Door latch device

Abstract

To prevent a door from opening unintentionally upon application of an impact force without inviting problems of responsiveness or equipment downsizing.SOLUTION: A door latch device with a latch unit 10 and a link lever 30, which includes: a weight 51 movably arranged in a housing 1 and maintained in a normal position by urging force of an urging spring 52; the urging spring 52 being normally maintained in the force accumulation state by engaging an engagement pawl 50a, and being configured to, on the other hand, when the force accumulation state is released, shift the link lever 30 from an unlocked state to a locked state and maintained in the resulting state; and an engaging arm 51a that disengages the engagement pawl 50a from the urging spring 52 when the weight 51 moves against the urging force of the urging spring 52 when the urging force of the urging spring 52 is in its force accumulation state.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a door latch device configured to prevent a door from being inadvertently opened even when an impact force such as a collision is applied to a vehicle.

Background Art

[0002] Some door latch devices configured to keep a door closed with respect to a vehicle are configured to prevent a situation where the door is inadvertently opened even when an impact force such as a collision is applied. For example, in Patent Document 1, an inertia lever is disposed to move between a block position and a retracted position with respect to a link lever that unlatches a latch unit. In this door latch device, when an impact force is applied, the inertia lever moves from the retracted position to the block position, causing the link lever to shift from an unlocked state to a locked state and maintaining that state, thereby preventing the door from being inadvertently opened.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, in a door latch device configured such that the movement of an inertia lever shifts a link lever from an unlocked state to a locked state, it is necessary to secure a large movement distance for the inertia lever. That is, in order not to affect the operation of the link lever at the retracted position, the inertia lever must be disposed at a position outside the operation region of the link lever. Therefore, when an impact force is applied, after moving the inertia lever to the operation region of the link lever, it is necessary to further move the inertia lever until the link lever is shifted from the unlocked state to the locked state, and the movement distance of the inertia lever has to be long. As a result, there are concerns such as a problem of responsiveness, for example, it takes a certain amount of time from when the impact force is applied until the link lever of the door latch device becomes locked, and a problem that it becomes difficult to reduce the size of the device.

[0005] In view of the above circumstances, an object of the present invention is to provide a door latch device capable of preventing a situation where the door is inadvertently opened when an impact force is applied without causing problems related to responsiveness and downsizing of the device.

Means for Solving the Problems

[0006] To achieve the above object, a door latch device according to the present invention is in a latched state when the door is closed with respect to the vehicle body, restricting movement of the door in the opening direction with respect to the vehicle body, while allowing movement of the door in the opening direction with respect to the vehicle body when in an unlatched state. The door latch device includes a latch unit and a link lever. The link lever is provided on the device body in a manner that allows it to shift between an unlocked state and a locked state. In the unlocked state, when the door is operated to open, the link lever shifts the latch unit to the unlatched state. In the locked state, when the door is operated to open, the link lever maintains the latch unit in the latched state. The door latch device is characterized by comprising a weight movably disposed on the device body and maintained in a normal position by the biasing force of a weight biasing member, a biasing member that is normally maintained in a charged state and biases the link lever to shift from the unlocked state to the locked state and maintain that state when the charged state is released, and a charge release mechanism that releases the charged state of the biasing member when the weight moves against the biasing force of the weight biasing member in a state where the biasing member is charged.

[0007] Further, in the present invention, in the above-described door latch device, the link lever is rotatably and slidably disposed with respect to the device body. By rotating, it switches between the unlocked state and the locked state, and by sliding in the unlocked state, it can shift the latch unit to the unlatched state. The device body is provided with an engaging claw that maintains the biasing member in the charged state. The charge release mechanism has an engaging arm portion provided on the weight, which, when the weight moves against the biasing force of the weight biasing member, engages with the biasing member to release the engaged state with the engaging claw.

[0008] Further, the present invention is the above-described door latch device, wherein the link lever has an engagement guide surface that deflects a biasing member whose engagement state with the engagement claw is released when sliding in the locked state and moves the link lever to engage with the engagement claw, and a spring force of an unlock spring that biases the link lever toward the unlocked state acts on the link lever.

[0009] Further, the present invention is the above-described door latch device, wherein the biasing member is a torsion coil spring that is engaged with the engagement claw via one arm portion and presses the link lever via the arm portion when the engagement state with the engagement claw is released, and an engagement return portion is provided in the device main body to guide the arm portion to engage with the engagement claw when the biasing member is deflected by the link lever.

