GB1569068A – Electric switches
– Google Patents
GB1569068A – Electric switches
– Google Patents
Electric switches
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Publication number
GB1569068A
GB1569068A
GB2158978A
GB2158978A
GB1569068A
GB 1569068 A
GB1569068 A
GB 1569068A
GB 2158978 A
GB2158978 A
GB 2158978A
GB 2158978 A
GB2158978 A
GB 2158978A
GB 1569068 A
GB1569068 A
GB 1569068A
Authority
GB
United Kingdom
Prior art keywords
housing
actuator member
contact
channel
contacts
Prior art date
1978-05-23
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB2158978A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ZF International UK Ltd
Original Assignee
Lucas Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
1978-05-23
Filing date
1978-05-23
Publication date
1980-06-11
1978-05-23
Application filed by Lucas Industries Ltd
filed
Critical
Lucas Industries Ltd
1978-05-23
Priority to GB2158978A
priority
Critical
patent/GB1569068A/en
1979-05-03
Priority to DE19792917821
priority
patent/DE2917821A1/en
1980-06-11
Publication of GB1569068A
publication
Critical
patent/GB1569068A/en
Status
Expired
legal-status
Critical
Current
Links
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Classifications
H—ELECTRICITY
H01—ELECTRIC ELEMENTS
H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
H01H1/00—Contacts
H01H1/12—Contacts characterised by the manner in which co-operating contacts engage
H01H1/14—Contacts characterised by the manner in which co-operating contacts engage by abutting
H01H1/16—Contacts characterised by the manner in which co-operating contacts engage by abutting by rolling; by wrapping; Roller or ball contacts
H—ELECTRICITY
H01—ELECTRIC ELEMENTS
H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
H01H1/00—Contacts
H01H1/58—Electric connections to or between contacts; Terminals
H01H1/5844—Electric connections to or between contacts; Terminals making use of wire-gripping clips or springs
H—ELECTRICITY
H01—ELECTRIC ELEMENTS
H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
H01H13/00—Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch
H01H13/02—Details
H01H13/12—Movable parts; Contacts mounted thereon
Description
(54) ELECTRIC SWITCHES
(71) We, LUCAS INDUSTRIES LIMITED, a British Company, of Great King Street, Birmingham. B19 2XF, 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 electric switches which are especially (but not exclusively) intended for use in controlling the operation of portable electrical appliances such as for example an electrically operated drill. One form of such an electric switch forms the subject of our prior Patent 1,314,335. In this patent there is described an electric switch having an insulating housing and an elongate actuator member also formed of insulating material and which is arranged to be linearly movable, relative to the housing, in directions parallel to its length. The housing has at least one pair of contact recesses which each contain a fixed contact, the two fixed contacts having contact-making portions which face each other across a channel formed in the housing, at least one of said contact-making portions being resiliently biased against a fixed abutment provided on the adjacent side of said channel. The elongate actuator member carries a contact which, during the aforesaid linear movement of said actuator member, will travel in said channel between an “on” position in which it will bridge said contactmaking portions of the fixed contacts to establish electrical connection therebetween and an “off” position in which said actuator member contact does not engage said contact-making portions of the fixed contacts. The actuator member contact conveniently comprises a short length of a metal (such as copper) tube and is arranged so that it is revolvable with respect to the actuator member about an axis perpendicular to the directions of movement of said actuator member. The actuator member is also of a size which is large enough to force the or each resiliently biased contact-making portion of said fixed contacts away from its associated fixed abutment when said actuator member contact engages and bridges said fixed contacts.
The base of the aforesaid channel formed in the housing will of course, like the housing, be formed of insulating material but the above described construction suffers from the disadvantage that metallic debris which in use will be formed by the relative movement between the actuator member and the fixed contacts will fall on to the bottom of said housing and may eventually accumulate to such an extent that a track or electrically conductive path will be formed across the bottom of said channel and will thus lead to a short-circuiting of the fixed contacts when the actuator member contact is in its “off” position. The provision of groove in the bottom of said channel for collecting such metallic debris does not solve the aforementioned problem because it is also common practice to use a lubricating grease in said channel and such grease will itself collect and hold the metalic debris so that eventually a short-circuiting path will be formed across the channel.
