Patent Publication Number: US-6988749-B2

Title: Door locking system for motor vehicle

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a door locking system for a motor vehicle which locks and unlocks a door lock such as a trunk lid lock or a tailgate lock by motor power or manual power. 
   2. Description of the Prior Art 
   In a typical door locking system for car doors including a trunk lid and a tailgate, a striker is fixed to one of a car body and a car door, a base plate having a striker leading slot is fixed to the other of the car body and the car door, and a latch and a pawl for locking and unlocking the striker are pivoted on the base plate on opposite sides of the striker leading slot, respectively. 
   A typical door locking system is conventionally provided with a powered operation device and a manual operation device. The powered operation device is provided with a rotary pressing member which is driven by a motor to press the pawl so that it rotates in a lock releasing direction to disengage the latch so that the latch releases from the striker. The manual operation device is provided with an opening lever which is engaged with the pawl to rotate the pawl in the lock releasing direction by a manual operation. The opening lever is conventionally provided as a member independent of the rotary pressing member. This means that the rotary pressing member and the opening lever are respectively pivoted about different rotational shafts. This structure increases the number of elements and the size of the door locking system. Moreover, due to this structure, the direction in which load is applied to the rotational shaft of the pawl when the pawl is rotated by the rotary pressing member is different from the direction in which load is applied to the rotational shaft of the pawl when the pawl is rotated by the opening lever. This cannot ensure a smooth movement of the pawl because the pawl is pressed by the rotary pressing member and the opening lever from different directions. 
   In addition, in the conventional door locking system, since the rotary pressing member is supported by the base plate to be freely rotatable, it is necessary to provide the door locking system with an independent rotational shaft about which the rotary pressing member is freely rotatable. Providing such an independent rotational shaft causes a problem in the positioning accuracy between the independent rotational shaft and associated elements, an increase in the number of elements of the door locking system, and an increase in the number of man-hours for assembly. 
   Moreover, in typical power door locking systems, the rotary pressing member applies pressure to the pawl via a roller which is rotatably fixed to the pawl at a point thereon which comes into contact with the rotary pressing member when the rotary pressing member applies pressure to the pawl. Providing the pawl with such a roller that is provided as an element independent of the pawl causes a problem in the positioning accuracy between the pawl and the roller, increases the number of elements of the power door locking system, and increases the number of man-hours for assembly. 
   On the other hand, typical door locking systems are generally provided with a luggage compartment lamp switch which turns ON and OFF a luggage compartment lamp when a trunk lid lock or a tailgate lock is unlocked and locked, respectively. The luggage compartment lamp switch includes a stationary terminal strip serving as one of positive and negative electrodes of the luggage compartment lamp switch, and a movable terminal strip serving as the other of positive and negative electrodes of the luggage compartment lamp switch. The movable terminal strip is in contact with the stationary terminal strip when the locking system is in the lock release position in which the striker is disengaged from the latch, and the movable terminal strip is disengaged from the stationary terminal strip when the locking system is in the lock position in which the striker is engaged with the latch. 
   Conventionally, the structure providing electrical isolation between the stationary terminal strip and the movable terminal strip is complicated to prevent a malfunction from occurring, thus increasing the cost of production. 
   SUMMARY OF THE INVENTION 
   The present invention provides a door locking system for a motor vehicle which makes it possible to simplify the support structure for supporting a rotary pressing member with high positioning accuracy, and to reduce the number of elements of the door locking system and the number of man-hours for assembly. 
   The present invention provides a door locking system for a motor vehicle which makes it possible to simplify the support structure for supporting the opening lever which is operated when a door lock (e.g., a trunk lid lock or a tailgate lock) is manually unlocked. 
   The present invention provides a door locking system for a motor vehicle which makes it possible to simplify the mechanism around the pawl and to reduce the number of elements of the door locking system and the number of man-hours for assembly. 
   The present invention provides a door locking system for a motor vehicle which incorporates a luggage compartment lamp switch having a cost-reduced structure. 
   The present invention provides a door locking system for a motor vehicle which incorporates a luggage compartment lamp switch, wherein the door locking system includes a rotary pressing member which is driven by motor to press the pawl to unlock a door lock (e.g., a trunk lid lock or a tailgate lock), and wherein a power supply circuit and terminals thereof for supplying power to the motor and a switching circuit and terminal thereof for the luggage compartment lamp switch can be constructed easily in an efficient manner. 
   According to an aspect of the present invention, a door locking system for a motor vehicle is provided, including a striker fixed to one of a car body and a car door, a base plate fixed to the other of the car body and the car door, the base plate having a striker leading slot in which the striker is removably insertable, a latch for latching the striker, the latch being pivoted on the base plate on one of opposite sides of the striker leading slot, a pawl for locking and unlocking the latch, the pawl being pivoted on the base plate on the other of the opposite sides of the striker leading slot, a rotary pressing member driven by a motor to rotate the pawl in a lock release direction to disengage the latch so that the latch releases the striker, and a rotatable opening lever which is rotated by a manual operation to rotate the pawl in the lock release direction to disengage the latch. The rotary pressing member and the rotatable opening lever are pivoted about a common rotational shaft. 
   It is desirable for the door locking system to include a motor housing for housing the motor, the motor housing being made of synthetic resin mold. The rotational shaft is formed integral with the motor housing. The base plate includes a support portion which supports a tip of the rotational shaft to be supported by the base plate when the motor housing is fixed to the base plate. 
   The support portion of the base plate can include a support hole into which a tip of the rotational shaft is fitted. 
   The opening lever can be supported on the rotational shaft to be held between the base plate and the rotary pressing member. 
   The tip of the rotational shaft can include a small-diameter tip portion, and the opening lever can be supported on the rotational shaft to be held between the base plate and an annular stepped portion formed around the base of the small-diameter tip portion. 
