 carry reinforcing elements (not shown), such as metal 5 strips, used to stiffen the wiper blade along a longitudinal axis thereof.

First and second electrical contacts 16,18 are introduced into the core 4 through the sheath 6 to place the core material in an electrical circuit. The circuit may be operated by any convenient means, for example by an electrical control unit (not shown) which may operate the electrical circui9t in response to a number of stimuli, for example a temperature sensor, a user operated switch operated from within a passenger cell of the motor vehicle to which the wiper blade assembly including the wiper blade of the present invention is fitted.

First and second sealing means 20,22 are provided at first and second ends of the core 4. Preferably, the core 4 runs through the carrier portion 8 of the elongate member, such that the first and second sealing means are provided at each end of the carrier portion.

In use, when an electric current is passed across the core, the core 4 will heat up. The core 4 will in turn heat the material of the sheath 6 to prevent freezing of the wiper blade 2 to a glazing component of the motor vehicle to which it is fitted, or to unfreeze the wiper blade 2 from the glazing component prior to operation of the wiper blade assembly. In addition, heating of the material of the sheath 6 by the core 4 can be used to prevent stiffening of the wiper blade 2 in cold environments.

To avoid unnecessary complication in the manufacture of the wiper blade, the core 4 and the sheath 6 may conveniently be coextruded. The construction of the wiper blade 2 in this manner has as an advantage that there is no need to form the wiper blade 2 with a cavity, and no need to spend time threading or otherwise inserting a heating element into the wiper blade 2. The construction of the wiper blade in this manner has as a further advantage that no metal components are contained within the wiper blade. As a result the wiper blade can more easily be recycled since there are no metallic parts to be removed from the wiper blade.

Referring now to Figure 3, there can be seen a screen wash reservoir 30 according to a second aspect of the present invention. The screen wash reservoir 30 may be of any shape required. The screen wash reservoir 30 is provided with an opening 32 at an upper part through which screen wash 34 may be introduced into the screen wash reservoir. Preferably, the opening is provided with releasable sealing means 36, for example a screw cap. The screen wash reservoir 30 comprises an inner wall 38, an outer wall 40 and an intermediate wall 42 disposed between the inner wall and the outer wall.

The 'intermediate wall 42 comprises a plastics material having a positive temperature coefficient of resistance. The inner wall and the outer wall may be of any suitable insulating plastics material. The inner wall 38 should be resistant to any additive contained within the screen wash to be contained therein. The outer wall 40 should be resistant to external environmental conditions.

First and second electrical contacts 44,46 are introduced into the material of the intermediate wall 42 through the outer wall 40 to place the intermediate wall material in an electrical circuit. The circuit may be operated by any convenient means, for example by an electrical control unit (not shown) which may operate the electrical circuit in response to a number of stIMUli, for example a temperature sensor, a user operated switch operated from within a passenger cell of the motor vehicle to which the screen wash reservoir 30 of the present invention is fitted.

In use, when an electric current is passed across the intermediate wall, the intermediate wall will heat up. The intermediate wall 42 will in rum heat the material of the inner wall to prevent freezing of the screen wash 34 contained within the screen wash reservoir 30 thereby ensuring a ready supply of screen wash without requiring that the screen wash reservoir be mounted near a heated component such as a motor vehicle engine or exhaust.

The screen wash reservoir may be formed by any suitable means. For example, it may be formed by blow moulding of a tube of coextruded plastics. Alternatively, the reservoir may be produced as a result of sequential component injection; the outer wall material being injected first into a mould cavity, the material of the intermediate wall 42 being introduced behind the outer wall material, the inner wall material being injected behind the intermediate wall material, and a gas being injected behind the inner wall material to spread the three layers evenly over the mould cavity.

The screen wash reservoir 30 of the present invention has as an advantage that no metal components are contained within the screen wash reservoir. As a result the screen wash reservoir can more easily be recycled since there are no metallic parts to be removed from the screen wash reservoir.

Referring now to Figures 4 and 5, there can be seen screen wash transfer tubing 50 according to a third aspect of the present invention. The screen wash transfer tubing comprises an elongate tubular member. The transfer tubing may be of any desirable crosssection. The tubing 50 comprises a first tubular member 52 of a first flexible plastics material. The tubing has an inner surface 54 and an outer surface 56 Miming a thickness therebetween. Within the thickness of the first tubular member 52 there is formed a second member 58.

In the embodiment shown in Figures 4 and 5, the first tubular member 52 is formed as a generally circular tube 62 having a passage through which screen wash 60 may flow and a rib 64 extending along the length of the transfer tubing. The second member 58 is located within the rib.

The second member 58 comprises a plastics material having a positive temperature coefficient of resistance. The flexible plastics material may comprise any suitable insulating plastics material. The flexible plastics material should be resistant to any additive contained within the screen wash passing through the tubing and also should be resistant to external 5 environmental conditions.

