Braking device, hand hoist and ratchet mechanism

Abstract

Provided is a brake device, a chain hoist, and a ratchet mechanism that can prevent a ratchet from reversing even when a switching knob is mistakenly operated in the return direction side during winding. The brake device (70) includes: a brake bracket (71) that is supported in a non-rotatable manner to a drive shaft (25) and has a flange portion (71a) and a shaft sleeve portion (71b); a female threaded member (35) that is shaft-supported to the shaft sleeve portion (71b) and is screwed to a male threaded portion (26) on the outer periphery of the drive shaft (25); a ratchet (80) that is sandwiched by the opposing flange portion (71a) and the female threaded member (35) and has a ratchet tooth (83) on the outer periphery side that limits the rotational direction to one direction; a brake plate (71a, 72b) that is disposed between at least one of the flange portion (71a) and the female threaded member (35) and the ratchet (80); and a pair of pawl members (90) that engage with the ratchet tooth (83) and are disposed at symmetric positions centered on the drive shaft (25). The ratchet (80) is provided with a high tooth (831) and a low tooth (832) that has a lower protrusion height from the center than the high tooth (831).

Description

TECHNICAL FIELD

[0001] The present application relates to a brake device, a lever hoist, and a ratchet mechanism. BACKGROUND

[0002] A lever hoist is widely used for the purpose of lifting and pulling in a load, or fixing a load (tightening a load) by a sling chain or the like. By operating a lever with a hand, the lever hoist can wind up (wind) and rewind (unwind) a chain. As such a lever hoist, for example, there is a type shown in Patent Literature 1. In the lever hoist disclosed in Patent Literature 1, by operating a lever, a driving member is driven, and a driving shaft is rotated by the driving member, thereby rotating a load sheave. Thereby, a load can be hoisted or lowered. Further, the lever hoist is provided with a switching knob, and by switching operation of the switching knob, it is possible to switch whether to transmit a driving force from the lever in a winding direction or in a rewinding direction.

[0003]

PRIOR ART DOCUMENTS

[0004]

PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2011-102182 SUMMARY

[0006] (Problems to be Solved by the Invention)

[0007] However, when winding operation of the lever hoist is performed, if the switching knob is mistakenly switched to the rewinding direction side, the brake mechanism can not function. Specifically, if the switching knob is mistakenly switched to the rewinding direction in a state where the front end of the pawl member is in abutment with the top end of the ratchet tooth of the ratchet wheel, under the action of the load, the ratchet wheel can start to rotate violently.

[0008] If the front end of the pawl member is made to enter between the tooth valleys of the ratchet teeth at the stage where the ratchet wheel starts to rotate, it is possible to stop the rotation of the ratchet wheel. However, if the switching knob is switched while the front end of the pawl member is in abutment with the top end of the ratchet tooth in a state where the ratchet wheel rotates violently, the next ratchet tooth (next tooth) will come earlier than the time required for the front end of the pawl member to enter between the tooth valleys, the pawl member collides with the top end of the next tooth and is bounced up, and thereafter the same state occurs, the front end of the pawl member does not enter between the tooth valleys, and thus it can not be possible to stop the rotation of the ratchet wheel. The structure disclosed in Patent Literature 1 is unable to stop such rotation of the ratchet wheel.

[0009] The present application has been achieved in view of the above-described circumstances, and aims to provide a brake device, a lever hoist, and a ratchet mechanism capable of stopping reverse rotation of a ratchet wheel.

[0010] (Means for solving the problems)

[0011] To solve the above problems, according to a first aspect of the present application, there is provided a brake device which prevents reverse rotation of a load sheave by stopping reverse rotation of a drive shaft which transmits rotation to the load sheave on which a chain is wound.

[0012] The brake device has the following features.

[0013] The brake device has the following features.

[0014] In addition, another aspect of the present application preferably includes the following in the above-mentioned application: the pawl member is provided in a pair, and the pair of pawl members is disposed at positions symmetrically centered on the drive shaft.

[0015] In addition, another aspect of the present application preferably includes the following in the above-mentioned application: the high teeth and the low teeth are alternately provided on the ratchet wheel.

[0016] In addition, another aspect of the present application preferably includes the following in the above-mentioned application: the number of the ratchet teeth is provided in an odd number of two times.

[0017] In addition, another aspect of the present application preferably includes the following in the above-mentioned application: the low tooth tip end portion on the low tooth tip end side is formed as a part of a circular arc.

