Wheelchair parking brake mechanism and wheelchair

Abstract

To provide a parking brake mechanism for a wheelchair that reduces the burden on the toes and shoes of a caregiver and enables the parking brake to be locked and released more safely and easily. [Solution] A parking brake mechanism for a wheelchair, comprising: a cam lever for actuating the brake shoes of a drum brake; a first arm connected at one end to the cam lever via a link mechanism and supported so as to be rotatable; and a second arm that abuts the first arm when the first arm is fixed; when the other end of the first arm is pushed down, the first arm rotates, causing the cam lever to operate and the drum brake to operate, and the first arm is fixed in an over-center state due to the fulcrum arrangement of the link mechanism; and when the second arm is pushed down in this fixed state, the first arm rotates in the opposite direction and the fixed state is released.

Description

[Technical Field]

[0001] The present disclosure relates to a parking brake mechanism for a wheelchair and a wheelchair. [Background technology]

[0002] Patent Document 1 describes a wheelchair that includes "a seat on which a person being assisted can sit, a frame with a handle formed on the back of the seat that can be gripped by the caregiver, a pair of wheels arranged on both the left and right sides of the frame, and a brake device that is attached to the axle of at least one of the pair of wheels and brakes the wheel, wherein the brake device has a running brake that applies a braking force to the wheel to be braked when traveling, and a parking brake that prevents the wheel from turning when parked, and the running brake mechanism of the running brake and the parking brake mechanism of the parking brake are connected and integrated by a connection mechanism arranged across each end of the parking brake mechanism and the running brake mechanism, and a position adjustment spring is provided in the connection mechanism." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-177376 Summary of the Invention [Problem to be solved by the invention]

[0004] In the wheelchair described in Patent Document 1, the running brake mechanism and the parking brake mechanism are integrated, and the parking brake is provided with a locking mechanism. The locking mechanism is activated by stepping on the pedal, so the caregiver can easily lock the drive wheels.

[0005] However, to release the lock, it was necessary to move the pedal in the opposite direction, i.e., to push up (kick up) the pedal. Pushing up (kicking up) the pedal usually requires lifting the pedal with the top of the foot. In nursing care settings, shoes with soft upper leather are sometimes used as indoor footwear, but in such cases, the action of kicking up the pedal places a strain on the toes of the caregiver. Furthermore, when shoes with sufficiently hard upper leather are used, there is a risk that the upper leather will be damaged or stained. The present disclosure solves at least one of the problems of the above-mentioned conventional technologies. [Means for solving the problem]

[0006] The first wheelchair parking brake mechanism of the present disclosure is a parking brake mechanism for a wheelchair equipped with drive wheels, and comprises: a cam lever for actuating the brake shoes of a drum brake; a first arm connected at one end to the cam lever via a link mechanism and supported so as to be rotatable; and a second arm that abuts the first arm when the first arm is fixed; when the other end of the first arm is pushed down, the first arm rotates, causing the cam lever to operate and the drum brake to operate, and the first arm is fixed in an over-center state due to the fulcrum arrangement of the link mechanism; and when the second arm is pushed down in the fixed state, the first arm rotates in the opposite direction, and the fixed state is released. [Effects of the Invention]

[0007] The wheelchair parking brake mechanism of the present disclosure can solve at least one of the problems of the prior art. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of an embodiment of a wheelchair as seen from the rear. [Figure 2] FIG. 2 is a left side view (cutaway end view) of a drive wheel of the wheelchair. [Figure 3]FIG. 2 is a rear view of the main parts of the wheelchair. [Figure 4] FIG. 2 is a schematic diagram of a drum brake shared by the brake mechanism. [Figure 5] FIG. 2 is a left side view of the parking brake mechanism, showing the state in which the brake is not applied. [Figure 6] FIG. 2 is a left side view of the parking brake mechanism, showing the brake in operation. [Figure 7] FIG. 2 is a plan view of the parking brake mechanism. [Figure 8] FIG. 2 is an explanatory diagram showing a center lock state of the parking brake mechanism (state before locking). [Figure 9] FIG. 2 is an explanatory diagram showing a center lock state of the parking brake mechanism (state after locking). [Figure 10] FIG. 2 is an explanatory diagram showing a center lock state of the parking brake mechanism (state immediately before unlocking). [Figure 11] FIG. 10 is a side view of another embodiment of the parking brake mechanism, showing the brake in an unactuated state. [Figure 12] FIG. 10 is a side view of another embodiment of the parking brake mechanism, showing the brake in operation. DETAILED DESCRIPTION OF THE INVENTION