The object of the present invention there fore is to provide an improved construction in which there is less likelihood of a shortcircuiting path being formed as above-described so that the insulating material forming said channel will have a higher comparative tracking index as defined in B.S.
3781:1964.
In accordance with the present invention there is provided an electric switch comprising an insulating housing formed with at least one pair of recesses containing a pair of fixed contacts having contact-making portions which face each other across a channel formed in the housing, at least one of said portions being resiliently biased against a fixed abutment formed in the housing, the switch also having an insulating elongate actuator member which is linearly movable, relative to the housing, in directions parallel to its length and which carries at least one contact which, during said linear movement of said actuator member, will travel in said channel between an “on” position in which it will bridge said contact-making portions of the fixed contacts to establish electrical connection therebetween and an “off” position in which said actuator member contact does not engage said contact-making portions of the fixed contacts, characterised in that said actuator member contact comprises an electrically conductive element which is of cylindrical configuration externally and which is connected, at that end nearer to the bottom of said channel, to an electrically insulating pad which engages said channel bottom.
The invention will now be more particularly described with reference to the accompanying drawings wherein:
Figure 1 is a plan view of part of one example of an electric switch constructed in accordance with the present invention, this view depicting the switch in an “off” position,
Figure 2 is a cross-sectional view taken on the line 2-2 of Figure 1, and
Figure 3 is a partial cross-sectional view which shows one of the contacts carried by the actuator member when said contact is in an “on” position.
Referring to the drawings the switch shown therein includes a housing 10 conveniently formed as a moulding in an electrically insulating material. Said housing incorporates at least one pair of contact containing recesses indicated by reference numerals 11 and 12 and in fact in the switch now described there would be two such pairs of contact containing recesses (the other pair being generally similar to said recesses 11 and 12) although it is to be understood that a switch in accordance with the present invention need only have one such pair of recesses. There is also provided an elongate actuator member 13 which comprises an elongate stem 14 and a head portion 15 which in use is engageable by the thumb or finger of a user. Part of said stem 14 has been broken away in the plan view of
Figure 1 and said actuator member 13 is biased by a coil spring 16 into an “off” position as shown in Figure 1.
The aforesaid recesses 11 and 12 of the housing 10 contain respectively fixed contacts 17 and 18. Said fixed contacts 17 and 18 have contact-making portions which face each other across a channel 19 formed in said housing 10 and the bottom of said channel 19 may be provided with a groove 20. Furthermore at least one of said contact-making portions of the contacts 17 and 18 (or each of said contact-making portions if desired) is resiliently biased against a fixed abutment provided on the adjacent side of said channel 19. Thus in the example now described the contact 18 is bent to provide a loop which terminates in a blade-like portion 21 which engages an abutment 22 formed by a part of the moulding comprising the housing 10. Said portion 21 of the contact 18 will, in the “off” position of the switch as illustrated in Figure 1 be resiliently urged against said abutment 22 but in the “on” position of the switch, as shown in the scrap view of Figure 3 said portion 21 will be pushed away from said abutment 22 by means of a contact carried by the stem 14 of the actuator member 13 as will be hereinafter described.
Thus said stem 14 of the actuator member is formed with a pair of spaced downwardly facing notches which each receive a contact in the form of a roller 23 or 24 which is formed from a short length of a metal, such as for example copper tube.
Each of said contacts 23 and 24 is provided at its lower end with a downwardly depending pad of electrically insulating material, one such pad 25 which is connected to the contact 24 being seen in Figures 2 and 3.
The external periphery of each contacts 23 and 24 is of cylindrical configuration and similarly the external configuration of said pad 25 is also of external configuration but having a diameter which is smaller than the external diameter of the associated contact.