[0018] In addition, to solve the above problems, according to a second aspect of the present application, there is provided a hand chain block having the following features.

[0019] The brake device according to the above-mentioned application is provided, and further includes: an operation lever which rotates with respect to the female screw member; a switching pawl for winding which is attached to the operation lever and engages with a switching gear in a winding direction, the switching gear being integrated with the female screw member; a switching pawl for unwinding which is attached to the operation lever and engages with the switching gear in an unwinding direction; and a switching knob which is provided integrally with the switching pawl for winding and the switching pawl for unwinding, and switches the switching gear to engage with either the switching pawl for winding or the switching pawl for unwinding.

[0020] In addition, in order to solve the above problems, according to a third aspect of the present application, there is provided a ratchet mechanism that allows a ratchet wheel to rotate in only one direction by providing the ratchet wheel with a plurality of ratchet teeth formed on an outer periphery, and at least one pawl member that engages with the ratchet teeth, the ratchet mechanism being characterized in that the ratchet teeth include high teeth and low teeth that have a lower protrusion height from the center of rotation of the ratchet wheel than the high teeth.

[0021] (EFFECT OF INVENTION)

[0022] According to the present application, it is possible to provide a brake device, lever hoist, and ratchet mechanism that can prevent reverse rotation of a ratchet wheel even when a switching knob is mistakenly operated in the return winding direction side during winding. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a front view showing an example structure of a lever hoist to which a power transmission device for a lever hoist is attached according to the present application.

[0024] Figure 2 is a sectional view showing the structure of the lever hoist shown in Figure 1

[0025] Figure 3 is an enlarged view of the vicinity of the brake device in the lever hoist shown in Figure 1

[0026] Figure 4 is a plan view showing the ratchet wheel and the pawl member in the lever hoist shown in Figure 1

[0027] Figure 5 is an enlarged view of the ratchet teeth of the ratchet wheel shown in Figure 4

[0028] Figure 6 is a plan view showing the ratchet wheel and the pawl member in the lever hoist shown in Figure 1 DETAILED DESCRIPTION

[0029] Hereinafter, a lever hoist 10 according to an embodiment of the present application will be described with reference to the drawings.

[0030] <OVERALL STRUCTURE OF LEVER HOIST>

[0031] ​​​​​In the following description, the X direction is set as the axis direction of the drive shaft 25 disposed between the gear box (omitted symbol) in which the reduction gear 30 is disposed and the rapid rotation handle 60 (hereinafter referred to as "idling handle"). The XI side is set as the side on which the idling handle 60 is mounted, and the X2 side is the gear box side opposite thereto. In addition, the Z direction is set as the vertical direction (suspension direction; winding and unwinding direction) in the suspended state of the hoist 10, the Zl side is set as the upper side in the suspended state, and the Z2 side is set as the lower side in the suspended state.

[0032] Figure 1 is a front view showing an example structure of the hoist 10. Figure 2 is a front view showing Figure 1 is a sectional view showing the structure of the hoist 10 shown in

[0033] As shown in Figure 2 The hoist 10 has a pair of frames 11, 12, and an upper hook 22 is supported on the upper side (Zl side) of the pair of frames 11, 12. In addition, a load sheave 20 on which the winding chain CI is wound is supported in a rotatable state between the pair of frames 11, 12. A load gear 21 that engages with a small-diameter gear portion 32 of a reduction gear 30 described later is integrally formed on the load sheave 20. In addition, an insertion hole 20a that penetrates in the axial direction (X direction) is formed in the load sheave 20, and a drive shaft 25 is inserted into the insertion hole 20a. A male screw portion 26 that engages with a female screw portion 35 described later is provided on the outer peripheral side of the drive shaft 25 at the middle, and a pinion gear 27 that engages with a large-diameter gear portion 31 of the reduction gear 30 is provided on the other end side (X2 side) of the drive shaft 25. In addition, the small-diameter gear portion 32 that engages with the load gear 21 described above is integrally provided on the reduction gear 30.

[0034] In addition, a housing 13 that protects the drive portions of the reduction gear 30 or the load gear 21 described above and the like is mounted on the frame 11. In addition, the male screw portion 26 engages with a female screw portion 36 of the female screw member 35. In the female screw member 35, in addition to the female screw portion 36, a switching gear 37 that can engage with a switching pawl 40 at a lower position (Z2 side) is provided on the peripheral portion thereof. The switching pawl 40 is, for example, a pawl in which one is provided on each of the one side and the other side of an operating lever 50 described later, and by rotating the operating lever 50 in a state in which the switching pawl 40 engages with the switching gear 37, the drive force is transmitted to the female screw member 35.