[0009] The first wheelchair parking brake mechanism of the present disclosure is a parking brake mechanism for a wheelchair equipped with drive wheels, and comprises: a cam lever for actuating the brake shoes of a drum brake; a first arm connected at one end to the cam lever via a link mechanism and supported so as to be rotatable; and a second arm that abuts the first arm when the first arm is fixed; when the other end of the first arm is pushed down, the first arm rotates, causing the cam lever to operate and the drum brake to operate, and the first arm is fixed in an over-center state due to the fulcrum arrangement of the link mechanism; and when the second arm is pushed down in the fixed state, the first arm rotates in the opposite direction, and the fixed state is released.

[0010] According to the first wheelchair parking brake mechanism, the first arm can be locked by simply pushing down the other end of the first arm, making it over-center, and the brake can be locked. On the other hand, to release the locked state, the lock can be released by simply pushing down the second arm. In other words, both to lock and release the brake, it is sufficient to simply push down the first and second arms. This eliminates the need to kick the pedal in the opposite direction, as was previously required. This reduces the strain on the caregiver's toes and shoes, and makes it safer and easier to lock and release the parking brake.

[0011] The second wheelchair parking brake mechanism of the present disclosure is a wheelchair parking brake mechanism in which the link mechanism in the first wheelchair parking brake mechanism is provided with an elastic member and is configured so that when the fixed state is released, the first arm returns to the state it was in before being pressed down.

[0012] According to the second wheelchair parking brake mechanism, when the locked state is released, the elastic member provided in the link mechanism automatically returns the first arm to the state before it was pressed down. This eliminates the need to manually return the first arm after releasing the locked state, improving operability. Also, because the first arm always returns to its original position, the brake can be reliably locked the next time the wheelchair is used, further improving safety and convenience. Furthermore, the action of the elastic member prevents the arm from stopping in an incomplete position, improving the reliability of the entire mechanism.

[0013] A third wheelchair parking brake mechanism of the present disclosure is a wheelchair parking brake mechanism configured in the second wheelchair parking brake mechanism such that the over-center position is determined by the second arm abutting against the first arm.

[0014] According to the third wheelchair parking brake mechanism, the second arm abuts against the first arm, thereby determining the over-center position, and thus positioning the first arm in the locked state can be performed reliably and stably. This configuration ensures that the locked state is not disturbed, the parking brake is reliably maintained locked, and the release operation can be performed smoothly. Furthermore, by utilizing the abutment of the second arm, a complex positioning structure is not required, and a simple and reliable mechanism can be realized. Furthermore, this configuration allows for the entire mechanism to be made smaller and lighter, contributing to improved operability of the entire wheelchair.

[0015] A fourth wheelchair parking brake mechanism of the present disclosure is a wheelchair parking brake mechanism according to the third wheelchair parking brake mechanism, wherein the one end of the first arm has a hook-shaped structure and is configured to determine the over-center position by engaging with the second arm.

[0016] According to the fourth wheelchair parking brake mechanism, one end of the first arm has a hook-shaped structure, and by engaging with the second arm, the over-center position is determined, allowing for even greater precision in positioning the locked state. This configuration improves the stability of the locked state and further enhances the reliability of the brake. In addition, the hook-shaped engagement also functions as a stopper for positioning, preventing accidental release or misalignment. Furthermore, the use of an interlocking structure optimizes the contact area between parts, contributing to improved durability and long-term reliability. As a result, the safety and operability of the parking brake mechanism as a whole are greatly improved.

[0017] The fifth wheelchair parking brake mechanism of the present disclosure is a wheelchair parking brake mechanism configured in the fourth wheelchair parking brake mechanism such that when the second arm is pushed down, an elastic force is stored in the second elastic member, and the elastic force returns the second arm to the state it was in before being pushed down.

[0018] According to the fifth wheelchair parking brake mechanism, when the second arm is pushed down, an elastic force is stored in the second elastic member, and when the pushing-down operation is completed, the elastic force automatically returns the second arm to its original state. This configuration eliminates the need to manually return the second arm to its original position, simplifying the return operation after a release operation. Furthermore, by reliably returning the second arm to its original position, the next release operation can be performed smoothly, improving the operability and reliability of the entire parking brake mechanism. Furthermore, because the second elastic member assists the return operation, it is possible to prevent unexpected displacement of parts or snagging during operation, contributing to improved safety overall.