With reference to Figure 4, first and second electrical contacts 66,68 are introduced into the second member 58 through the outer surface 56 of the tubular member to place the second member 58 in an electrical circuit. The circuit may be operated by any convenient means, for example by an electrical control unit (not shown) which may operate the electrical circuit in response to a number of stimuli, for example a temperature sensor, a user operated switch operated from within a passenger cell of the motor vehicle to which the wiper blade assembly including the transfer tubing 50 of the present invention is fitted.

In use, when an electric current is passed across the second member, the second member will heat up. The second member will in turn heat the material of the tubular member to prevent freezing of any screen wash contained within the transfer tubing.

The screen wash transfer tubing may be formed by any suitable means. For example, the transfer tubing may be produced by coextruding the plastics of the tubular member 52 about the second member 58.

An alternative embodiment of the tubing is shown in Figure 6. In this embodiment, the transfer tubing SO' is generally circular in cross section and has an eccentrically located passageway 70 through which screen wash 60' may flow. The second member 58' is located within that portion of the transfer tubing SO' having greatest thickness.

The screen wash transfer tubing of the present invention has as an advantage that no metal components are contained within the screen wash tubing. As a result the screen wash tubing can more easily be recycled since there are no metallic parts to be removed from the screen wash tubing, Referring now to Figure 7, there can be seen a washer spray nozzle 80 according to a last aspect of the present invention. The washer spray nozzle 80 is adapted to be fitted in an opening in a body panel of a motor vehicle, for example in a vehicle bonnet panel. The washer nozzle includes a heating member. The heating member comprises an insert 82 of an electrically conductive heatable plastics material. The plastics material of the insert 82 is one having a positive temperature coefficient of resistance, The remainder of the washer nozzle conveniently comprises a plastics material. The plastics rriaterial of the remainder of the nozzle may conveniently comprise a known electrically non-conductive material for the manufacture of washer nozzles such as a rubber or a thermoplastic. The remainder of the washer nozzle includes a recess 84 into which the insert may be received, and a passageway 86 extending through a region of the washer nozzle adjacent the recess. The remainder of the spray nozzle also includes means 88 for attaching the spray nozzle to a motor vehicle and means 90 for retaining the spray nozzle in position against a motor vehicle body panel.

First and second electrical contacts 92,94 are introduced into the insert to place the insert material in an electrical circuit. The circuit may be operated by any convenient means, for example by an electrical control unit (not shown) which may operate the electrical circui9t in response to a number of stimuli, for example a temperature sensor, a user operated switch operated from within a passenger cell of the motor vehicle to which the washer nozzle assembly including the washer nozzle 80 of the present invention is fitted.

In use, when an electric current is passed across the insert, the insert 82 will heat up.

The insert 82 will in turn heat the material of the nozzle in the region of the passageway 86 to prevent freezing of any washer fluid in the washer nozzle. This prevents frozen fluid from forming a plug in the passageway 86, thereby preventing operation of the washer nozzle.

The insert 82 may be readily removable from the washer nozzle thereby to allow the components of the washer nozzle assembly to be recycled.

1 - 10ClAW 1 A wiper blade having an external profile comprising a core of positive coefficient of resistance plastics material enclosed by a rubber or thermoplastics sheath, the sheath defining the external profile of the wiper blade.

2. A wiper blade according to claim 1, in which the wiper blade comprises a carrier portion for receipt within a wiper blade carrier, and a blade portion depending therefrom, characterised in that the core runs through the carrier portion of the wiper blade.

3. A wiper blade substantially as described herein with reference to and a illustrated in Figutes 1 and 2 of the accompanying drawings.

4. A method of manufacture of a wiper blade according to any previous claim, characterised in that it comprises the steps of coextruding the sheath over the core.

5. A screen wash reservoir comprising an inner wall, an outer wall and an intermediate wall disposed between the inner wall and the outer wall, in which the intermediate wall comprises a plastics material having a positive temperature coefficient of resistance.

6. A screen wash reservoir substantially as described herein with reference to and as illustrated in Figure 3 of the accompanying drawings.

7. Screen wash transfer tubing comprising a tubular member having an inner surface defining a passageway through which fluid may pass and an outer surface, a thickness defined between the inner surface and the outer surface, in which the tubular member further comprises a plastics material having a positive temperature coefficient of resistance located within the thickness.

8. Screen wash transfer tubing substantially as described herein with reference to and as illustrated in Figures 4, 5 and 6 of the accompanying drawings.

9. A spray nozzle comprising a body portion and an insert, in which the body comprises a recess for receiving the insert and a passageway extending through a region of the washer nozzle adjacent the recess, and in which the insert comprises a plastics material having a positive temperature coefficient of resistance.

10. A spray nozzle substantially as described herein with reference to and as illustrated in Figure 7 of the accompanying drawings.