[0035] In addition, a switching knob 45 is mounted in a state coaxial with the switching pawl 40, and by switching operation of the switching knob 45, the transmission of the drive force to the female screw member 35 can be switched to the winding direction or the unwinding direction. For example, if the lower side (Z2 side) of the switching knob 45 is pushed towardFigure 1 When the left side of the center of the switching knob 45 is pushed to the winding direction, the switching pawl 40 for winding engages with the switching gear 37. Thus, in the case where the operation lever 50 is repeatedly rotated, the switching gear 37 rotates in the winding direction, but does not rotate in the rewinding direction. This corresponds to the winding state of the chain CI.

[0036] Further, as shown in the center of the above, a pair of engagement protrusions 46 is provided on the upper side (Zl side) of the above-mentioned switching knob 45. By the engagement of one of the pair of engagement protrusions 46 with the flange portion 65 of the idle handle 60, the idle handle 60 is not pulled out to one side (Xl side) in the axial direction (X direction). Thus, the state of the omitted force spring pressing brake mechanism can be maintained. Figure 1 On the other hand, for example, if the lower side (Z2 side) of the switching knob 45 is pushed to the rewinding direction, the switching pawl 40 for rewinding engages with the switching gear 37. Thus, in the case where the operation lever 50 is repeatedly rotated, the switching gear 37 rotates in the rewinding direction, but does not rotate in the winding direction. This corresponds to the rewinding state of the chain CI. Further, by the engagement of the other engagement protrusion 46 with the flange portion 65 of the idle handle 60, the idle handle 60 is not pulled out to one side (Xl side) in the axial direction (X direction). Thus, the state of the omitted force spring pressing brake mechanism can be maintained.

[0037] Figure 1

[0038] Further, if the lower side (Z2 side) of the switching knob 45 is positioned at a position between the winding direction and the rewinding direction, that is, a neutral position (in this case, the switching knob 45 is positioned in a direction along the length direction of the operation lever 50), the state where both the switching pawl 40 for winding and the switching pawl 40 for rewinding do not engage with the switching gear 37 is obtained. Thus, the state where even if the operation of rotating the operation lever 50 is performed, neither the winding nor the rewinding of the chain CI is performed, that is, a free (idling) state is obtained. At this time, neither of the pair of engagement protrusions 46 engages with the flange portion 65 of the idle handle 60. Thus, the idle handle 60 can be pulled out to one side (Xl side) in the axial direction (X direction), and thus the state of the omitted force spring pressing brake mechanism can be relaxed.

[0039] Further, on the drive shaft 25, a cam member 55 is installed in a state where it cannot rotate with respect to the drive shaft 25, and further, a member called an idle handle 60 is installed at a position on the side (Xl side) of the one end side in the axial direction (X direction) of the cam member 55 in a state where it cannot rotate with respect to the drive shaft 25.

[0040] ​​The idler handle 60 is a generally circular handle-shaped portion that can rotate with the drive shaft. A flange 65 is provided on the opposite side (X2 side) of the idler handle 60 in the axial direction (X direction). When either of the pair of engaging protrusions 46 engages with the flange 65, the idler handle 60 cannot be pulled out to the axial (X direction) side (X1 side). Therefore, the state of the force-applying spring-pressing braking mechanism (not shown) can be maintained.

[0041] like Figure 2 As shown, the idler handle 60 is pressed in towards the other side (X2 side) in the axial direction (X direction) when winding up and when rewinding. However, when the switching knob 45 is in the neutral position (neutral state), the idler handle 60 can be pulled out towards the side (X1 side) in the axial direction (X direction). When the idler handle 60 is pulled out towards the side (X1 side) in the axial direction (X direction), the pressing force of the force spring that applies force to the braking mechanism is reduced, thus changing to the brake release state. Therefore, the chain C1 can be freely pulled out in either direction of the winding side or the rewinding side while holding the chain C1 by hand or the like.

[0042] <Regarding the braking device 70>

[0043] Figure 3 It is an enlarged representation Figure 1 A partial cross-sectional view of the area near the braking device 70 in the lever hoist shown. Figure 2 and Figure 3 As shown, a braking device 70 is disposed between the operating lever 50 and the drive shaft 25. The braking device 70, as a main structural element, includes: a brake bracket 71, brake plates 72a and 72b, a ratchet 80, a pawl assembly 90, a pawl shaft 91, a bushing 92, etc.