[0019] A sixth wheelchair parking brake mechanism of the present disclosure is the fifth wheelchair parking brake mechanism, wherein the second arm is crank-shaped in a plan view, and overlaps with the first arm in a plan view at the fulcrum end on the side that abuts the first arm, and a storage portion is provided in the first arm to store the fulcrum end so that the fulcrum end and the first arm do not interfere with each other before being pressed down.

[0020] According to the sixth wheelchair parking brake mechanism, the second arm has a crank shape in plan view, which provides a portion that overlaps with the first arm and a portion that is offset, improving the design flexibility of the entire mechanism. Furthermore, while the fulcrum end overlaps with the first arm, before being pressed down, it fits into a storage portion provided in the first arm, preventing interference between the fulcrum end and the first arm and enabling smooth operation. This configuration improves the operability of the parking brake and stabilizes the operation of the entire mechanism. Furthermore, the provision of the storage portion accurately maintains the relative positional relationship between the first arm and the second arm, ensuring reliable locking and release operations, further improving the reliability of the parking brake mechanism.

[0021] The seventh wheelchair parking brake mechanism of the present disclosure is a wheelchair parking brake mechanism of the sixth wheelchair parking brake mechanism, wherein the fulcrum end is configured to function as a stopper that determines the stopping position of the first arm during the return movement of the first arm.

[0022] According to the seventh wheelchair parking brake mechanism, the fulcrum end functions as a stopper that determines the stopping position of the first arm during its return movement, ensuring that the first arm stops at the appropriate position. This configuration prevents the first arm from rotating excessively during its return movement, improving the stability of the entire parking brake mechanism. Furthermore, by accurately determining the stopping position, the first arm can start operation from the appropriate initial position the next time it is operated, improving the consistency and reliability of operation. Furthermore, the stopper function reduces unnecessary load on the first arm and related components, contributing to improved durability and long-term reliability of the mechanism.

[0023] An eighth wheelchair parking brake mechanism of the present disclosure is the third parking brake mechanism, wherein the link mechanism includes a double-arm link member rotatably supported on the vehicle body, the double-arm link member includes arms extending in two different directions from a rotation center, the cam lever is connected to one of the arms, and the first arm is connected to the other arm via a link connector, and in the fixed state, the rotation fulcrum of the first arm, the first connection fulcrum between the link connector and the first arm, and the second connection fulcrum between the link connector and the double-arm link member are arranged over-center with respect to the first connection fulcrum.

[0024] The link mechanism provided in the parking brake mechanism of the eighth wheelchair includes a double-arm link member. This double-arm link member has arms extending in two directions from a rotation center. A cam lever is connected to one arm, and a first arm is connected to the other arm via a link connector (part of the link mechanism). This configuration can reduce the amount of movement (depression) of the first arm required to lock the wheelchair into place, further reducing the burden on the user.

[0025] A first wheelchair of the present disclosure is a wheelchair in which the parking brake mechanism of the wheelchair described in any one of the first to eighth aspects is attached to a drive wheel.

[0026] According to the first wheelchair, the parking brake can be locked and released easily and reliably. In particular, there is no need to kick the pedal in the opposite direction when releasing the brake, which reduces the burden on the caregiver during operation. In addition, the over-center mechanism stabilizes the locking and releasing of the brake, improving safety and operability. Furthermore, by incorporating a compact and highly reliable structure into the wheelchair, the ease of use and durability of the entire wheelchair are improved, making it possible to provide a wheelchair that is highly convenient for caregivers and users.

[0027] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The specification exemplifies specific materials and methods for embodying the technical idea of ​​the disclosure. The technical idea of ​​the disclosure is not limited to the following specific examples. Various modifications can be made to the technical idea of ​​the disclosure within the scope of the matters described in the claims. In particular, it should be noted that the drawings are schematic and may differ from the actual product.

[0028] (First Example) An embodiment of a wheelchair according to the present disclosure will be described below with reference to the drawings. Fig. 1 is a perspective view of an embodiment of a wheelchair 10 as seen from the rear. Fig. 2 is a left side view of a drive wheel 37 of the wheelchair 10. Fig. 2 is a cut-away end view, showing the axle 40 cut at the axial middle. Fig. 3 is a rear view of the wheelchair 10, showing only the main parts.

[0029] The wheelchair 10 has a foldable structure and can be stored in the trunk of a vehicle, etc. However, the wheelchair 10 is not necessarily limited to a foldable type. For clarity of the drawings, hand rims and brake devices for the user are not shown.