   The support portion of the base plate can include a support boss into which a hole formed on the tip of the rotational shaft is fitted. It is desirable for the rotary pressing member and the rotatable opening lever to be rotatable relative to each other about the rotational shaft. 
   It is desirable for the rotary pressing member to come into contact with an engaging portion of the pawl to press the engaging portion when the rotary pressing member rotates the pawl in the lock release direction, the engaging portion being formed as a bent engaging portion. 
   The rotary pressing member can include a lock release cam, a cam surface of which is shaped so that a distance between the cam surface and an axis of rotation of the rotary pressing member increases gradually. 
   The bent engaging portion can include a linear portion which extends in a radial direction of the axis of rotation of the pawl, and an inclined portion which extends obliquely with respect to the linear portion from an end of the linear portion. The cam surface of the lock release cam first presses the inclined portion and subsequently presses the linear portion when the rotary pressing member rotates the pawl in the lock release direction to disengage the latch from the striker. 
   It is desirable for the rotary pressing member and the rotatable opening lever to be freely rotatable about the rotational shaft relative to each other. The rotatable opening lever comes into contact with the linear portion to press the linear portion when the rotatable opening lever rotates the pawl in the lock release direction. 
   It is desirable for the cam surface of the lock release cam to be shaped so that the distance between the cam surface and the axis of rotation of the rotary pressing member increases gradually in a rotational direction thereof. 
   The door locking system can include a luggage compartment lamp switch having a stationary terminal strip serving as a positive electrode and a movable terminal strip serving as a negative electrode. The movable terminal strip is in contact with the stationary terminal strip when the striker is disengaged from the latch. The movable terminal strip is disengaged from the stationary terminal strip when the striker is engaged with the latch. 
   The door locking system includes a motor housing for housing the motor, the motor housing being fixed to the base plate. One end of the movable terminal strip is fixed to the motor housing. 
   The door locking system can include a pair of terminal strips for supplying power to the motor. The pair of terminal strips and the stationary terminal strip are formed integral with the motor housing by insertion molding. One of the pair of terminal strips which serves as a negative electrode is electrically connected with the movable terminal strip. 
   It is desirable for the one end of the movable terminal strip and the one of the pair of terminal strips to be fixed to the base plate by a set screw which is also used to fix the motor housing to the base plate. 
   The motor housing can include a holding device for temporarily holding the movable terminal strip before the motor housing is fixed to the base plate. 
   It is desirable for the holding device to include a groove provided on the motor housing in which the one end of the movable terminal strip that is fixed to the motor housing is positioned, and two protrusions formed on the motor housing on opposite side surfaces of the groove to hold a portion of the movable terminal strip in the vicinity of the one end of the movable terminal strip between the two protrusions. 
   The car door can be a trunk lid or a tailgate. 
   It is desirable for the rotary pressing member to include a worm gear which is engaged with a worm gear of a worm on a rotary shaft of the motor. 
   The door locking system can include a biasing member for biasing the rotary pressing member in a rotational direction opposite to a rotational direction in which the rotary pressing member is driven by the motor. 
   The biasing member can be a torsion coil spring installed between the motor housing and the rotary pressing member around the rotational shaft. 
   It is desirable for the door locking system to include a spring for biasing the pawl and the latch to rotate in opposite rotational directions so as to engage with each other. 
   In another embodiment, a door locking system for a motor vehicle is provided, including a striker fixed to one of a car body and a car door, a base plate fixed to the other of the car body and the car door, the base plate having a striker leading slot in which the striker is removably insertable, a latch for latching the striker, the latch being pivoted on the base plate on one of opposite sides of the striker leading slot, a pawl for locking and unlocking the latch, the pawl being pivoted on the base plate on the other of the opposite sides of the striker leading slot, a motor which rotates a worm fixed to a rotary shaft of the motor, a cam-integrated worm wheel associated with the worm to be driven by the motor, wherein a lock release cam formed integral with the cam-integrated worm wheel presses the pawl to rotate the pawl in a lock release direction to disengage the latch so that the latch releases the striker when the cam-integrated worm wheel is driven by the motor, and a rotatable opening lever which is rotated by a manual operation to rotate the pawl in the lock release direction to disengage the latch so that the latch releases the striker. The cam-integrated worm wheel and the rotatable opening lever are pivoted about a common rotational shaft. 