[0010] Further, the present invention is the above-described door latch device, wherein the biasing member also has a function of maintaining the weight body in the normal position.

[0011] Further, the present invention is the above-described door latch device, wherein the biasing member is a torsion coil spring having a coil portion wound in a spiral shape and two arm portions extending radially from both ends of the coil portion, the weight body is maintained in the normal position by an axial spring force that contracts the coil portion, and the link lever is rotated toward the locked state by a torsional spring force via the two arm portions.

Advantages of the Invention

[0012] According to the present invention, when the hammer moves against the biasing force of the hammer biasing member due to an impact force, the energy storage state of the biasing member is released by the energy storage release mechanism, and the link lever shifts from the unlocked state to the locked state and maintains that state, thereby preventing the door from being accidentally opened. Moreover, the above-described operation only needs to release the energy storage state of the biasing member, and can be instantaneously performed without requiring a member that moves within the range from the unlocked state to the locked state of the link lever. As a result, not only is it advantageous in terms of responsiveness after the impact force is applied, but it is also advantageous for miniaturization because there is no need to secure a large space inside the door latch device.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0014] Hereinafter, a preferred embodiment of the door latch device according to the present invention will be described in detail with reference to the accompanying drawings. FIGS. 1 to 5 show a door latch device which is an embodiment of the present invention. The door latch device exemplified here is mounted on the side door of the front hinge arranged on the right side of a four-wheel vehicle, although not shown in the figures, and changes the engagement state with a striker provided on the vehicle body according to an opening operation by a door handle or a lock / unlock operation by a key, thereby controlling the opening and closing of the side door. Hereinafter, the detailed configuration of the door latch device will be described. For convenience, the directions of the respective components will be specified in the state of being mounted on the vehicle. In this door latch device, a latch unit 10 and a lock unit 20 are provided inside a housing 1 which is the device main body.

[0015] The latch unit 10 is configured to include a latch 12 rotatably disposed via a latch shaft 11 and a ratchet 14 rotatably disposed via a ratchet shaft 13. The latch shaft 11 and the ratchet shaft 13 extend substantially horizontally along the front and rear of any vehicle. In the illustrated example, the latch shaft 11 is provided in a portion above the vehicle with respect to the striker entry groove 2 provided in the housing 1, and the ratchet shaft 13 is provided in a portion inward of the vehicle with respect to the latch shaft 11 in a portion below the vehicle with respect to the striker entry groove 2. With respect to the striker entry groove 2, a striker (not shown) enters relatively from the inner side of the vehicle by closing the side door.

[0016] The latch 12 has a striker contact portion 12a and a hook portion 12b, and is biased in the unlatch direction (clockwise in FIG. 3) by the spring force of a latch spring (not shown) and is arranged in an unlatch state. The unlatch state means a state in which the hook portion 12b retracts upward with respect to the striker entry groove 2 while the striker contact portion 12a is arranged on the inner side (outer side) of the striker entry groove 2. When the side door is closed in the unlatch state, the striker entering the striker entry groove 2 contacts the striker contact portion 12a, so that the latch 12 rotates counterclockwise in FIG. 3 against the spring force of the latch spring, and the hook portion 12b is arranged in a state of crossing the opening end of the striker entry groove 2.

[0017] The ratchet 14 prevents the latch 12 from rotating in the unlatch direction by engaging with the hook portion 12b when the hook portion 12b of the latch 12 is arranged to cross the striker entry groove 2. This ratchet 14 is biased in the direction of engaging with the latch 12 (counterclockwise in FIG. 3) by the spring force of a ratchet spring (not shown). Therefore, when the striker enters the striker entry groove 2 and the hook portion 12b of the latch 12 is arranged to cross the striker entry groove 2, the ratchet 14 engages with the hook portion 12b (latch state) by the spring force of the ratchet spring, and that state is maintained.

[0018] The ratchet 14 is integrally provided with a ratchet lever 14a. The ratchet lever 14a extends from a portion of the ratchet 14 located inward of the ratchet shaft 13 toward the front side of the vehicle. When the ratchet lever 14a is moved upward against the spring force of the ratchet spring, the ratchet 14 rotates clockwise in FIG. 3, so that the engagement state with the latch 12 can be released. The latch 12 whose engagement state with the ratchet 14 is released returns to the unlatched state again by the spring force of a latch spring (not shown).