[0030] The rear of the wheelchair 10 is provided with a grip 22 that allows the user to operate the wheelchair 10. The grip 22 forms the upper and rear ends of the frame 20 of the wheelchair 10. The frame 20 also includes an upper frame 20a, a vertical frame 20b, and a lower frame 20c. The frame 20, which is made up of these components, forms a pair of symmetrical left and right frame sections 24 and 25. Furthermore, an armrest 21 is formed in the middle of the upper frame 20a in the front-to-rear direction on which the user can rest their arms. The frame 20 is made of hollow aluminum pipes to reduce weight.

[0031] The seat members 27, 28, one end of which is fixed to the left frame portion 24 and the right frame portion 25, respectively, include round bar members 27a, 28a, which intersect at their longitudinal midpoints. Axle members 31 are provided at the intersection 30, connecting the left frame portion 24 and the right frame portion 25 via these members. The other ends of the round bar members 27a, 28a are connected by connecting members 27b, 28b in the front-to-rear direction of the wheelchair 10, forming a member for attaching a cover member 43. The cover member 43 forms a seat surface on which a user can sit (see Figure 3). By rotating the round bar members 27a, 28a around the axle members 31, the left frame portion 24 and the right frame portion 25 move toward or away from each other, allowing the wheelchair 10 to be folded or unfolded.

[0032] Vertical members 33 extending downward are provided at the lower front ends of the left and right frame portions 24 and 25, and casters 35 are attached to these vertical members 33. The casters 35 are rotatable around a vertical axis and are also free to rotate along the ground. In addition, foldable treads (steps) 45 for users to place their feet on are provided near the positions where the casters 35 are attached.

[0033] Drive wheels 37 are attached to the outside of the lower rear portions of the left and right frame portions 24 and 25. The drive wheels 37 are mainly composed of wheels 37B and tires 37A attached thereto, and although the drawings show the wheels without hand rims, they may also be configured with hand rims. Furthermore, the handles 22 provided at the upper rear ends of the left and right frame portions 24 and 25 are provided with brake levers 102 that form part of a travel brake mechanism 110, which will be described later.

[0034] Covering members 41, 42, 43 are provided on the side, back, and bottom surfaces of the left and right frame sections 24, 25 to encase the user. Of these, the covering member 41 on the side surfaces is made of a hard, lightweight wooden, aluminum, or plastic plate so that it does not deform when the wheelchair 10 is folded. On the other hand, the covering members 42, 43 on the back and bottom surfaces are made of a flexible cloth material that can accommodate the changes in shape that occur when the wheelchair 10 is folded.

[0035] Next, the brake mechanism 100 provided in the wheelchair 10 will be described with reference to Figure 2 and Figures 4 to 10. The brake mechanism 100 is intended for use by a caregiver. The brake mechanism 100 is composed of two brake mechanisms with different uses. One is a running brake mechanism 110, and the other is a parking brake mechanism 120. These share a single drum brake 200 attached to the axle 40. In terms of function, the former is primarily used for temporary braking during travel, and the latter is used for parking. Figure 2 illustrates the running brake mechanism 110, the parking brake mechanism 120, and the drum brake 200 shared by them.

[0036] Fig. 4 is a schematic diagram of the drum brake 200 shared by the brake mechanism 100. Fig. 5 is a left side view of the parking brake mechanism 120, showing a state in which the brake is not applied, and Fig. 6 is a left side view of the parking brake mechanism 120, showing a state in which the brake is applied. Fig. 7 is a plan view of the parking brake mechanism 120. Figs. 8 to 10 are explanatory diagrams showing the center-lock state of the parking brake mechanism 120. Fig. 8 shows the state before locking, Fig. 9 shows the state after locking (locked state), and Fig. 10 shows the state immediately before the locked state is released by the action of the second arm 311.

[0037] The drum brake 200 is attached to the axle 40 (axle portion) of the drive wheel 37. As shown in Figure 4, the drum brake 200 has a pair of split brake shoes 210, 210 housed inside (on the inner periphery) of a drum (casing) 212 formed in a cup shape (cylindrical shape), the pair of brake shoes 210, 210 having one end connected by an anchor pin 214. A lining 216 is provided on the inner surface of the drum 212, and the pair of brake shoes 210, 210 face the inner surface of this lining 216.