   The present disclosure relates to subject matter contained in Japanese Patent Application Nos. 2001-386436 (filed on Dec. 19, 2001), 2001-386437 (filed on Dec. 19, 2001) and 2001-386438 (filed on Dec. 19, 2001) which are expressly incorporated herein by reference in their entireties. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be described below in detail with reference to the accompanying drawings, in which: 
       FIG. 1  is a front elevational view, partly developed, of an embodiment of a door locking system for a motor vehicle according to the present invention; 
       FIG. 2  is an exploded perspective view of the door locking system shown in  FIG. 1 ; 
       FIG. 3  is a longitudinal sectional view of the door locking system shown in  FIG. 1 ; 
       FIG. 4  is a rear elevational view of a motor housing of the door locking system shown in  FIG. 1 ; 
       FIG. 5  is a cross sectional view taken along the V—V line shown in  FIG. 4 ; 
       FIG. 6  is a rear elevational view of a cam-integrated worm wheel and a portion of the motor housing of the door locking system shown in  FIG. 1 ; 
       FIG. 7  is a cross sectional view taken along VII—VII line shown in  FIG. 6 ; 
       FIG. 8A  is a front elevational view of fundamental elements of the door locking system shown in  FIG. 1 , showing a locked state where a pawl is engaged with a latch and where the pawl is disengaged from a lock release cam of the cam-integrated worm wheel; 
       FIG. 8B  is a view similar to that of  FIG. 8A , showing a transitional state between the locked state shown in  FIG. 8A  and an unlocked state shown in  FIG. 8C ; 
       FIG. 8C  is a view similar to that of  FIG. 8A , showing an unlocked state where the pawl is rotated counterclockwise by a clockwise rotation of the lock release cam of the cam-integrated worm wheel to be disengaged from the latch; 
       FIG. 9  is a perspective view of a pair of terminal strips of a power supply circuit for supplying power to a motor unit and another pair of terminal strips of a switching circuit for supplying power to a luggage compartment lamp; 
       FIG. 10  shows an arrangement of the two pairs of terminal strips shown in  FIG. 9  in relation to the latch, showing the luggage compartment lamp switching circuit in a state where a luggage compartment lamp switch is OFF; 
       FIG. 11  is a view similar to that of  FIG. 10 , showing the luggage compartment lamp switching circuit in a state where the luggage compartment lamp switch is ON; 
       FIG. 12  is a cross sectional view taken along XII—XII line shown in  FIG. 10 ; 
       FIG. 13  is a view similar to that of  FIG. 7 , showing another embodiment of the structure supporting an opening lever of the door locking system shown in  FIG. 1 ; and 
       FIG. 14  is a view similar to a portion of  FIG. 2 , showing another embodiment of the structure supporting a rotational shaft on a base plate. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The general structure of an embodiment of a motor vehicle door locking system  11  according to the present invention will be discussed hereinafter. 
   The motor vehicle door locking system  11  serves as a trunk-lid locking system for locking the trunk lid of a motor vehicle. As shown in  FIGS. 1 and 2 , a base plate  12  made of conductive metal is fixed to one of the trunk lid and the car body of the trunk lid while a striker  13  is fixed to the other of the trunk lid and the car body of the trunk lid. For instance, in the present embodiment, the metal base plate  12  is fixed to the car body while the striker  13  is fixed to the trunk lid. The base plate  12  is provided with a striker leading slot  14 . The motor vehicle door locking system  11  is provided with a latch  17  and a pawl  18  which are pivoted on the metal base plate  12  at opposite sides of the striker leading slot  14 , respectively. 
   The latch  17  is provided with a striker holding groove  17   a , an engaging portion  17   b , a spring-engaging hole  17   c  and a switch lever pressing portion  17   d . The pawl  18  is provided with a locking portion  18   a  which is engageable with the engaging portion  17   b , a spring-engaging hook portion  18   b  and a driven arm portion  18   c . The pawl  18  is pivoted on a pivot pin  16  fixed to a support hole  12   f  (see  FIG. 2 ) formed on the base plate  12 , and the latch  17  is pivoted on a pivot pin  15  fixed to another support hole  12   g  (see  FIG. 2 ) formed on the base plate  12 . One end of an extension coil spring  19  is hooked through the spring-engaging hole  17   c  while the other end of the extension coil spring  19  is hooked over the spring-engaging hook portion  18   b  to bias the latch  17  and the pawl  18  to rotate in opposite rotational directions to make the engaging portion  17   b  and the locking portion  18   a  engage with each other. In a locked state shown in  FIG. 1  where the engaging portion  17   b  of the latch  17  is engaged with the locking portion  18   a  of the pawl  18 , the latch  17  is engaged with the striker  13  with the striker  13  held in the striker holding groove  17   a  and the striker leading slot  14 . In this locked state, disengaging the locking portion  18   a  of the pawl  18  from the engaging portion  17   b  of the latch  17  causes the latch  17  to rotate about the pivot pin  15  in a rotational direction (counterclockwise as viewed in  FIG. 1 ) by the spring force of the extension coil spring  19  to disengage the latch  17  from the striker  13  to thereby allow the striker  13  to move out of the striker leading slot  14  and the striker holding groove  17   a.    
   The motor vehicle door locking system  11  is provided with a motor housing  20  molded from synthetic resin which is fixed to the base plate  12 . As show in  FIG. 4 , the motor housing  20  is provided with a motor-unit accommodation recess  20   a , a rotary-member accommodation recess  20   b , and a rotational shaft  20   c  which projects from an inner surface of the rotary-member accommodation recess  20   b . The motor vehicle door locking system  11  is provided in the rotary-member accommodation recess  20   b  with a motor unit  21  which is fixed to an inner surface of the rotary-member accommodation recess  20   b . The motor unit  21  is provided with a worm  21   a  fixed onto a rotary shaft of the motor unit  21 . The rotational shaft  20   c  is provided at the tip thereof with a small-diameter tip portion  20   d  (see  FIGS. 2 ,  3  and  7 ) having a smaller diameter than the remaining part of the rotational shaft  20   c . The rotational shaft  20   c  extends to the base plate  12  so that the small-diameter tip portion  20   d  is fitted into a support hole  12   a  formed on the base plate  12 . 
   The base plate  12  is provided with three engaging holes: two engaging holes  12   b  and an engaging hole  12   b ′. The motor housing  20  is provided with two screw holes: a screw hole  20   f  and a screw hole  20   f ′ formed to correspond to corresponding one of the two engaging holes  12   b  (the left engaging hole  12   b  as viewed in  FIG. 1 ) and the engaging hole  12   b ′, respectively. The motor housing  20  is provided with a positioning protrusion  20   e  (see  FIG. 4 ) which is engaged in corresponding one of the two engaging holes  12   b  (the right engaging hole  12   b  as viewed in  FIG. 1 ). A set screw (not shown) is inserted in the left engaging hole  12   b  to be screwed into the screw hole  20   f , and another set screw  34  (see  FIG. 12 ) is inserted in the engaging hole  12   b ′ to be screwed into the screw hole  20   f ′. Two negative terminal strips  31  and  33  are fixed to the base plate  12  by the set screw  34  that is screwed into the screw hole  20   f ′ via the engaging hole  12   b′.    
