GB1572009A - Drive assembly providing a reciprocatory output primarily for use with motor vehicle auxiliary equipment - Google Patents

Description

(54) A DRIVE ASSEMBLY PROVIDING A RECIPROCATORY OUTPUT,PRIMARILY FOR USE WITH MOTOR VEHICLE AUXILIARY EQUIPMENT (71) We, DUCELLIER & CIE, a French Body Corporate of Echat 950, 94024 Creteil Cedex, France, 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 the following statement: This invention relates to a drive assembly including a housing constituted by two hollow housing portions and enclosing an electric motor, a worm screw mechanism operatively connected to the motor and having a worm and tangentially disposed gear wheel engaged with the worm, a rod and crank system which is displaceable by said gear wheel to cause an output shaft to perform an oscillatory movement for transmission to a device when connected to the free end of the output shaft, and an end of travel stop switch controlled by the rod and crank system. The assembly of the invention is particularly applicable to vehicle equipment such as windscreen or headlamp wiper mechanisms.

Drive assemblies are already known in which the main elements mentioned above are housed in a single housing with the shaft of the worm screw, which is fast for rotation with the motor, forming an extension of the armature shaft of the said motor. As a result there is a length dimension which is often incompatible with the space available in a vehicle to house the drive assembly.

Moreover, the fact that the reduction ratio of the worm screw mechanism is limited, necessitates a motor of a certain power in order to obtain the necessary torque, and as a result a certain size of motor.

An object of the present invention is to provide an improved drive assembly of compact shape and reduced dimensions as compared with some conventional mechanisms of similar type.

According to the invention, a drive assembly comprises a housing constituted by two hollow housing portions and enclosing an electric motor, a worm screw mechanism operatively connected to the motor and having a worm and tangentially disposed gear wheel engaged with the worm, a rod and crank system which is displaceable by said gear wheel to cause an output shaft to perform an oscillatory movement, and an end of travel stop switch controlled by the rod and crank system, the shaft of the worm screw being disposed parallel to the shaft of the motor in the plane of the joint of the two hollow portions of the casing, and being operatively connected to the said motor by means of a reduction gear.

The invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 shows a plan view of a drive assembly of the invention, of which the upper hollow portion has been removed for a better understanding of the drawing, Figure 2 shows a view in section taken along the line II-II of Figure 1, Figure 3 shows a view in section taken along the line III-III of Figure 1, Figure 4 is a view in section taken along the line IV-IV of Figure 1.

Referring to the drawings, the drive assembly therein shown has a motor 1 of which the end of the armature shaft carries the drive pinion 2 of a reduction gear, the pinion being engaged with an intermediate pinion 3, itself engaged with a driven pinion 4. The driven pinion 4 is fast for rotation with the shaft of a worm screw 5 of a worm screw reduction mechanism, of which a tangentially disposed gear wheel 6 transmits an oscillatory movement of predetemined angular displacement to an output shaft 7 by means of a rod and crank system.

The rod and crank system, shown more clearly in Figure 3 includes a rod 8, one end of which articulates about a crank pin 9 eccentric with respect to the gear wheel 6.

The other end of the rod 8 articulates about a shaft 10 passing through the end formed as a devils, of a crank 12 pivoting at its other end about a fixed axis 13. A secondary rod 14 articulating about the shaft 10 connects the end of the crank 12 to the end of a second crank 15 which carries a shaft 16 about which rod 14 articulates. The crank 15 is fast for rotation at its other end with the output shaft 7 to which it communicates an oscillatory movement. The shaft 10 is extended at 11 in order to control an end of travel stop switch 17 when the crank 12 pivots.

All the elements which have just been described are housed in a casing 18 constituted by two hollow portions 19 and 20 in the plane of the joint 21 of which lie the respective axes 3a and Sa of the intermediate pinion 3 and the shaft of the worm screw 5 parallel to the shaft of the motor 1. The motor 1 is supported by an insulating cradle 22 disposed at the base of the lower hollow portion 20 and is held in place when the upper hollow portion 19 is assembled. The insulating cradle 22 can support the various connecting terminals of the assembly, as well as the end of travel stop switch 17.

A drive assembly of compact shape and dimensions is thus obtained, on the shaft 7 of which may be fixed a wiper blade, particularly for the cleaning of windscreens or headlamps of motor vehicles.

WHAT WE CLAIM IS: 1. A drive assembly comprising a housing constituted by two hollow housing portions and enclosing an electric motor, a worm screw mechanism operatively connected to the motor and having a worm and tangentially disposed gear wheel engaged with the worm, a rod and crank system which is displaceable by said gear wheel to cause an output shaft to perform an oscillatory movement, and an end of travel stop switch controlled by the rod and crank system, the shaft of the worm screw being disposed parallel to the shaft of the motor in the plane of the joint of the two hollow portions of the casing and being operatively connected to the said motor by means of a reduction gear.