[0038] A gap is provided in the circumferential direction of the drum 212 at the end (opposite end) of the brake shoe 210 opposite the connecting end (anchor pin 214), and an actuation cam 220 is disposed in this gap. The actuation cam 220 is rotatably fixed to the drum 212 by a support shaft 218. The actuation cam 220 has a shape, such as an ellipse, whose radial length varies depending on the angular position. The actuation cam 220 rotates together with the support shaft 218, thereby changing the gap between the pair of brake shoes 210, 210. This allows the brake shoe 210 to move closer to or farther away from the lining 216. In other words, the actuation cam 220 positions the brake shoe 210 so that it can approach and retract from the inner periphery of the drum 212.

[0039] When the brake shoe 210 is brought close enough to come into contact with the lining 216, friction occurs between the brake shoe 210 and the lining 216, and depending on the degree of contact, the rotational speed of the drum 212, which rotates together with the drive wheel 37, can be reduced or stopped. Furthermore, when the brake shoe 210 is moved away from the lining 216, the brake is released. Multiple springs 222 are connected between the pair of brake shoes 210, 210. These springs 222 are configured to store elastic force when the brake shoe 210 approaches the lining 216 (when the brake is activated). Therefore, conversely, when the brake is released, the stored elastic force acts to promote brake release.

[0040] The support shaft 218 protrudes through the side surface of the drum 212. A cam lever 240 is attached to this protruding portion. Therefore, the actuating cam 220 rotates in synchronization with the cam lever 240. Two brake mechanisms are connected to the cam lever 240 (FIG. 2). Specifically, a wire 132 of the running brake mechanism 110 and a link mechanism 142 of the parking brake mechanism 120 are connected to the cam lever 240. The wire 132 is composed of a wire 138 housed in a sheath 133. The sheath 133 is positioned on a fixed plate 224 extending radially from the drum brake 200 by a fixed portion 134. The wire 138 is connected to the brake lever 102 and expands and contracts in conjunction with the opening and closing of the brake lever 102. A return spring 136 is attached between the fixed portion 134 and the cam lever 240. According to the running brake mechanism 110 configured in this manner, the cam lever 240 rotates in conjunction with the opening and closing of the brake lever 102, thereby changing the operating state of the drum brake 200. The running brake mechanism 110 has a configuration similar to that of a rear wheel brake for a household bicycle.

[0041] Next, the parking brake mechanism 120 will be described with reference to Figures 5 to 10. The parking brake mechanism 120 shares the drum brake 200 with the running brake mechanism 110. The parking brake mechanism 120 is obtained by removing this shared portion.

[0042] The parking brake mechanism 120 is mainly composed of a link mechanism 142 and a first arm 310. The link mechanism 142 is configured as a so-called telescopic link rod, and includes a link rod 148, a first pivot joint 143, a second pivot joint 144, and a position adjustment spring 145. One end of the link rod 148 is connected to the cam lever 240 via the first pivot joint 143. Since the link rod 148 is fixed by the first pivot joint 143, the one end of the link rod 148 is rotatable with respect to the cam lever 240. Meanwhile, the other end of the link rod 148 passes through a through hole provided in the second pivot joint 144 fixed to the tip of the first arm 310.

[0043] The second pivot joint 144 is rotatably fixed to the first arm 310. The link rod 148 simply passes through the second pivot joint 144 but is not fixed thereto. That is, the link rod 148 is slidable (advances and retreats) while passing through the second pivot joint 144. With this configuration, when the first arm 310 rotates around a fulcrum 149, which is a fixed point to the mounting plate 152, the second pivot joint 144 moves toward or away from the first pivot joint 143. Furthermore, a position adjustment spring 145 is fixed between the first pivot joint 143 and the second pivot joint 144. The position adjustment spring 145 expands and contracts in response to the advancement and retreat of the link rod 148, and its elastic force pushes up or pulls back the cam lever 240. The position adjustment spring 145 functions to link operation of the first arm 310 with operation of the brake. Meanwhile, link rod 148 follows the movement of position adjustment spring 145 and each pivot joint, and plays a role in ensuring smooth and stable movement of link mechanism 142. With this structure, the elastic force of position adjustment spring 145 corresponding to the operation of first arm 310 is efficiently transmitted to cam lever 240. First arm 310 is connected to cam lever 240 via link mechanism 142, thereby realizing activation and release of drum brake 200.