   A plate portion of the base plate  12  which has the striker leading slot  14  is angled relatively to another plate portion of the base plate  12  to which the motor housing  20  is fixed; i.e., these two plate portions do not lie in a plane. Although each of the latch  17  and the pawl  18  has a bent portion to correspond to the shape of the base plate  12 , each of the latch  17  and the pawl  18  is illustrated as having no bent portion in the drawings for the purpose of illustration. 
   The motor vehicle door locking system  11  is provided on the rotational shaft  20   c  with a cam-integrated worm wheel (pawl pressing rotary member)  22  and an opening lever  23  so that the cam-integrated worm wheel  22  and the opening lever  23  can freely rotate about the rotational shaft  20   c  relative to each other. As shown in  FIGS. 6 and 7 , the cam-integrated worm wheel  22  is provided with an axial hole  22   a  in which the rotational shaft  20   c  of the motor housing  20  is rotatably fitted, a worm gear  22   b  which is engaged with a worm gear of the worm  21   a  of the motor unit  21 , and a lock release cam  22   c . The worm gear  22   b  and the lock release cam  22   c  are formed integral with each other. The lock release cam  22   c  has a cam surface which is shaped so that the distance between the cam surface and the axial hole  22   a  increases gradually in a counterclockwise direction as viewed in  FIG. 1  or a clockwise direction as viewed in  FIG. 4 . 
   The opening lever  23  is provided with a pivot hole  23   a  in which the rotational shaft  20   c  of the motor housing  20  is rotatably fitted, a lock release arm  23   b , a cable hooking arm  23   c  and a rod coupling arm  23   d . A tip of an opener cable  24 , which is drawn when an associated lock release manual lever (not shown) installed in the inside of the car is manually pulled, is fixed to the wire hooking arm  23   c . A lock rod (not shown), which is pulled when a key-operated trunk lid lock (not shown) is opened with a key, is coupled to the rod coupling arm  23   d.    
   Each of the lock release cam  22   c  of the cam-integrated worm wheel  22  and the lock release arm  23   b  of the opening lever  23  can be engaged with and disengaged from a bent engaging portion  18   d  which is formed at the tip (free end) of the driven arm portion  18   c  of the pawl  18 . The bent engaging portion  18   d  is composed of two parts: a linear portion  18   d   1  and an inclined portion  18   d   2 . The linear portion  18   d   1  is pressed by the lock release cam  22   c  of the cam-integrated worm wheel  22  or the lock release arm  23   b  of the opening lever  23 . The inclined portion  18   d   2  is pressed only by the lock release cam  22   c . The linear portion  18   d   1  is pressed by the lock release arm  23   b  in a direction to rotate the pawl  18  counterclockwise as viewed in  FIG. 1  if the opening lever  23  is pulled by the opener cable  24  via the wire hooking arm  23   c  or by the lock rod via the rod coupling arm  23   d  to rotate clockwise as viewed in  FIG. 1 . 
   The base plate  12  is provided with a bent portion  12   c  so that a compressed coil spring  25  is installed between the bent portion  12   c  and the wire hooking arm  23   c  of the opening lever  23 . The compressed coil spring  25  biases the opening lever  23  in a direction (returning direction) of moving the lock release arm  23   b  away from the driven arm portion  18   c  of the pawl  18 , i.e., counterclockwise as viewed in  FIG. 1 . The opening lever  23  abuts against a stop (not shown) when positioned at an initial position; namely, the stop determines the initial position of the opening lever  23 . A torsion coil spring  22   d  (see  FIGS. 6 and 7 ) is installed between the motor housing  20  and the cam-integrated worm wheel  22  around the axial hole  22   a  to bias the cam-integrated worm wheel  22  counterclockwise as viewed in  FIGS. 1 and 2 . The lock release cam  22   c  of the cam-integrated worm wheel  22  abuts against a stop wall  20   t  (see  FIG. 6 ) of the motor housing  20  when the cam-integrated worm wheel  22  fully rotates counterclockwise as viewed in  FIG. 6  to a rotational extremity of the cam-integrated worm wheel  22 . When the cam-integrated worm wheel  22  is in the rotational extremity as shown in  FIG. 6 , the lock release cam  22   c  of the cam-integrated worm wheel  22  is in a disengaged position thereof where the lock release cam  22   c  is disengaged from the bent engaging portion  18   d  of the pawl  18 . 
   If power is supplied to the motor unit  21  to rotate the worm gear  22   b  via the worm  21   a  clockwise as viewed in  FIGS. 1 ,  8 A,  8 B and  8 C in response to a signal (e.g., a lock-release wireless signal), the bent engaging portion  18   d  of the pawl  18  is pressed by the lock release cam  22   c , which is formed integral with the worm gear  22   b , in a direction to rotate the pawl  18  counterclockwise as viewed in  FIG. 1  (see  FIGS. 8A ,  8 B and  8 C). 
   If the pawl  18  rotates about the pivot pin  16  counterclockwise as viewed in  FIGS. 1 ,  8 A,  8 B and  8 C via rotation of either the cam-integrated worm wheel  22  or the opening lever  23 , the locking portion  18   a  of the pawl  18  is disengaged from the engaging portion  17   b  of the latch  17  to thereby allow the striker  13  to move out of the striker leading slot  14  and the striker holding groove  17   a.    
