Electricity: motive power systems – Periodic – repetitious or successive operations control of...
Patent
1988-04-11
1989-08-15
Shoop, Jr., William M.
Electricity: motive power systems
Periodic, repetitious or successive operations control of...
318444, 318466, 318467, 200 6154, 307 101, H02P 104
Patent
active
048578150
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a switch for energizing an electric motor of a wiper system.
A switch of this kind is known from practice. Starting from a parking position the switch is adjustable by turning a switch lever in three successive operating positions. The first operating position thereby corresponds to an intermittent mode of operation in which a wiping action with a low wiper speed interrupted by interval times is effected. The following operating position corresponds to a first mode of continuous operation, in which a continuously low wiper speed is effected and the then following position corresponds to a second mode of continuous operatio in which a continuously high wiper speed is effected. The stationary contacts associated with the two modes of continuous operation of this construction are arranged one behind the other on a first contact path, whereas the stationary contacts associated with the intermittent mode of operation are located on a second contact path positioned beside the first contact path. The stationary contacts on the first contact path can thereby be acted upon in pairs by a first bridging contact and the stationary contacts on the second contact path can be acted upon in pairs by a second bridging contact. A disadvantge of this switch is that upon a failure of a pair of stationary contacts or of a part of this pair the associated mode of operation can no longer be effected. It is true that a failure of this kind does not happen very frequently in practice, however recently switches have been increasingly required in which a failure of this kind is even less probable and which therefore have an increased operational reliability in comparison with customary switches.
SUMMARY OF THE INVENTION
It is an object of the present invention to create a switch of the initially mentioned kind having an increased operational reliability, in particular with regard to the possible failure of a pair of stationary contacts or a part thereof.
This object is solved by a switch including the feature of the characterizing part of claim 14. There is only little risk for a stationary contact associated to the same mode of operation to fail simultaneously on both contact paths.
This is why a very high operational reliability is ensured in a switch according to the invention.
By a development according to claim 15 the operational reliability is even improved, because the current load per stationary contact is reduced to a half, so that the service life of this embodiment is theoretically doubled.
The parallel circuit can constructively be realized by making the two bridging contacts conductive in the same operating position. If the switch, as is customary, has operating positions for continuous operation with low and high wiper speed it is recommended to provide the measure(s) according to the invention for the mode of operation with slow wiper speed, because according to experience this wiper speed is needed more frequently than high wiper speed.
If the switch also has a position for tip-wiper operation which, according to experience, is also frequently needed, it is recommended to provide the measure(s) according to the invention also for this mode of operation. If the position for tip-wiper operation is adjacent to the position for continuous operation with low wiper speed the same stationary contacts can be used.
By the measure according to claim 18 it is achieved that the electric motor is not switched off during changeover from low to high wiper speed and the windshield wiper/or wipers do not stop in the meantime. The operator is thus prevented from being irritated.
BRIEF DESCRIPTION OF THE DRAWING
The invention is described below in detail by way of the accompanying drawing, in which:
FIG. 1 is a diagram for energizing an electric motor of a wiper system according to the prior art,
FIG. 2 is a view on the base plate of a first switch according to the invention,
FIG. 3 is a top view on the switching element of a first switch according to the invention,
FIG. 4 is
REFERENCES:
patent: 3593090 (1971-07-01), Kearns
patent: 4328431 (1982-05-01), Usami
patent: 4585980 (1986-04-01), Gille et al.
patent: 4607198 (1986-08-01), Tsunoda
patent: 4670695 (1987-06-01), Licata et al.
patent: 4710878 (1987-12-01), Iyoda
Erdelitsch Herbert
Machalitzky Otto
Prang Josef-Elmar
Ip Paul
Seitter Robert P.
Shoop Jr. William M.
SWE Auto-Electric GmbH
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