2. A drive assembly according to Claim 1, wherein the reduction gear includes a drive pinion fast for rotation with the armature of the motor and in engagement with an intermediate pinion, itself in engagement with a driven pinion fast for rotation with the shaft of the worm screw.

3. A drive assembly according to Claim 1 wherein the rod and crank system is constituted by a rod of which one of the ends articulates about a crank pin eccentric with respect to the gear wheel and the other about a shaft at the free end of a first crank pivoting about a fixed axis in such a manner as to transmit an oscillatory movement to the first crank, and a second rod which pivotally connects together the free ends of the first crank and of a second crank fast for rotation with the output shaft, and transmits an oscillatory movement to the latter and consequently to the output shaft.

4. A drive assembly according to any one of Claims 1 to 3, wherein the end of travel stop switch is operatively engageable by an extension of the shaft about which the two rods at the free end of the first crank articulate.

5. A drive assembly according to Claim 1, wherein the motor is supported by an insulating cradle disposed at the base of the normally lower hollow housing portion and on or in which are disposed the electrical connecting terminals and the end of travel stop switch.

6. A drive assembly according to any one of the preceding claims adapted for connection or connected to a vehicle windscreeen wiper.

7. A drive assembly substantially as hereinbefore described with reference to the accompanying drawings.

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

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. eccentric with respect to the gear wheel 6. The other end of the rod 8 articulates about a shaft 10 passing through the end formed as a devils, of a crank 12 pivoting at its other end about a fixed axis 13. A secondary rod 14 articulating about the shaft 10 connects the end of the crank 12 to the end of a second crank 15 which carries a shaft 16 about which rod 14 articulates. The crank 15 is fast for rotation at its other end with the output shaft 7 to which it communicates an oscillatory movement. The shaft 10 is extended at 11 in order to control an end of travel stop switch 17 when the crank 12 pivots. All the elements which have just been described are housed in a casing 18 constituted by two hollow portions 19 and 20 in the plane of the joint 21 of which lie the respective axes 3a and Sa of the intermediate pinion 3 and the shaft of the worm screw 5 parallel to the shaft of the motor 1. The motor 1 is supported by an insulating cradle 22 disposed at the base of the lower hollow portion 20 and is held in place when the upper hollow portion 19 is assembled. The insulating cradle 22 can support the various connecting terminals of the assembly, as well as the end of travel stop switch 17. A drive assembly of compact shape and dimensions is thus obtained, on the shaft 7 of which may be fixed a wiper blade, particularly for the cleaning of windscreens or headlamps of motor vehicles. WHAT WE CLAIM IS:

1. A drive assembly comprising a housing constituted by two hollow housing portions and enclosing an electric motor, a worm screw mechanism operatively connected to the motor and having a worm and tangentially disposed gear wheel engaged with the worm, a rod and crank system which is displaceable by said gear wheel to cause an output shaft to perform an oscillatory movement, and an end of travel stop switch controlled by the rod and crank system, the shaft of the worm screw being disposed parallel to the shaft of the motor in the plane of the joint of the two hollow portions of the casing and being operatively connected to the said motor by means of a reduction gear.

2. A drive assembly according to Claim 1, wherein the reduction gear includes a drive pinion fast for rotation with the armature of the motor and in engagement with an intermediate pinion, itself in engagement with a driven pinion fast for rotation with the shaft of the worm screw.

3. A drive assembly according to Claim 1 wherein the rod and crank system is constituted by a rod of which one of the ends articulates about a crank pin eccentric with respect to the gear wheel and the other about a shaft at the free end of a first crank pivoting about a fixed axis in such a manner as to transmit an oscillatory movement to the first crank, and a second rod which pivotally connects together the free ends of the first crank and of a second crank fast for rotation with the output shaft, and transmits an oscillatory movement to the latter and consequently to the output shaft.

4. A drive assembly according to any one of Claims 1 to 3, wherein the end of travel stop switch is operatively engageable by an extension of the shaft about which the two rods at the free end of the first crank articulate.

5. A drive assembly according to Claim 1, wherein the motor is supported by an insulating cradle disposed at the base of the normally lower hollow housing portion and on or in which are disposed the electrical connecting terminals and the end of travel stop switch.

6. A drive assembly according to any one of the preceding claims adapted for connection or connected to a vehicle windscreeen wiper.

7. A drive assembly substantially as hereinbefore described with reference to the accompanying drawings.