   As shown in  FIGS. 9 through 12 , the motor housing  20  is provided with a positive terminal strip  30 , a negative terminal strip  31  and a positive terminal strip (stationary terminal)  32 . The positive terminal strip  30  and the negative terminal strip  31  are used to supply power to the motor unit  21 . The positive terminal strip  32  is used to supply power to a luggage compartment lamp  35  (see  FIGS. 10 and 11 ) of the car. These three terminal strips  30 ,  31  and  32  are formed integral with the motor housing  20  by insertion molding. One end of the positive terminal strip  30  projects into the motor-unit accommodation recess  20   a  (see  FIGS. 4 and 12 ) to be formed as a motor-side positive contact  30   a  which is inserted into a positive contact slot  21   b  (see  FIG. 2 ) of the motor unit  21 , and the other end of the positive terminal strip  30  projects into the inside of a female connector portion  20   s  of the motor housing  20  to be formed as a positive connecting contact  30   b . The female connector portion  20   s  is formed integral with the motor housing  20 . A middle portion of the negative terminal strip  31  projects into the motor-unit accommodation recess  20   a  (see  FIGS. 4 and 12 ) to be formed as a motor-side negative contact  31   a  which is inserted into a negative contact slot  21   c  (see  FIG. 2 ) of the motor unit  21 , and one end of the negative terminal strip  31  projects into the inside of the female connector portion  20   s  of the motor housing  20  to be formed as a negative connecting contact  31   b . The negative terminal strip  31  is provided with an extension portion  31   c  for the luggage compartment lamp  35 . The extension portion  31   c  is provided at the tip thereof with a round terminal  31   d  having a circular hole which corresponds to the screw hole  20   f ′ of the motor housing  20 . The round terminal  31   d  is exposed to the outside of the motor housing  20  to be positioned on an outer surface of the motor housing  20  on the side of the base plate  12 . 
   The motor vehicle door locking system  11  is provided with a movable negative terminal strip (movable terminal)  33  which is used together with the positive terminal strip  32  to supply power to the luggage compartment lamp  35 . The positive terminal strip  32  and the movable negative terminal strip  33  constitute a leaf switch, wherein the movable negative terminal strip  33  serves as a semi-rigid leaf in which the major flexing occurs to contact with the positive terminal strip  32  when the switch is operated. One end of the movable negative terminal strip  33  is positioned between the base plate  12  at the engaging hole  12   b ′ and the motor housing  20  at the screw hole  20   f ′ to be fixed to the base plate  12  therebetween. More specifically, the movable negative terminal strip  33  is provided at one end thereof with a round terminal  33   a  having a circular hole which corresponds to the circular hole of the round terminal  31   d  of the negative terminal strip  31 , and is further provided with a resilient arm portion  33   b  which extends from the round terminal  33   a  toward the latch  17 . The round terminal  33   a  of the movable negative terminal strip  33  is positioned between the base plate  12  at the engaging hole  12   b ′ and the screw hole  20   f ′ of the motor housing  20 , and is fixed to the base plate  12  by a set screw  34  (see  FIG. 12 ) which is inserted in the engaging hole  12   b ′ to be screwed into the screw hole  20   f ′ with the round terminals  31   d  and  33   a  contacting each other. Accordingly, the negative terminal strip  31  and the movable negative terminal strip  33  are fixed to the base plate  12  to be grounded via the set screw  34  and the two round terminals  31   d  and  33   a . As shown in  FIG. 4 , a fixed end portion of the resilient arm portion  33   b  is positioned in a swing-movement limit groove  20   g  formed on the motor housing  20  while a free end portion of the resilient arm portion  33   b  is positioned outside the motor housing  20 . A portion of the movable negative terminal strip  33  in the vicinity of the round terminal  33   a  is held in between two protrusions  20   h  and  20   i  formed on the motor housing  20  on opposite side surfaces of the swing-movement limit groove  20   g  so that the portion of the movable negative terminal strip  33  in the vicinity of the round terminal  33   a  does not bend resiliently in the swing-movement limit groove  20   g . The swing-movement limit groove  20   g  and the two protrusions  20   h  and  20   i  constitute a holding device and are effectively used to temporarily hold the movable negative terminal strip  33  on the motor housing  20  before the motor housing  20  is fixed to the base plate  12 . 
   The resilient arm portion  33   b  of the movable negative terminal strip  33  extends toward the switch lever pressing portion  17   d  of the latch  17 . The latch  17  rotates about the pivot pin  15  clockwise and counterclockwise as viewed in  FIG. 1  when the trunk lid is locked and unlocked, respectively. When the latch  17  is in the lock position (the position shown in  FIG. 1 ), the switch lever pressing portion  17   d  of the latch  17  presses the resilient arm portion  33   b  of the movable negative terminal strip  33  rightwards as viewed in  FIG. 1  to resiliently bend the resilient arm portion  33   b  about the protrusion  20   i  in the same direction. In this state, the resilient arm portion  33   b  is not in contact with the positive terminal strip  32  as shown in  FIG. 1 . When the latch  17  is in the unlock position (the position shown in  FIG. 11 ), the switch lever pressing portion  17   d  of the latch  17  does not press against the resilient arm portion  33   b  of the movable negative terminal strip  33 , so that the resilient arm portion  33   b  is not resiliently bent. In this state, the resilient arm portion  33   b  is in contact with the positive terminal strip (stationary contact)  32  as shown in  FIG. 11 . 
   One end of the positive terminal strip  32  for the luggage compartment lamp  35 , which is formed integral with the motor housing  20  by insertion molding as described above, projects into the inside of the female connector portion  20   s  of the motor housing  20  to be formed as a positive connecting contact  32   a , and the other end of the positive terminal strip  32  is extended to a stationary position to serve as a stationary contact  32   b  with which the resilient arm portion  33   b  contacts when the switch lever pressing portion  17   d  of the latch  17  does not press against the resilient arm portion  33   b . Namely, the resilient arm portion  33   b  contacts with the stationary contact  32   b  when in a free state, i.e., when the latch  17  is in the unlock position (see  FIG. 11 ), and the resilient arm portion  33   b  resiliently bends to be disengaged from the stationary contact  32   b  when the latch  17  is in the lock position (see  FIG. 10 ). 