[0044] The first arm 310 is L-shaped as a whole in a side view. The second pivot joint 144 of the link mechanism 142 is rotatably fixed to one end of the first arm 310. The foot pedal 302 is disposed at the other end of the first arm 310. Furthermore, a fulcrum 149 is disposed at a midpoint of the first arm 310. The first arm 310 is configured to be rotatable clockwise and counterclockwise around this fulcrum 149. The position of the fulcrum 149 is closer to the second pivot joint 144. This is to more efficiently transmit the force from the foot pedal 302 to the link mechanism 142 and the drum brake 200.

[0045] When the caregiver activates the parking brake mechanism 120, the foot pedal 302 is pressed down in the direction of the arrow in Figure 5. This causes the first arm 310 to rotate about the fulcrum 149, pushing up the second pivot joint 144 as shown in Figure 6. As a result, the cam lever 240 is lifted and the drum brake 200 is activated. When the first arm 310 is further rotated beyond a certain point, the first arm 310 becomes over-center and enters a fixed state (locked state). This fixed state means that the activated drum brake 200 is maintained in that state, and this is the basic mechanism of the parking brake mechanism 120.

[0046] The fixed state of the first arm 310 due to the over-center position will be described using Figures 8 to 10. Figure 8 shows the normal state before the first arm 310 is pushed down, and is a schematic diagram of the parking brake mechanism 120 when the wheelchair 10 is moving. In this state, the fulcrum 147, which is the intersection of a first line 400 connecting the fulcrum 146 of the first pivot joint 143 and the fulcrum 147 of the second pivot joint 144, and a second line 401 connecting the fulcrum 147 of the second pivot joint 144 and the fulcrum 149 of the first arm 310, is in a position that is convex downward (convex downward along the Z axis). At this time, the elastic force of the position adjustment spring 145 rotates the first arm 310 counterclockwise around the fulcrum 149, in a direction that returns it to its normal state (a direction that maintains the returned state), or, as shown in Figure 8, the position adjustment spring 145 is fully extended and no elastic force is exerted between the first pivot joint 143 and the second pivot joint 144.

[0047] In FIG. 9, fulcrum 147, which is the intersection of first line 400 and second line 401, has moved to a position that is convex upward (convex upward in the Z-axis direction). In this state, the elastic force of position adjustment spring 145 acts in a direction that rotates first arm 310 clockwise around fulcrum 149, thereby maintaining first arm 310 in a locked state. Also, in this state, second arm 311 abuts against first arm 310. The tip of first arm 310 is configured in a hook shape, which is configured to fit into the tip of second arm 311, and as a result, the over-center position is determined by second arm 311. In other words, the abutment of second arm 311 determines the limit of the amount of rotation of first arm 310 when over-center. In the fixed state, the fulcrum arrangement of fulcrum 146 of first pivot joint 143, fulcrum 147 of second pivot joint 144, and fulcrum 149 which is the center of rotation of first arm 310 is over-centered around fulcrum 147, and first arm 310 is locked.

[0048] In FIG. 10 , when foot pedal 303 of second arm 311 is pressed down, second arm 311 rotates clockwise around fulcrum 150, which pushes first arm 310, which was in contact in the locked state, causing it to rotate counterclockwise. At this time, first line 400 and second line 401 are aligned, which is the "center" state. In other words, fulcrum 146, fulcrum 147, and fulcrum 149 are aligned on a straight line. If the intersection (fulcrum 147) becomes convex upward beyond this "center," the elastic force of position adjustment spring 145 acts in a direction that maintains first arm 310 in a fixed state (locked). On the other hand, if the intersection becomes convex downward beyond the "center," the elastic force of position adjustment spring 145 acts in a direction that returns first arm 310 to its normal state. In the case of FIG. 10, a counterclockwise moment acts on first arm 310 by second arm 311, causing it to go beyond the "center" state and return to the normal state.

[0049] When second arm 311 is pushed down, second spring 151 connecting second arm 311 and mounting plate 152 expands and stores elastic force. Then, when second arm 311 is released, second spring 151 returns second arm 311 to the state it was in before it was pushed down. At this time, first arm 310 rotates counterclockwise around fulcrum 149 due to second arm 311 being pushed down, and is returned to the state it was in before it was pushed down by position adjustment spring 145. Therefore, when second arm 311 is pushed down and then released, first arm 310 and second arm 311 each return to the state they were in before they were pushed down (normal state).