[0019] A link lever 30 is disposed at a portion below the ratchet lever 14a inside the housing 1. The link lever 30 has a support engagement hole 31 at one end and an engagement groove 32 along the longitudinal direction at the other end, and is movable up and down by the operations of the outside handle lever 41 and the inside handle lever 42, and can rotate about an axis in the left - right direction of the vehicle by the operation of the lock unit 20 and change between the unlocked state and the locked state. It is disposed in the housing 1. In the drawing, dots are applied to the link lever 30 to clarify its shape.

[0020] The outside handle lever 41 is rotatably disposed at a portion below the ratchet shaft 13 by an outside lever shaft 41a extending along the front and rear of the vehicle. Although not shown in the figure, an outside door handle of the side door is linked to an end portion of the outside handle lever 41 located on the outer side of the vehicle via an operating force transmission member such as a rod or a cable. An end portion 41b of the outside handle lever 41 located on the inner side of the vehicle engages with a support engagement hole 31 of the link lever 30 and is only capable of relative rotation. When the outside door handle is operated to open, the outside handle lever 41 rotates clockwise in FIG. 3 via the operating force transmission member, and the link lever 30 moves upward via the end portion 41b. When the opening operation of the outside door handle is stopped, the outside handle lever 41 rotates counterclockwise by the spring force of a return spring (not shown), and the link lever 30 moves downward to return to its normal position.

[0021] The inside handle lever 42 is rotatably disposed at a portion below the link lever 30 by an inside lever shaft 42a extending along the left and right of the vehicle, and a front end portion 42b located on the front side thereof faces the lower end surface of the link lever 30. Although not shown in the figure, the lower end portion of the inside handle lever 42 is linked to an inside door handle of the side door via an inside cable 43. When the inside door handle is operated to open, the inside handle lever 42 rotates clockwise in FIG. 4 via the inside cable 43, and the link lever 30 moves upward via the front end portion 42b of the inside handle lever 42. When the opening operation of the inside door handle is stopped, the inside handle lever 42 rotates counterclockwise by the spring force of a return spring (not shown), and the link lever 30 moves downward to return to its normal position.

[0022] The lock unit 20 includes a lock lever 22 and a sub-lock lever 23 that rotate around the axis of a lock shaft 21 along the left and right sides of the vehicle. The lock lever 22 and the sub-lock lever 23 can rotate relative to each other around the axis of the lock shaft 21 within the range of an arcuate guide groove 22a provided in the lock lever 22. An unlocking spring 24 is provided between the lock lever 22 and the sub-lock lever 23 to urge the sub-lock lever 23 to rotate clockwise in FIG. 4 with respect to the lock lever 22. The sub-lock lever 23 is linked to a link lever 30 by engaging a protrusion 23a with an engagement groove 32.

[0023] An electric motor 25 and a lock cable 26 are connected to the lock lever 22. The electric motor 25 performs a locking operation and an unlocking operation by operating a remote control owned by the vehicle user. The locking operation and the unlocking operation of the electric motor 25 are transmitted to the lock lever 22 via a worm gear 27 and a worm wheel 28. Although not shown in the figure, the lock cable 26 is operated for locking and unlocking by operating a lock knob provided on the side door, and is directly connected to the lock lever 22. In this lock unit 20, when the electric motor 25 or the lock cable 26 is operated for unlocking, the link lever 30 rotates clockwise in FIG. 4 via the lock lever 22 and the sub-lock lever 23, and becomes a substantially upright unlocked state. On the contrary, when the electric motor 25 or the lock cable 26 is operated for locking, the link lever 30 rotates counterclockwise via the lock lever 22 and the sub-lock lever 23, and becomes a locked state in which the upper end portion is inclined forward as shown in FIG. 5.

[0024] In addition, as shown in FIGS. 7 to 11, a weight body 51 and a biasing spring (biasing member: weight body biasing member) 52 are provided inside a case (device main body) 50 attached to a housing 1 in the door latch device. The weight body 51 is disposed at a position outside the link lever 30, behind the outside handle lever 41, and below the ratchet 14, and is disposed so as to be movable only along the left-right direction with respect to the case 50.

