Patent Publication Number: US-6655720-B2

Title: Lock with plunger unit

Description:
FIELD OF INVENTION 
     This invention relates to locks for preventing one member from sliding relative to another member. One of the members may for example be a patio door, a window or a cupboard door, with the other member being an associated frame member. 
     BACKGROUND OF INVENTION 
     Many such locks are known, but there is still a need for an improved lock of this kind which is more effective than known locks but which nevertheless is relatively simple and not unduly expensive. 
     It is therefore an object of the invention to provide an improved lock of this kind. 
     SUMMARY OF INVENTION 
     According to the invention, a lock for preventing one member from moving relative to another member has a housing securable to one member and a plunger unit mounted in the housing. The plunger unit has a sleeve, a plunger slidably mounted in the sleeve, and a spring acting between the plunger and the sleeve to resiliently bias the plunger to a locking position in which a free end portion of the plunger projects from one end of the sleeve, the plunger also having a manually operable portion projecting from an opposite end of the sleeve. In the locking position, the free end portion of the plunger projects from the housing to extend into an aperture in the other member, when the housing is secured to said one member, and thereby prevent relative sliding movement between the members. The plunger also has an unlocking position in which the free end portion thereof is withdrawn from the aperture in the other member by pulling the manually operable portion against the action of the spring. The housing may include a main portion and a cover portion removably securable thereto, the main portion and the cover portion having longitudinally extending recesses receiving the plunger unit. The cover portion may be attachable to the main portion by sliding movement relative thereto, and the cover portion and the housing portion may have mutually engaging keyways to enable the sliding movement to be effected 
     The spring may be a helical spring which surrounds the plunger within the sleeve. 
     The manually operable portion and the free end portion of the plunger may be separate parts secured together by screw-threaded engagement, the separate parts being separable to enable the spring to be assembled with the plunger and the sleeve. 
     The sleeve and the housing may have inter-engaging means to prevent movement of the sleeve relative to the housing. A plurality of longitudinally-spaced inter-engaging means may be provided to enable the amount of projection of the free end portion of the plunger from the housing to be adjusted. 
     The manually operable portion of the plunger and the sleeve may have stop means which are mutually engageable by rotation of the manually operable portion of the plunger relative to the sleeve when the plunger is in its unlocking position to retain the plunger in the unlocking position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, of which: 
     FIG. 1 is a perspective view from the front of a lock in accordance with one embodiment of the invention, 
     FIG. 2 is a similar view from the rear, 
     FIG. 3 is a top view of the lock, 
     FIG. 4 is a longitudinal sectional view of the lock showing the plunger in the locking position, 
     FIG. 5 is a similar view showing the plunger in the unlocking position, 
     FIG. 6 is a perspective view of the plunger unit, with the housing portion being shown in phantom, 
     FIG. 7 is an exploded view of the lock showing the cover portion of the housing removed from the main portion thereof, 
     FIG. 8 is a similar view showing the various parts of the plunger unit, 
     FIG. 9 is a perspective view of the lock secured to a patio door which opens from right to left, 
     FIG. 10 is a similar view showing the lock with the mounting bracket reversed and secured to a patio door which opens from left to right, and 
     FIG. 11 is a perspective view of the lock secured to a vertically moveable window. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     Referring to the drawings, a lock  10  has a housing  12  and a plunger unit  14  mounted in the housing  12 . The plunger unit  14  has a sleeve  16 , a plunger  18  slidably mounted in the sleeve  16 , and helical spring  20  surrounding the plunger  18  within the sleeve  16  and acting between an annular shoulder  19  on the plunger  18  and an annular shoulder  21  on the sleeve  16 . The spring  20  resiliently biases the plunger  18  to a locking position in which a free end portion  22  of the plunger  18  projects from one end of the sleeve  16  as shown for example in FIGS. 1,  2  and  4 . 
     The plunger  18  also has a manually operable portion  24  projecting from the opposite end of the plunger  16 . The manually operable portion  24  and the free end portion  22  of the plunger  18  are separate parts secured together by screw-threaded engagement at  26 . Thus, the manually operable portion  24  and the free end portion  22  of the plunger  18  are separable to enable the spring  20  to be assembled with the plunger  18  and the sleeve  16 . 