[0050] As shown in FIG. 7 , second arm 311 has a crank shape in plan view, and overlaps first arm 310 at the end (fulcrum end) on the fulcrum 150 side that abuts against first arm 310 in the locked state. That is, first flat surface 311A, which is closer to the fulcrum end than step 311B, is positioned to overlap first arm 310 and is configured to abut against first arm 310 when first arm 310 is pressed down. On the other hand, second flat surface 311C, which is closer to the anti-fulcrum end than step 311B, does not overlap first arm 310. That is, second flat surface 311C is shifted to the left (Y-axis side) of the page in FIG. 7 from first arm 310 by the length of step 311B. This allows foot pedals 302, 303 to be provided at the ends of first arm 310 and second arm 311, respectively, to operate independently without interfering with each other.

[0051] On the other hand, as described above, on the fulcrum end side, the stepped portion 311B and the first flat portion 311A ​​are positioned to overlap with the first arm 310 in a plan view. In the locked state, the tip of the first flat portion 311A ​​and the first arm 310 must abut against each other as a stopper that determines the degree of rotation of the center lock and as a release mechanism that applies a rotational force to release the center lock. However, it is preferable that they do not interfere with each other during travel (normal state) or when the foot pedal is depressed and before locking. For this reason, the first arm 310 is provided with a notch 315 as a housing portion for housing the first flat portion 311A. The first flat portion 311A ​​and the stepped portion 311B, which are located closer to the fulcrum end than the stepped portion 311B, are shaped to fit snugly into the notch 315, and are housed therein in the normal state, as shown in FIG. 5 . In addition, in this stored state, the lower edge of the first flat surface 311A ​​of the second arm 311 is configured to come into contact with the first arm 310, and therefore also functions as a stopper that determines the stopping position of the returning first arm 310 in its normal state.

[0052] (Second Example) Next, another embodiment (second embodiment) of the parking brake mechanism will be described with reference to Fig. 11 and Fig. 12. Fig. 11 and Fig. 12 are both side views of the parking brake mechanism, Fig. 11 is a diagram showing a state in which the brake is not applied (unlocked state), and Fig. 12 is a diagram showing a state in which the brake is applied and locked.

[0053] Since the main structure of each part in this embodiment is the same as that of the embodiment already described (first embodiment), the following description will focus on the different parts. In the parking brake mechanism of this embodiment, the link mechanism includes a double-arm link member 500 and a link connector 510.

[0054] The double-arm link member 500 is rotatably fixed to the vehicle body by a fulcrum 502. The double-arm link member 500 has arms extending in two different directions. One is a longer long arm 500A, and the other is a shorter short arm 500B. These arms extend from the fulcrum 502 at a predetermined angle (opening angle) relative to each other. This opening angle is not particularly limited, but is preferably 60° to 120°, and more preferably 80° to 100°. If the opening angle is 120° or less, the entire link mechanism can be stored compactly and interference with other members is less likely to occur. If the opening angle is 60° or more, the amount of depression of the first arm 310 required to achieve the locked state can be reduced.

[0055] The tip of the long arm portion 500A of the double-arm link member 500 (the end opposite the fulcrum 502) is connected to the second pivot joint 144. The mechanism after the second pivot joint 144 (the mechanism connecting to the cam lever 240) is the same as in the first embodiment. Meanwhile, the tip of the short arm portion 500B of the double-arm link member 500 (the end opposite the fulcrum 502) is connected to the first arm 310 via a link connector 510. With this configuration, the displacement (depression amount) of the first arm 310 is amplified based on the ratio of the opening angle and lengths of the long arm portion 500A and the short arm portion 500B, and as a result, the cam lever 240 can be operated with a small displacement amount. In other words, the brake can be easily activated and a locked state can be created, further reducing the burden on the user.

[0056] It should be noted that when the brake is not applied, the double-arm link member 500 may unintentionally rotate counterclockwise. To prevent this unintentional rotation, a stopper 512 that protrudes from the vehicle body is provided on the outside of the short arm portion 500B of the double-arm link member 500. Even if the double-arm link member 500 attempts to rotate counterclockwise more than a predetermined amount, the outside of the short arm portion 500B abuts against the stopper 512, preventing further rotation.

[0057] The lengths from the rotation center of the two arms of the double-arm link member 500 may be the same. Alternatively, the short arm may be connected to the second pivot joint 144, and the long arm may be connected to the first arm 310 via the link connector 510, as opposed to this example. By adjusting the length and opening angle of the arms, the amount of movement (depression amount) of the first arm 310 until it reaches the locked state can be adjusted.