   A male connector (not shown) is plugged into the female connector portion  20   s  of the motor housing  20  to connect a power supply circuit (not shown) between the positive connecting contact  30   b  and the negative connecting contact  31   b  to supply power to the motor unit  21 . A luggage compartment lamp lighting circuit for lighting the luggage compartment lamp  35  is established between the negative connecting contact  31   b  and the positive connecting contact  32   a  (see  FIGS. 10 and 11 ). 
   In the motor vehicle door locking system  11  having the above described structure, in a locked state shown in  FIG. 1  where the engaging portion  17   b  of the latch  17  is engaged with the locking portion  18   a  of the pawl  18  while the striker  13  is held in the striker holding groove  17   a , a rotation of the opening lever  23  clockwise as viewed in  FIG. 1  by an operation of either the associated lock release manual lever via the cable hooking arm  23   c  or the key-operated trunk lid lock via the rod coupling arm  23   d , causes the lock release arm  23   b  of the opening lever  23  to press against the linear portion  18   d   1  of the pawl  18  in a direction to rotate the pawl  18  counterclockwise as viewed in  FIG. 1 . This causes the locking portion  18   a  to be disengaged from the engaging portion  17   b  of the latch  17 , which in turn causes the latch  17  to rotate about the pivot pin  15  counterclockwise as viewed in  FIG. 1  by the spring force of the extension coil spring  19  to disengage the latch  17  from the striker  13  to thereby allow the striker  13  to move out of the striker leading slot  14  and the striker holding groove  17   a . Once the opening lever  23  becomes free from a lock releasing force applied thereto, the opening lever  23  rotates counterclockwise as viewed in  FIG. 1  to return to the initial rotational position thereof by the spring force of the compression coil spring  25 . 
   Moreover, in a locked state shown in  FIG. 1 , if power is supplied to the motor unit  21  to rotate the worm  21   a  in response to a signal (e.g., a lock-release wireless signal), the worm wheel  22  rotates via the worm gear  22   b  clockwise as viewed in  FIGS. 1 ,  8 A,  8 B and  8 C against the spring force of the torsion coil spring  22   d , the inclined portion  18   d   2  of the bent engaging portion  18   d  of the pawl  18  is pressed by the lock release cam  22   c  in a direction to rotate the pawl  18  counterclockwise as viewed in  FIG. 1  to thereby allow the striker  13  to move out of the striker leading slot  14  and the striker holding groove  17   a , in a similar manner as in the case where either the associated lock release manual lever or the key-operated trunk lid lock is operated. 
   Furthermore, in a locked state shown in  FIG. 1 , wherein the striker  13  is held in the striker holding groove  17   a , the switch lever pressing portion  17   d  of the latch  17  presses against the resilient arm portion  33   b  of the movable negative terminal strip  33  for the luggage compartment lamp  35  so that the resilient arm portion  33   b  is disengaged from the stationary contact  32   b . Accordingly, in the state shown in  FIG. 1 , no power is supplied to the luggage compartment lamp  35  so that the luggage compartment lamp  35  is not turned ON. However, in an unlocked state shown in  FIG. 11 , wherein the striker  13  is allowed to move out of the striker leading slot  14  and the striker holding groove  17   a , the switch lever pressing portion  17   d  of the latch  17  is disengaged from the resilient arm portion  33   b  of the movable negative terminal strip  33  to free the resilient arm portion  33   b  from any external force. Accordingly, in the state shown in  FIG. 11 , the resilient arm portion  33   b  is in contact with the positive terminal strip  32  as shown in  FIG. 11  so that power is supplied to the luggage compartment lamp  35 . Consequently, the luggage compartment lamp  35  comes ON. 
   Features of the motor vehicle door locking system  11  will be discussed hereinafter. 
   In the above described embodiment of the motor vehicle door locking system, the rotational shaft  20   c  which supports the cam-integrated worm wheel  22  so as to freely rotate about the rotational shaft  20   c  is formed integral with the motor housing  20  that is molded from synthetic resin. Moreover, the opening lever  23  which is manually operated to disengage the pawl  18  from the latch  17  is supported by the rotational shaft  20   c  to be freely rotatable about the rotational shaft  20   c  relative to the cam-integrated worm wheel  22 . Furthermore, in a state where the cam-integrated worm wheel  22  and the opening lever  23  are fitted on the rotational shaft  20   c  to be freely rotatable about the rotational shaft  20   c , the motor housing  20  and the base plate  12  are fixed to each other by a set screw (not shown) which is inserted in corresponding one of the two engaging holes  12   b  to be screwed into the screw hole  20   f  and another set screw  34  which is inserted in the engaging hole  12   b ′ to be screwed into the screw hole  20   f ′ with the small-diameter tip portion  20   d  of the rotational shaft  20   c  and the positioning protrusion  20   e  being respectively fitted into the support hole  12   a  and the other engaging hole  12   b  of the base plate  12 . 
   This structure wherein the rotational shaft  20   c  is formed integral with the motor housing  20  makes it possible to reduce the number of elements of the motor vehicle door locking system  11  and also the number of man-hours for assembly, and further makes it possible to raise the positioning accuracy between the rotational shaft  20   c  and associated elements of the door locking system  11 . In addition, not only the supporting strength of the rotational shaft  20   c  but also the supporting strength of the motor housing  20  can be improved by the structure wherein the small-diameter tip portion  20   d  of the rotational shaft  20   c  is supported by the base plate  12  at the corresponding support hole  12   a . Accordingly, the motor housing  20  together with the rotational shaft  20   c  can obtain a sufficient supporting strength even if the number of the screw holes  20   f  and  20   f ′ and the number of the engaging holes  12   b  and  12   b ′ are small. 