Conveniently each pad such as pad 25 is formed at its upper end with a portion of reduced diameter which is pressed into the adjacent end of the associated contact and in use the lower end of each pad will engage and slide over the bottom surface of said channel 19 formed in the housing 10.
In the “off” position of the switch which is illustrated in Figure 1 the actuator member 13 is biased by the spring 16 to a position in which the contact 24 carried by the stem 14 of said actuator member is disposed within said channel 19 in a position in which it does not engage with the contact-making portions of the contacts 17 and 18 and similarly the contact 23 also carried by said stem of the actuator member 13 will be disposed in a like position in relation to the other pair of fixed contacts that will be located in the other pair of recesses formed in said housing 10. On the other hand the switch can be set to an “on” position by pushing the actuator member 13 inwardly against the pressure exerted by the spring 16 until the contact 24 carried by the stem 14 of said actuator member bridges the contact-making portions of said contacts 17 and 18, said contact 24 being of a size which is sufficient to cause said portion 21 of the contact 18 to be pushed away from its abutment 22, thereby ensuring a good electrical connection between the contacts 17 and 18.
Such an “on” position of the contact 24 is shown in Figure 3 and the contact 23 would then be in a similar “on” position with respect to the other pair of fixed contacts located in the housing 10. There will also be provided, in known manner, a releasable latch member (not shown) mounted on the exterior of said housing for the purpose of releasably holding said actuator member 13 in its “on” position. There would also be provided for the housing 10 a cover, not shown, and in use connecting wires would be connected to the housing contacts in any convenient manner.
The provision of an insulating pad, such as pad 25, for each of the contacts carried by the elongate actuator member 13 will of course raise the contacts 23 and 24 themselves so that their lower ends (as seen in
Figures 2 and 3) will no longer engage the bottom surface of said channel 19 so that if arcing should occur between either of said contacts 23 and 24 and the associated fixed contacts when the switch is moved from an “on” position to an “off” position then a short circuit between the or each pair of fixed contacts is less likely to occur because of the greater distance between the position of any such arcs and the bottom surface of said channel 19 which may provide or tend to provide a leakage path. However any such leakage is much less likely to occur in any case since the provision of the aforesaid insulating pads 25 will tend to prevent the accumulation of metallic debris on said bottom surface of the channel 19, the lower end of each pad having the effect of sweeping said bottom surface of the channel so as to prevent the formation of an electrically conductive path across said surface.
WHAT WE CLAIM IS:- 1. An electric switch comprising an insulating housing formed with at least one pair of recesses containing a pair of fixed contacts having contact-making portions which face each other across a channel formed in the housing, at least one of said portions being resiliently biased against a fixed abutment formed in the housing, the switch also having an insulating elongate actuator member which is linearly movable, relative to the housing, in directions parallel to its length and which carries at least one contact which, during said linear movement of said actuator member, will travel in said channel between an “on” position in which it will bridge said contact-making portions of the fixed contacts to establish electrical connection therebetween and an “off” position in which said actuator member contact does not engage said contact-making portions of the fixed contacts, characterised in that said actuator member contact comprises an electrically conductive element which is of cylindrical configuration externally and which is connected, at that end nearer to the bottom of said channel, to an electrically insulating pad which engages said channel bottom.
2. An electric switch as claimed in Claim 1 characterised in that said housing is formed with two pairs of recesses containing fixed contacts, and said actuator member is provided with two contacts which in use and adapted respectively to co-act with the two pairs of fixed contacts contained in said two pairs of recesses.