     The plunger  18  also has an unlocking position in which the free end portion  22  thereof is withdrawn into the sleeve  16  by pulling the manually operable portion  24  against the action of the spring  20 . 
     The manually operable portion  24  of the plunger  18  and the sleeve  16  have shaped adjacent ends  28 ,  30  respectively which form stop means which are mutually engageable by rotation of the plunger  18  relative to the sleeve  16  when the plunger is in the unlocking position (shown in FIG. 6) to retain the plunger  18  in the unlocking position. 
     The housing  12  has a main portion  32  and a cover portion  34  removably secured thereto, the main portion  32  and the cover portion  34  having longitudinally extending recesses  36 ,  38  respectively using the plunger unit  14 . The main portion  32  and the cover portion  34  of the housing  12  also have pairs of inter-engaging longitudinally-extending keyways  40 ,  42  respectively on opposite sides to enable the cover portion  34  to be attached to and detached from the main portion  32  of the housing  12 . 
     One of the keyways  42  in the cover portion  34  has an enlarged end portion  43  which receives a peg  41  at the corresponding end of the keyway  40  in the main housing portion  32  to provide stop means limiting sliding movement of the cover portion  34  relative to the main portion  32  so that the cover portion  34  becomes correctly positioned relative to the main housing portion  32  by engagement of the peg  14  with the junction between the enlarged end  43  and the remainder of the keyway  42 . The sleeve  16  of the plunger unit  14  and the main housing portion  32  have inter-engaging means in the form of a small cylindrical peg  44  in the recess  36  of the main housing portion  32  and a longitudinally extending series of apertures  46  in the sleeve  16  to prevent movement of the sleeve  16  relative to the main housing portion  32 , see FIG.  8 . The plunger unit  14  is fitted into the recessed  36  in the main housing portion  32  by engaging the peg  44  into one of the apertures  46  in the sleeve  16 , the aperture  46  selected determining the amount by which the free end portion  22  of the plunger  18  projects from the housing  12 . 
     The rear face of the main housing portion  32  carries an L-shaped mounting bracket  50 , with one L-arm  52  secured by screws  53  to the rear face of the main housing portion  32  and another L-arm  54 . The L-arm  54  has circular apertures  56  on slots  58  to receive screws to enable the lock  10  to be secured to a member to be locked, as will be described in more detail shortly. The main portion  32  and the cover portion  34  of the housing  12  and the mounting bracket  50  may conveniently be aluminum extrusions. 
     FIG. 9 shows the lock  10  secured to a top corner of the frame  62  of a sliding patio door  64  which opens from left to right by screws  60  passing through the apertures  56  and/or slots  58  into the door frame  62 . The plunger  18  is in the locking position (see FIG.  4 ), and the free end portion  22  of the plunger  18  extends into a drilled aperture  25  in the upper track  23  of the door  64 . Thus, the door  64  cannot be opened by sliding movement, nor can it be lifted up out of its lower track (not shown). 
     The plunger  18  can be moved to the unlocking position (see FIG. 5) by simply pulling down on the plunger  18  by manually gripping the manually gripable portion  24 . The plunger  18  can be caused to remain in the unlocking position by turning the plunger  18  by 180° from the position shown in FIG. 5 to the position shown in FIG. 6 so that the plunger  18  is retained in the unlocking position by engagement of the end surface  28  of the plunger  18  of the end surface  30  of the sleeve  16 . 
     FIG. 10 shows the lock  10  fitted to a patio door  66  which opens from right to left. In this case, the L-arm  52  ( 50 ) is detached from main housing portion  32  by removing screws  53  (see FIG.  2 ), and reversing the bracket  50  to the position shown in FIG.  10  and replacing the screws  53  before fitting the lock  10  to the door  66 . 
     FIG. 11 shows the lock  10  fitted to atop corner of a vertically movable window  68 , with the free end portion  22  of the plunger  16  engaging in an aperture in a side member  72  of the window frame. 
     The lock  10  may also be fitted to a sliding or angularly movable cupboard door, with the free end portion  22  of the plunger  16  engaging in an aperture in an adjacent door frame member. 
     The advantages of the invention will now be readily apparent to a person skilled in the art. Other embodiments will also now be readily apparent, the scope of the invention being defined in the appended claims.