   Regarding the supporting of the opening lever  23  that is fitted on the rotational shaft  20   c  to be freely rotatable about the rotational shaft  20   c , the following two embodiments are possible: a first embodiment shown in  FIG. 7  in which the opening lever  23  is supported on the rotational shaft  20   c  to be held between the base plate  12  and the cam-integrated worm wheel  22 , and a second embodiment shown in  FIG. 13  in which the opening lever  23  is supported on the rotational shaft  20   c  to be held between the base plate  12  and an annular stepped portion  20   d ′ formed around the base of the small-diameter tip portion  20   d . According to the first embodiment of supporting the opening lever  23 , a sufficient strength of the rotational shaft  20   c  can be easily obtained. According to the second embodiment of supporting the opening lever  23 , the opening lever  23  can be easily positioned in the right place in the axial direction. For instance, if the space between the annular stepped portion  20   d ′ and the base plate  12  is set to be substantially equal to the thickness of the opening lever  23 , axial play in the opening lever  23  is removed. 
     FIG. 14  shows an alternative embodiment for fitting the rotational shaft  20   c  of the motor housing  20  to the base plate  12 . In this embodiment, a boss  12   a ′ is provided on the base plate  12  instead of the support hole  12   a , and a hole  20   d ′ is provided in tip of the rotational shaft  20   c  instead of the small-diameter tip portion  20   d . In this alternative, either structure shown in  FIG. 7  or  FIG. 13  can be employed. Namely, like the structure shown in  FIG. 7 , the opening lever  23  can be supported on the rotational shaft to be held between the base plate  12  and the cam-integrated worm wheel  22 . Instead, like the structure shown in  FIG. 13 , an annular stepped portion ( 20   d ′) can be formed at a tip of the rotational shaft  20   c  and the opening lever  23  can be supported on the rotational shaft  20   c  to be held between the base plate  12  and the annular stepped portion  20   d′.    
   In the above described embodiment of the motor vehicle door locking system  11 , the opening lever  23 , which is used to be provided as a member independent of a cam-integrated worm wheel, and the cam-integrated worm wheel  22  are fitted coaxially on the rotational shaft  20   c  to be supported thereby. This structure makes it possible to reduce the number of elements of the motor vehicle door locking system  11  and also the number of man-hours for assembly. 
   The base plate  12  can also be used as a base plate used in a manual door locking system without using a motor such as the motor unit  21 . In this case where the base plate  12  is used in a manual door locking system for a motor vehicle, the base plate  12  can be modified so that all the elements thereof associated with the motor housing  20  are removed from the base plate  12  and that a rotational shaft corresponding to the rotational shaft  20   c  is implanted into the support hole  12   a  of the base plate  12 . A manually-operated opening lever and other members can be fitted on the implanted rotational shaft to be freely rotatable about the implanted rotational shaft relative to one another. 
   Although the cam-integrated worm wheel  22  serves as a rotary pressing member which presses the pawl  18  in the above described embodiment of the motor vehicle door locking system  11 , the shape and the structure of the lock release cam  22   c  of the cam-integrated worm wheel  22  can be modified as needed. Moreover, the mechanism for giving rotation to the rotary pressing member which presses the pawl  18  is not limited solely to the above described particular mechanism. 
   As can be understood from the foregoing, according to the present invention, since the rotational shaft  20   c  on which the rotary pressing member is formed integral with the motor housing, the support structure for supporting the rotary pressing member is simplified with a high positioning accuracy while the number of elements of the door locking system and the number of man-hours for assembly are reduced. 
   In addition, the support structure for supporting the opening lever  23  is simplified by the structure wherein the opening lever  23  and the rotary pressing member are rotatably supported by the common rotational shaft  20   c  formed integral with the motor housing. This structure also ensures a smooth movement of the pawl  18  because the direction in which load is applied to the rotational shaft of the pawl  18  when the pawl  18  is rotated by a rotation of the rotary pressing member is identical to the direction in which load is applied to the rotational shaft  20   c  of the pawl  18  when the pawl  18  is rotated by a rotation of the opening lever  23 . 
   In the above described embodiment of the motor vehicle door locking system  11 , the bent engaging portion  18   d  is formed at the free end of the driven arm portion  18   c  as described above. The linear portion  18   d   1  of the bent engaging portion  18   d  extends in a radial direction of the axis of rotation (the pivot pin  16 ) of the pawl  18 , while the inclined portion  18   d   2  of the bent engaging portion  18   d  extends obliquely from the tip of the linear portion  18   d   1 . The linear portion  18   d   1  and the inclined portion  18   d   2  are formed integral with each other to have a smooth engaging surface extending over the linear portion  18   d   1  and the inclined portion  18   d   2 . When the bent engaging portion  18   d  is pressed by the lock release cam  22   c , that has a cam surface which is shaped so that the distance between the cam surface and the axial hole  22   a  increases gradually, the inclined portion  18   d   2  is pressed firstly by the lock release cam  22   c  and the linear portion  18   d   1  is pressed secondly by the lock release cam  22   c . The lock release arm  23   b  of the opening lever  23  presses the linear portion  18   d   1 . 
   Due to this structure, it is no longer necessary for the motor vehicle door locking system  11  to be provided with any conventional roller to be fixed to the pawl  18  because the engaging portion of the pawl  18 , which comes into contact with the lock release cam  22   c  when the lock release cam  22   c  applies pressure to the pawl  18 , is provided as the bent engaging portion  18   d  formed integral with the pawl  18 . The positioning accuracy between the pawl  18  and the cam-integrated worm wheel  22  can be ensured by the positioning accuracy between the pivot pin  16 , which is fixed to the support hole  12   f  on the base plate  12 , and the rotational shaft  20   c , which is fixed to the support hole  12   a  on the base plate  12 . Since the pivot pin  16  and the rotational shaft  20   c  are fixed to the supporting holes  12   f  and  12   a  formed on a common plate, i.e. the base plate  12 , the positioning accuracy between the pawl  18  and the cam-integrated worm wheel  22  is easily ensured. 