3. An electric switch as claimed in
Claim 1 or Claim 2 wherein the or each electrically insulating pad connected to an actuator member contact has an external size which is smaller than that of the associated actuator member contacts
4. An electric switch substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (4)
**WARNING** start of CLMS field may overlap end of DESC **. then be in a similar “on” position with respect to the other pair of fixed contacts located in the housing 10. There will also be provided, in known manner, a releasable latch member (not shown) mounted on the exterior of said housing for the purpose of releasably holding said actuator member 13 in its “on” position. There would also be provided for the housing 10 a cover, not shown, and in use connecting wires would be connected to the housing contacts in any convenient manner. The provision of an insulating pad, such as pad 25, for each of the contacts carried by the elongate actuator member 13 will of course raise the contacts 23 and 24 themselves so that their lower ends (as seen in Figures 2 and 3) will no longer engage the bottom surface of said channel 19 so that if arcing should occur between either of said contacts 23 and 24 and the associated fixed contacts when the switch is moved from an “on” position to an “off” position then a short circuit between the or each pair of fixed contacts is less likely to occur because of the greater distance between the position of any such arcs and the bottom surface of said channel 19 which may provide or tend to provide a leakage path. However any such leakage is much less likely to occur in any case since the provision of the aforesaid insulating pads 25 will tend to prevent the accumulation of metallic debris on said bottom surface of the channel 19, the lower end of each pad having the effect of sweeping said bottom surface of the channel so as to prevent the formation of an electrically conductive path across said surface. WHAT WE CLAIM IS:-
1. An electric switch comprising an insulating housing formed with at least one pair of recesses containing a pair of fixed contacts having contact-making portions which face each other across a channel formed in the housing, at least one of said portions being resiliently biased against a fixed abutment formed in the housing, the switch also having an insulating elongate actuator member which is linearly movable, relative to the housing, in directions parallel to its length and which carries at least one contact which, during said linear movement of said actuator member, will travel in said channel between an “on” position in which it will bridge said contact-making portions of the fixed contacts to establish electrical connection therebetween and an “off” position in which said actuator member contact does not engage said contact-making portions of the fixed contacts, characterised in that said actuator member contact comprises an electrically conductive element which is of cylindrical configuration externally and which is connected, at that end nearer to the bottom of said channel, to an electrically insulating pad which engages said channel bottom.
2. An electric switch as claimed in Claim 1 characterised in that said housing is formed with two pairs of recesses containing fixed contacts, and said actuator member is provided with two contacts which in use and adapted respectively to co-act with the two pairs of fixed contacts contained in said two pairs of recesses.
3. An electric switch as claimed in
Claim 1 or Claim 2 wherein the or each electrically insulating pad connected to an actuator member contact has an external size which is smaller than that of the associated actuator member contacts
4. An electric switch substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
GB2158978A
1978-05-23
1978-05-23
Electric switches
Expired
GB1569068A
(en)
Priority Applications (2)
Application Number
Priority Date
Filing Date
Title
GB2158978A
GB1569068A
(en)
1978-05-23
1978-05-23
Electric switches
DE19792917821
DE2917821A1
(en)
1978-05-23
1979-05-03
ELECTRIC SWITCH
Applications Claiming Priority (1)
Application Number
Priority Date
Filing Date
Title
GB2158978A
GB1569068A
(en)
1978-05-23
1978-05-23
Electric switches
Publications (1)
Publication Number
Publication Date
GB1569068A
true
GB1569068A
(en)
1980-06-11
Family
ID=10165462
Family Applications (1)
Application Number
Title
Priority Date
Filing Date
GB2158978A
Expired
GB1569068A
(en)
1978-05-23
1978-05-23
Electric switches
Country Status (2)
Country
Link
DE
(1)
DE2917821A1
(en)
GB
(1)
GB1569068A
(en)
Cited By (1)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
GB2121619A
(en)
*
1982-04-30
1983-12-21
Lucas Ind Plc
Switch
1978
1978-05-23
GB
GB2158978A
patent/GB1569068A/en
not_active
Expired
1979
1979-05-03
DE
DE19792917821
patent/DE2917821A1/en
not_active
Withdrawn
Cited By (1)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
GB2121619A
(en)
*
1982-04-30
1983-12-21
Lucas Ind Plc
Switch
Also Published As
Publication number
Publication date
DE2917821A1
(en)
1979-11-29
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Legal Events
Date
Code
Title
Description
1980-08-28
PS
Patent sealed
1985-01-23
PCNP
Patent ceased through non-payment of renewal fee