[0058] Next, the over-center locked state will be described. Fig. 12 is a diagram showing the parking brake mechanism in the locked state. The locked state is created by the relative arrangement of (1) fulcrum 149, which is the rotation fulcrum of the first arm, (2) connection fulcrum 506 with the first arm, which is one end of linear link connector 510, and (3) connection fulcrum 504 with double-arm link member 500, which is the other end of link connector 510. That is, when a third line 601 connecting connection fulcrum 504 and connection fulcrum 506 and a fourth line 602 connecting fulcrum 149 and connection fulcrum 506 exceed a straight line and become upwardly convex, the state becomes over-center, and first arm 310 is locked.

[0059] In the locked state, raised portion 310F provided at the tip of first arm 310 abuts against the underside of second arm 311. In this state, the lock can be released by stepping on and rotating second arm 311. Raised portion 310F has a function to adjust the abutment position, as well as a function to prevent first arm 310 from becoming larger overall and to prevent interference between components.

[0060] As described above, according to the parking brake mechanism of the second embodiment, the brake can be applied with a small depression amount to bring the vehicle into a fixed state, further reducing the burden on the user. [Explanation of symbols]

[0061] 20 frames 37 Drive wheels 40 axles 120 Parking brake mechanism 142 Link mechanism 143 First pivot joint 144 Second pivot joint 145 Position adjustment spring 148 Link Rod 151 Second Spring 152 Mounting plate 200 drum brake 240 Cam Lever 310 First Arm 311 Second Arm 500 Double-arm link member 510 link connector

Claims

1. A parking brake mechanism for a wheelchair with drive wheels, A cam lever for actuating the brake shoes of the drum brake; a first arm connected at one end to the cam lever via a link mechanism and rotatably supported; a second arm that abuts against the first arm when the first arm is fixed, When the other end of the first arm is pushed down, the first arm rotates to operate the cam lever, thereby actuating the drum brake, and the first arm is fixed in an over-center position due to the fulcrum arrangement of the link mechanism, When the second arm is pushed down in the fixed state, the first arm rotates in the opposite direction, and the fixed state is released. A parking brake mechanism for a wheelchair, configured so that the over-center position is determined by the second arm abutting against the first arm.

2. 2. The parking brake mechanism for a wheelchair according to claim 1, wherein the link mechanism includes an elastic member, and is configured so that when the fixed state is released, the first arm returns to the state before being pressed down.

3. 2. The parking brake mechanism for a wheelchair according to claim 1, wherein the one end of the first arm has a hook-shaped structure and is configured to determine the over-center position by fitting with the second arm.

4. 4. The parking brake mechanism for a wheelchair according to claim 3, wherein when the second arm is pushed down, an elastic force is stored in the second elastic member, and the elastic force causes the second arm to return to its state before being pushed down.

5. the second arm has a crank shape in a plan view, and overlaps with the first arm at a fulcrum end on a side that abuts against the first arm in a plan view; 5. The parking brake mechanism for a wheelchair according to claim 4, wherein the first arm is provided with a storage portion for storing the fulcrum end so that the fulcrum end and the first arm do not interfere with each other in the state before being pressed down.

6. 6. The parking brake mechanism for a wheelchair according to claim 5, wherein the fulcrum end is configured to function as a stopper that defines a stopping position of the first arm during the return movement of the first arm.

7. A parking brake mechanism for a wheelchair equipped with drive wheels, A cam lever for actuating the brake shoes of the drum brake; a first arm connected at one end to the cam lever via a link mechanism and rotatably supported; a second arm that abuts against the first arm when the first arm is fixed, When the other end of the first arm is pushed down, the first arm rotates to operate the cam lever, thereby actuating the drum brake, and the first arm is fixed in an over-center position due to the fulcrum arrangement of the link mechanism, When the second arm is pushed down in the fixed state, the first arm rotates in the opposite direction, and the fixed state is released. the link mechanism includes a double-arm link member rotatably supported on the vehicle body side, the dual-arm link member includes arms extending in two different directions from a rotation center, The cam lever is connected to one of the arms, the first arm is connected to the other arm portion via a link connector, A wheelchair parking brake mechanism in which, in the fixed state, the rotational fulcrum of the first arm, the first connecting fulcrum between the link connector and the first arm, and the second connecting fulcrum between the link connector and the double-arm link member are arranged over-center with respect to the first connecting fulcrum.

8. A wheelchair having a parking brake mechanism for wheelchairs according to any one of claims 1 to 7 attached to a driving wheel.

Images