[0025] The biasing spring 52 is a torsion coil spring having arm portions 52b and 52c at both ends of a spirally wound coil portion 52a, and the coil portion 52a is disposed at a portion below the weight body 51 in the case 50 in a state along the left-right direction. As the biasing spring 52, one having a spring force larger than that of the unlocking spring 24 is applied. That is, when the link lever 30 in the unlocked state is pressed toward the locked state, the biasing spring 52 is configured to shift the link lever 30 to the locked state against the spring force of the unlocking spring 24 and maintain that state. The arm portion located on the outer side in the biasing spring 52 (hereinafter referred to as the outer arm portion 52b when distinguishing) is locked to the weight body 51. The weight body 51 locked to the outer arm portion 52b is maintained at a normal position on the inner side with respect to the case 50 by the spring force (axial spring force by which the coil portion 52a contracts) of the biasing spring 52. The arm portion located on the inner side in the biasing spring 52 (hereinafter referred to as the inner arm portion 52c when distinguishing) protrudes above the upper end of the case 50 by extending upward from the coil portion 52a, and further, the upper end thereof is bent inward at substantially a right angle to form a pressing contact portion 52d. This inner arm portion 52c is detachably engaged with an engaging claw 50a provided on the case 50.

[0026] The engaging claw 50a is formed at the front end of the wall portion located on the inner side of the case 50 and protrudes outward from the surface facing outward. As shown in FIG. 8, the engaging claw 50a is provided with a locking surface 50b at a portion located on the rear side and an engaging guide surface 50c at a portion located on the front side. The locking surface 50b extends substantially orthogonally to the front-rear direction, and can maintain the urging spring 52 in a state of being bent in the twisting direction when the inner arm portion 52c is engaged, and can maintain the state in which the pressing contact portion 52d is separated from the link lever 30 arranged in the unlocked state. When the inner arm portion 52c deviates from the locking surface 50b, the inner arm portion 52c moves forward by the spring force in the twisting direction of the urging spring 52, and the pressing contact portion 52d presses the link lever 30 from the rear side, so that the link lever 30 in the unlocked state can be switched to the locked state. The engaging guide surface 50c extends so as to be inclined to gradually move inward toward the front. The engaging guide surface 50c is configured to be arranged to face the inner arm portion 52c on the rear side of the inner arm portion 52c when the inner arm portion 52c of the urging spring 52 deviates from the locking surface 50b and the pressing contact portion 52d is in contact with the link lever 30.

[0027] Furthermore, the door latch device is provided with an engaging arm portion 51a on the weight body 51 and an engaging return portion 33 on the link lever 30. The engaging arm portion 51a extends forward from the front portion of the portion located on the inner side of the weight body 51. The engaging arm portion 51a is arranged on the inner side of the inner arm portion 52c in a state where the inner arm portion 52c of the urging spring 52 is engaged with the locking surface 50b of the case 50, and can move the inner arm portion 52c outward when the weight body 51 moves outward with respect to the case 50.

[0028] The engagement return part 33 is provided at the edge located on the rear side of the link lever 30, and protrudes so as to gradually incline rearward downward even when the link lever 30 is in the locked state. This engagement return part 33 is located below the pressing contact part 52d that has deviated from the locking surface 50b when the link lever 30 is disposed downward in the locked state, and can come into contact with the pressing contact part 52d when the link lever 30 moves upward from this state. When the link lever 30 moves upward with the pressing contact part 52d in contact, the pressing contact part 52d will be gradually moved to the rear side by the inclination action of the engagement return part 33.

[0029] In the door latch device configured as described above, when the inner arm part 52c is engaged with the locking surface 50b, the biasing spring 52 is bent in the twisting direction and maintained in that state, and the pressing contact part 52d is maintained in a state separated from the link lever 30. Therefore, when the electric motor 25 or the lock cable 26 is in the unlocked operation state, as shown in FIG. 4, since the link lever 30 is disposed in the unlocked state, if the outside door handle or the inside door handle is operated to open, the latch unit 10 will be in the unlatched state and the side door can be opened.

[0030] When the electric motor 25 or the lock cable 26 is operated to lock, as shown in FIG. 5, the link lever 30 is in the locked state with a forward inclination via the lock lever 22 and the sub-lock lever 23. Therefore, even when the link lever 30 rises, it will not contact the ratchet lever 14a. Therefore, even if the outside door handle or the inside door handle is operated to open, the ratchet 14 remains engaged with the latch 12, and the side door is maintained in a closed state with respect to the vehicle body.

