The subject of the invention is a motor, particularly for an automobile windscreen wiper mechanism. The motor which is the subject of the invention may also be utilized as a motor for windscreen washer pumps, alternators, hybrid drives, cooler fans and in other motor applications, chiefly electric motors operating in a watery or moist environment.
Windscreen wiper systems are driven by electric motors with a transmission system (
One of the major technical problems that arises when the solution described above is used is water vapour being sucked through the deaeration membrane (3) into the casing (1,2) during cooling of the motor. This vapour condenses inside the casing, and when the motor is re-started and gets warm, the condensed water begins to boil at a temperature of around 100° C., causing a sudden jump in pressure which may damage the casing seal (4).
Electric motors with a membrane that lets through gas, or with sealing using seals, are leaktight during operation usually only with minor underpressure. During operation, motors achieve high temperatures, e.g. in the case of windscreen wiper motors these are temperatures of the order of 130° C., and in the event of sudden contact with water, e.g. when the vehicle drives into a water obstacle, they rapidly cool down. When this happens the pressure inside the motor falls drastically, which often causes water to be sucked in through defects in the seal, including through a goretex membrane. Leaktightness tests on contact with water or a flow of water are governed by standards, e.g. IEC 60529, or DIN 40050-9, but they do not currently envisage tests with multiple heating and immersion of the motor in cold water during operation. Multiple heating tests and motor immersion in cold water or spraying them from every direction are conducted by some motor or vehicle manufacturers, and most of the solutions that are currently known, including motors with a vacuum inside the casing, accumulate considerable quantities of water internally during the test.
This problem has been successfully solved by providing the potential to adjust the pressure inside the motor using a reversibly deforming element which enables the volume of the internal space to be enlarged by deformation of this element under the influence of the pressure exerted on the casing.
The essence of the invention is a motor, particularly for an automobile windscreen wiper mechanism, which contains a casing which defines the internal space, characterized in that the internal space of the motor is partially limited by a reversibly deforming element which enables the volume of the space inside the motor to be altered under the influence of the pressure exerted on the casing.
Preferably the motor contains a transmission casing and a motor casing where the reversibly deforming element is on the transmission casing and/or on the motor casing and/or between the motor casing and the transmission casing.
Preferably the reversibly deforming element is made of a material that does not allow air to pass through, preferably an elastomer.
Preferably the reversibly deforming element is an elastic membrane.
Preferably the motor contains a blocking element preventing ingestion of the elastic membrane into the inside of the casing.
Preferably the blocking element is located on the transmission casing and/or on the motor casing and/or between the motor casing and the transmission casing.
Preferably the motor contains a rigid casing part and a reversibly deforming element, preferably an elastic membrane, sealing off the space inside the motor and enabling the volume of the space inside the motor to be enlarged by deformation of the reversibly deforming element under the influence of the pressure exerted on the casing by the gas which is inside it.
Preferably the motor contains a blocking element in the form of a tongue fastened to the inside surface of the rigid part of the casing and at least partially located in the inside diameter of the opening in the rigid part of the casing, which is covered by the reversibly deforming element in the form of an elastic membrane.
Preferably in the part that is located in the inside diameter of the opening the blocking element possesses openings.
Preferably the reversibly deforming element is an elastic membrane fastened to the cover and/or on the bottom element of the rigid part of the transmission casing.
Preferably the reversibly deforming element is an elastic membrane fastened inside the rigid part of the casing and attached to the inside surface of the rigid part of the casing and/or to the was forming the equalizing tank (9) around the opening in the rigid part of the casing, attached to or constituting part of the internal surface of the rigid part of the casing.
Preferably the reversibly deforming element forms the lid of the rigid part of the transmission casing.
Through use of a reversibly deforming element it is possible to control the pressure inside the motor and lower the risk of seal failure. This is responsible for a drastic reduction in gas exchange between the internal space and the environment surrounding it—water does not get inside in the form of water vapour, or else gets in in a small quantity (through defects in the seal arising, for example, during use or while under load). The pressure inside the casing is adjusted by an increase in the volume caused by deformation of the reversibly deforming element under pressure exerted by the gas which is located in the space inside the motor.
Because there are no pressure jumps caused by the boiling of water that has got inside in such a motor, the seal for such a casing may be designed to be less resistant to pressure or underpressure in its internal space (and thus less expensive) than the seals used in solutions with a deaerating watertight membrane or those sealed using permanent sealing elements.
The invention will now be presented in more detail in favourable examples of its manufacture, with reference to the appended figures, where:
The membrane may also be fastened inside the casing of the transmission (2) and/or the motor (1) (
In another, non-illustrated example, the reversibly deforming element (5) is not a membrane, but a rigid element, which may take at least two positions—concave (in the direction of the internal space of the motor) and convex, like the caps for jars of the “twist-off click” type, fitted with an element used to check whether the jar, and especially one containing food products, has been opened (known as a safety button in English). Such an element may be located on the transmission casing (2) or the motor casing (1), or constitute a tongue on the rigid part of the transmission box casing (2).
The examples shown do not narrow the scope of the required protection down only to motors for an automobile windscreen wiper mechanism. Motors as in the invention may find application in any place where it is best to protect a motor from moisture.
Number | Date | Country | Kind |
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P.414018 | Sep 2015 | PL | national |