Patent GB-1080788-A (GB)
Title: Latch for motor car doors
IPC: E05B65/32
Filed: 1964-12-02
Abstract: 1,080,788. Latch fastenings. T. U. THOMSSEN. Dec. 2, 1964 [Dec. 2, 1963; May 13, 1964], No. 49103/64. Heading E2A. A latch for a motor vehicle door comprises a forked latch bolt 3 or 41 rotatably mounted by means of a spindle 4 or 40 in a latch plate 1 or 34 and engageable with a keeper pin 14 or 43 mounted on a keeper plate 15 or 42, means 5, 17 or 44, 56 for holding the bolt in its door latching position, a member 6 or 45 mounted on said latch bolt spindle for movement relatively thereto, coupling means 7 or 47 normally connecting said member with said latch bolt spindle for rotation therewith and compression spring means acting against said member, said member rotating with said latch bolt spindle during closing movement of said door whereby said spring means applies a force thereto assisting the rotational movement of said latch bolt to its door latching position. In the construction shown in Figs. 1 and 4 the latch plate 1 is L shaped and the latch bolt spindle is rotatably mounted in a bearing in one of its arms; the latch bolt 3 is positioned on one side of the latch plate arm and on the opposite side is a detent plate 5 also secured to the spindle 4. A spring is secured between the plate 5 and the latch plate arm to bias the plate 5 and hence the latch bolt to the unlatching position. The assembly of latch bolt spindle and detent plate is held in the latching position by a pawl 17 which engages a detent shoulder 19 on the plate 5. The pawl is pivoted to the latch plate and is biassed into engagement with the plate 5 by a spring; the pawl 17 is disengaged from the plate 5 from the outside of the door by an operator which engages a lug on the pawl and from the inside of the door via a bell crank lever 31 which engages the second on the pawl. The member 6 is freely mounted on the bolt spindle 4 and on its underface has a guide track 13 which is engaged by a roller 12 carried by a rod 10; the rod 10 is pivotally and slidably mounted on the plate 1 by means of a pin and slot connection and a spring 9 surrounds the rod and urges the roller into contact with the track 13, the rod roller and spring constituting the spring means. The pivot pin 11 of the roller passes through a slot in the plate 1 and has an extension 27 on the same side of the plate 1 as the latch bolt 3. The dispositions of the spindle 4, the roller pivot pin 11 and the pivot pin 16 for the rod 10 are such that in moving from one end of the slot in the latch plate to the other the pin 11 passes through a dead centre position. The means 7 for releasably coupling the detent plate 5 to the member 6 is a slidable plunger which is biassed by a spring 22; the plunger 7 is moved out of engagement with a shoulder on the plate 5 by a lever 20 which is pivoted to the plate 1 and coupled to the pawl 17; this lever engages a pin 21 connected to the slidable plunger 7. The keeper plate 15 carries a hook member 25 which is pivoted to the plate 15 by means of a pin 24; the hook member carries a pin 30 which is engageable with a slot in a plate 26 attached to one arm of the mounting plate 1 underneath the latch bolt. Figs. 1 and 4 show the position of the various parts of the latch when the door is closed; when the pawl 17 is pivoted out of engagement with the detent plate 5 from the inside or outside of the door the lever 20 through its engagement with the pin 21 moves the slidable plunger 7 from engagement with the detent plate 5 and simultaneously the pawl 17 is moved out of engagement with the shoulder 19 so that the latch bolt can pivot to free itself from the keeper pin 4. As the door is opened the end portion 23 of the hook member 25 moves the roller 11 along the slot in the latch plate 1 by engagement with the extension 27 of the pivot pin 11 and this moves the roller through the dead centre position and the spring 9 holds the roller at the other end of the slot in the latch plate. Since the member 6 is released from the latch bolt it pivots under its own weight anti-clockwise and the roller is moved along the slot until further movement is prevented by engagement with a slot 29 on the latch plate 1; in this position the plunger 7 re-engages the shoulder 8 on the detent plate 5 to couple the member 6 to the plate 5. The parts of the latch remain in this position during closing movement of the door until the latch bolt engages the keeper pin 14. When this engagement takes place further closing movement of the door pivots the latch bolt and because of the coupling between the member 6 and the plate 5 the member 6 is also pivoted clockwise and the end of its guide track 13 moves the roller 12 and rod 10 against the pressure of the spring 9 until the pivot pin passes dead centre; when this happens the roller 12 under the bias of the spring 9 aids the clockwise movement of the member 6 and hence through the engagement of the latch bolt with the keeper the closing movement of the door until the member 6 comes into engagement with a stop 28. In this position the pawl 17 under the urge of its spring moves into engagement with the shoudler 19 to hold the latch bolt in the latching position. In another construction Figs. 8 and 10 the latch plate 34 is also L shaped and carries on one arm a bearing 39 which supports the latch bolt spindle 40 which on one side of the mounting plate carries the forked latch bolt 41 and on the other side of the mounting plate arm a detent plate 44 both the bolt and plate being secured to the spindle 40. The spindle 40 also carries is a freely rotatable manner the member 45 which by means of a pivot pin 46 carries the coupling means 47 which is in the form of a lever the lever having a pin 48 which projects through a slot in the member 45 to engage a slot 51 in the detent plate 44 in a manner such that when the pin 48 is in a portion 50 of the slot 51 the detent plate and member 45 are coupled together. The member 45 has a projection 55 which is engaged by a lever 35 pivoted to the other arm of the latch plate. This lever is biassed by a spring 38 so that it tends to rotate clockwise and the rotation is normally prevented by a pivoted spring biassed catch member 53 one end of which protrudes through the latch plate into the path of an abutment 54 on the keeper plate 42 which carries the keeper pin 43 engageable with the latch bolt. The lever 35 is connected by means of a cable to the frame of the door on the hinged side of the door so that during opening movement of the door the spring 38 which constitutes the spring means is compressed. The detent plate 44 and hence the latch bolt are held in the latching position by a pivoted lever 56 which under the bias of a spring engages a shoulder on the detent plate; this lever has an extension which is engageable with the pin 48 of the lever 47 and by the member 45. Pivoting movement of the lever 56 from inside or outside of the door releases the detent plate so that the latch bolt can release the keeper pin 43 and also uncouple the plate 45 from the detent plate by lifting the lever 47 from engagement with the portion 50 of the slot 51; opening movement of the door then compresses spring 38 via the lever 35 and the cable connected to the door frame, until the catch 53 can engage the portion 52 of the lever 35 to hold the spring in the compressed condition; movement of the lever 35 also allows the pivoting of member 45 under the bias of a spring to enable the pin 48 of the lever 47 to become re-engaged with the portion 50 of the slot 51 in the detent plate 44. During closing movement of the door the parts remain in this condition until the latch bolt engages the pin 43 on the keeper plate 42 which pivots the latch bolt; shortly after this happens the abutment 54 on the keeper plate engages the catch 53 and pivots it out of engagement with the lever 35 which then pivots under the urge of the spring 38 and moves the latch bolt via the detent plate and member 45 which is coupled to the detent plate so that the spring urges the door to its closed position in which pivoting of the latch bolt enables the lever 56 to engage the shoulder of the detent plate to hold the latch bolt in the latching position.