[0031] On the one hand, in the above-described door latch device, when an impact force is applied to the vehicle body in the unlocked state and the weight body 51 once moves outward against the spring force of the biasing spring 52 (the axial spring force by which the coil portion 52a contracts), the engaging arm portion 51a moves outward together with the weight body 51. Therefore, due to the outward movement of the weight body 51, the inner arm portion 52c also moves outward via the engaging arm portion 51a, and eventually the engagement state between the inner arm portion 52c of the biasing spring 52 and the locking surface 50b is released. As a result, as shown in FIG. 6, the pressing contact portion 52d of the biasing spring 52 comes into contact with the link lever 30, and the link lever 30 is switched to the locked state and maintained in the locked state by the torsional spring force of the biasing spring 52. Therefore, from this state, there is no concern that the side door will be inadvertently opened even if the outside door handle or the inside door handle is operated to open.

[0032] Moreover, for the above-described operation, it is only necessary for the weight body 51 to move as long as the inner arm portion 52c of the biasing spring 52 releases the engagement state with the locking surface 50b of the engagement claw 50a. After that, the link lever 30 is instantaneously shifted from the unlocked state to the locked state by the spring force in the torsional direction of the biasing spring 52, and there is no need for a separate member that moves within the range from the unlocked state to the locked state of the link lever 30. As a result, not only is it advantageous in terms of responsiveness from when the impact force is applied until the link lever 30 shifts to the locked state, but it is also advantageous for miniaturization because there is no need to secure a large space inside the door latch device. In particular, in the door latch device of the present embodiment, the link lever 30 is pressed by the spring force in the torsional direction of the biasing spring 52, and the weight body 51 is maintained in the normal position by the spring force in the axial direction in which the coil portion 52a contracts. That is, a single biasing spring 52 is made to serve two functions: a function of maintaining the state of the weight body and a function of shifting the link lever 30 to the locked state. For this reason, the number of parts can be reduced, and further miniaturization of the device becomes possible. In addition, since the mechanism for moving the weight body 51 by the impact force (in the embodiment, the mechanism for moving the weight body 51 toward the inner side of the vehicle) and the mechanism for shifting the link lever 30 from the unlocked state to the locked state (in the embodiment, the mechanism for shifting it toward the front side of the vehicle) are independent, there is also an advantage that the work for adjusting each of them becomes easy.

[0033] Here, as is clear from the figure, when the link lever 30 shifts to the locked state by the spring force of the biasing spring 52 in the unlocked state, the lock lever 22 does not rotate, and the sub-lock lever 23 only rotates with respect to the lock lever 22 against the spring force of the unlock spring 24. Further, the weight body 51 that has moved outward due to the impact force immediately returns to the normal position by the spring force of the biasing spring 52. Therefore, after an impact force is applied to the vehicle body, if the outside door handle or the inside door handle is operated to open, as shown in FIG. 10(b), the link lever 30 moves upward while remaining in the locked state, so that the engagement return portion 33 comes into contact with the pressing contact portion 52d, and the inner arm portion 52c moves rearward by its tilting action. The inner arm portion 52c that moves rearward is gradually guided outward by coming into contact with the engagement guide surface 50c of the engagement claw 50a. For this reason, as the rearward movement of the inner arm portion 52c progresses and it passes through the locking surface 50b, the inner arm portion 52c immediately moves inward by the spring force of the biasing spring 52 and returns to the state of being in contact with the locking surface 50b. As a result, the link lever 30 separated from the pressing contact portion 52d of the biasing spring 52 shifts to the unlocked state via the sub-lock lever 23 by the spring force of the unlock spring 24, and that state is maintained. That is, according to the door latch device described above, although it is possible to prevent the side door from accidentally opening when an impact force is applied, when the outside door handle or the inside door handle is operated to open, the link lever 30 comes into contact with the ratchet lever 14a with the second and subsequent opening operations, and the side door can be opened.

[0034] In addition, in the above-described embodiment, the door latch device mounted on the side door of a four-wheel vehicle is illustrated, but the present invention is not limited to this, and it can also be applied to a door latch device that controls the opening and closing of other doors of other vehicles. In this case, the door latch device does not necessarily have to be disposed on the door, and it may be disposed on the vehicle body.