   The number of elements of the door locking system and the number of man-hours for assembly are reduced by the above described structure wherein the opening lever  23  is rotatably fitted on the rotational shaft  20   c  on which the cam-integrated worm wheel  22  is rotatably fitted, and further wherein the engaging portion of the pawl  18  which comes into contact with the lock release cam  22   c  when the lock release cam  22   c  applies pressure to the pawl  18  is provided as the bent engaging portion  18   d  formed integral with the pawl  18 . 
   As can be understood from the foregoing, according to the present invention, the mechanism around the pawl  18  is simplified while the number of elements of the door locking system  11  and the number of man-hours for assembly are reduced because the engaging portion of the pawl  18  which comes into contact with the rotary pressing member is provided as a bent engaging portion ( 18   d ) formed integral with the pawl  18 . 
   In addition, the support structure for supporting the opening lever  23  is simplified by the structure wherein the engaging portion of the pawl  18  which comes into contact with the opening lever  23 , that is manually operated when the trunk lid is unlocked, is formed on a portion of the bent engaging portion  18   d  of the pawl  18 . 
   In the above described embodiment of the motor vehicle door locking system  11 , the positive terminal strip (stationary terminal)  32  and the movable negative terminal strip (movable terminal)  33  constitute one of positive and negative electrodes of the luggage compartment lamp switch and the other of positive and negative electrodes of the luggage compartment lamp switch, respectively. In addition, the movable negative terminal strip  33  is in contact with the stationary positive terminal strip  32  when the locking system  11  is in the lock release position in which the striker  13  is disengaged from the latch  17 , and the movable negative terminal strip  33  is disengaged from the stationary positive terminal strip  32  when the locking system  11  is in the lock release position in which the striker  13  is engaged with the latch  17 . In this structure, even if the movable negative terminal strip  33  contacts with peripheral conductive parts such as the base plate  12 , no electrical problem or breakdown occurs because the base plate  12  is originally grounded and the movable negative terminal strip  33  is a negative terminal. Therefore, each of the movable negative terminal strip  33  and peripheral members which may contact with the movable negative terminal strip  33  does not need to have an electrical isolation structure. This reduces the cost of production. 
   In the above described embodiment of the motor vehicle door locking system, the cam-integrated worm wheel  22  for performing a lock release operation is driven by motor, and the motor housing  20  for housing the motor unit  21  is fixed to the base plate  12 . In this structure, an end of the movable negative terminal strip  33 , i.e., the round terminal  33   a  is fixed to the motor housing  20 . This manner of fixing the movable negative terminal strip  33  to the motor housing  20  via one end of the movable negative terminal strip  33  simplifies the structure supporting the movable negative terminal strip  33 . 
   In addition, the positive and negative terminal strips  30  and  31  (a pair of terminals for supplying power to the motor unit  21 ) and the positive terminal strip  32  (a positive terminal for supplying power to the luggage compartment lamp  35 ) are formed integral with the motor housing  20  by insertion molding while the movable negative terminal strip  33  (a negative terminal for supplying power to the luggage compartment lamp  35 ) is electrically connected to the negative terminal strip  31  via the round terminal  31   d  thereof. This structure wherein the three terminal strips  30 ,  31  and  32  are formed integral with the motor housing  20  by insertion molding and wherein a part of the movable negative terminal strip  33  for supplying power to the luggage compartment lamp  35  is shared between the movable negative terminal strip  33  and the negative terminal strip  31  simplifies the wiring structure of the motor vehicle door locking system  11 . 
   Additionally, the round terminal  33   a  of the movable negative terminal strip  33  is fixed onto the round terminal  31   d  of the negative terminal strip  31  by the set screw  34  which is also used to fix the motor housing  20  onto the base plate  12 . Due to this structure, the motor housing  20  and the movable negative terminal strip  33  is fixed to the base plate  12  at a time of fixing the motor housing  20  to the base plate  12 . Furthermore, the movable negative terminal strip  33  can be easily fixed to the base plate  12  because a fixed end portion of the resilient arm portion  33   b  is positioned in the swing-movement limit groove  20   g  to be held in between the two protrusions  20   h  and  20   i  so as not to bend resiliently in the swing-movement limit groove  20   g  before the motor housing  20  is fixed to the base plate  12 . Accordingly, the movable negative terminal strip  33  can be temporality held in the swing-movement limit groove  20   g  by the two protrusions  20   h  and  20   i  before the motor housing  20  is fixed to the base plate  12 , which eases installation of the movable negative terminal strip  33 . 
   As can be understood from the foregoing, according to the present invention, a door locking system for a motor vehicle which incorporates a luggage compartment lamp switch having a cost-reduction structure can be achieved. Moreover, a power supply circuit and terminals thereof for supplying power to the motor and a switching circuit and terminal thereof for the luggage compartment lamp switch can be constructed easily in an efficient manner. 
   Although the motor vehicle door locking system is used as a door locking system for locking and unlocking the trunk lid of a car (e.g., a sedan) in the above descriptions, the present embodiment of the motor vehicle door locking system can also be used as a door locking system for locking and unlocking the tailgate of a car (e.g., a station wagon). 
   Obvious changes may be made in the specific embodiment of the present invention described herein, such modifications being within the spirit and scope of the invention claimed. It is indicated that all matter contained herein is illustrative and does not limit the scope of the present invention.