[0035] In addition, in the above-described embodiment, the link lever 30 is pressed by the biasing spring 52 and the weight body 51 is maintained in the normal position. However, it is also possible to configure the member that presses the link lever 30 and the member that maintains the weight body 51 in the normal position with separate members. Note that the biasing member and the weight body biasing member do not necessarily have to be torsion coil springs.

[0036] Furthermore, in the above-described embodiment, the engaging claw 50a is provided on the case 50 attached to the housing 1 which is the apparatus main body. However, an engaging claw may be directly provided on the apparatus main body, or it is also possible to configure to provide an engaging claw on the weight body.

Explanation of Reference Numerals

[0037] 1 Housing 10 Latch Unit 20 Lock Unit 30 Link Lever 33 Engaging Return Portion 50 Case 50a Engaging Claw 50b Locking Surface 50c Engaging Guide Surface 51 Weight Body 51a Engaging Arm Portion 52 Biasing Spring 52a Coil Portion 52b Outer Arm Portion 52c Inner Arm Portion 52d Pressing Contact Portion

Claims

1. A latch unit that becomes latched when the door is closed with respect to the vehicle body, restricting movement of the door in the opening direction with respect to the vehicle body, and allowing movement of the door in the opening direction with respect to the vehicle body when in the unlatched state, A link lever provided on the apparatus main body in a manner that shifts between an unlocked state and a locked state, and in the unlocked state, when the door is opened, causing the latch unit to shift to the unlatched state, and in the locked state, when the door is opened, maintaining the latch unit in the latched state A door latch device comprising: A weight body movably disposed on the apparatus main body and maintained at a normal position by the biasing force of a weight biasing member, A biasing member that is normally maintained in a power storage state, and when the power storage state is released, biases the link lever to shift from the unlocked state to the locked state and maintain that state, A power storage release mechanism that releases the power storage state of the biasing member when the weight body moves against the biasing force of the weight biasing member in a state where the biasing member is in a power storage state Comprising: The link lever is rotatably and slidably disposed with respect to the apparatus main body, switches between an unlocked state and a locked state by rotating, and can shift the latch unit to the unlatched state by sliding in the unlocked state. The biasing member is deflected in a power storage state and rotates the link lever toward the locked state when the power storage state is released. The apparatus main body is provided with an engaging claw that maintains the biasing member in a power storage state. The power storage release mechanism is provided on the weight body and has an engaging arm portion that engages with the biasing member when moving against the biasing force of the weight biasing member, thereby releasing the engaging state with the engaging claw. A door latch device characterized by this.

2. The link lever has an engaging return portion that deflects a biasing member whose engaging state with the engaging claw is released when sliding in the locked state and moves it to engage with the engaging claw. The door latch device according to claim 1, characterized in that a spring force of an unlock spring that biases the link lever toward the unlocked state acts on the link lever.

3. The biasing member is a torsion coil spring that is engaged with the engaging claw via one arm portion and presses the link lever via the arm portion when the engagement state with the engaging claw is released. The door latch device according to claim 2, wherein the apparatus main body is provided with an engagement guide surface for guiding the arm portion to engage with the engaging claw when the biasing member is deflected by the link lever.

4. A latch unit that is in a latched state when the door is closed with respect to the vehicle body and restricts movement of the door in the opening direction with respect to the vehicle body, and allows movement of the door in the opening direction with respect to the vehicle body when in an unlatched state. A link lever provided in the apparatus main body in a manner that shifts between an unlocked state and a locked state, and in the unlocked state, shifts the latch unit to the unlatched state when the door is opened, and in the locked state, maintains the latch unit in the latched state even when the door is opened. A door latch device comprising: A weight body movably disposed on the apparatus main body and maintained in a normal position by the biasing force of a weight biasing member. A biasing member that is maintained in a charged state in a normal state, and biases the link lever to shift from the unlocked state to the locked state and maintain that state when the charged state is released. A charge release mechanism that releases the charged state of the biasing member when the weight body moves against the biasing force of the weight biasing member in a state where the biasing member is charged. Comprising: The biasing member also serves the function of maintaining the weight body in the normal position. The biasing member is a torsion coil spring having a coil portion wound in a spiral shape and two arm portions extending radially from both ends of the coil portion. The weight body is maintained in the normal position by the axial spring force that causes the coil portion to contract, and the link lever is rotated toward the locked state by the torsional spring force via the two arm portions. The door latch device is characterized by this.

Images