[0044] The brake bracket 71 has a flange portion 71a and a hollow bushing portion 71b (corresponding to the bushing portion). The flange portion 71a is configured to have a diameter larger than that of the hollow bushing portion 71b, and it is able to abut against the brake plate 72a.

[0045] The hollow bushing portion 71b is located further from the female threaded member 35 (X1 side) than the flange portion 71a, and it supports the ratchet 80 via the bushing 92. In addition, the inner circumference of the hollow bushing portion 71b engages with the drive shaft 25 via a key connection or spline connection, thereby allowing the drive shaft 25 and the brake bracket 71 to rotate integrally.

[0046] Furthermore, brake plates 72a and 72b are axially supported on the hollow bushing portion 71b between the flange portion 71a and the ratchet 80, and between the internal threaded component 35 and the ratchet 80, respectively. The brake plates 72a and 72b are friction members formed, for example, by sintering a specified material.

[0047] Here, when a load is applied to the drive shaft 25 in the winding direction, the female threaded member 35 presses down on the brake plates 72a and 72b through the threaded fastening action between the female threaded member 35 and the brake bracket 71 (flange 71a). As a result, the brake plates 72a and 72b are forcefully pressed down, and the ratchet 80 is also forcefully pressed down by the brake plates 72a and 72b. Here, since the ratchet pawl member 90 is locked onto the ratchet 80, thus preventing the ratchet 80 from rotating in the winding direction, the rotation of the drive shaft 25 in the winding direction is suppressed by the aforementioned forceful pressing.

[0048] Furthermore, if the switching knob 45 is switched to the winding direction and the operating lever 50 is operated, the ratchet 80 can rotate in the winding direction, and therefore, this rotation in the winding direction will not be blocked by the ratchet 80. Thus, by operating the operating lever 50, the female threaded component 35, brake plates 72a and 72b, ratchet 80, and brake bracket 71 become a single unit, causing the drive shaft 25 to rotate. Its driving force is transmitted to the load pulley 20 via the reduction gear 30, thereby winding up the chain C1.

[0049] On the other hand, when the switching knob 45 is switched in the rewinding direction and the operating lever 50 is operated, the female threaded component 35 rotates by an amount corresponding to the operation amount, thereby easing the thread tightening action of the brake bracket 71. Therefore, the braking force on the ratchet 80 is released corresponding to the operation amount of the operating lever 50 (i.e., the rotation amount of the female threaded component 35), thus causing the brake bracket 71 and drive shaft 25 to rotate in the rewinding direction. This driving force in the rewinding direction is transmitted to the load pulley 20 via the reduction gear 30, thereby causing the chain C1 to rewind.

[0050] Additionally, the ratchet teeth 83 (described later) provided on the ratchet 80 engage with the front end 90a of the pawl member 90. This engagement constitutes a ratchet mechanism configured such that, except when the switching knob 45 is switched in the winding direction and the operating lever 50 is operated, the ratchet 80 is prevented from rotating in the winding direction and is allowed to rotate in the coiling direction.

[0051] In addition, such as Figure 3 As shown, a bushing 92 is provided on the outer periphery of the hollow bushing portion 71b of the brake bracket 71, and a ratchet 80 is provided on the outer periphery of the bushing 92.

[0052] In addition, a pawl shaft 91 is attached to the frame 12, and the pawl member 90 is rotatably supported to the pawl shaft 91. In addition, a coil portion 93a of a torsion spring 93 is attached to the pawl shaft 91, and the torsion spring 93 applies a force in a direction in which the pawl member 90 is pressed against the teeth 83 (described later) of the ratchet wheel 80. In addition, the pawl member 90 is provided in a pair, and is arranged in a point symmetry with respect to the center axis of the drive shaft 25 in the circumferential direction of the ratchet wheel 80.

[0053] <Regarding the Ratchet Wheel 80>

[0054] Next, the structure of the ratchet wheel 80 will be described. Figure 4 is a plan view of the ratchet wheel 80 and the pawl member 90, and is a view of an example structure in which the number of teeth 83 is an odd number of two times, and is a plan view showing the arrangement of the pawl member 90. As shown in Figure 4 As shown in FIG. 8, the annular portion 81 is provided on the ratchet wheel 80, and the surface and the back surface of the annular portion 81 are portions that are pressed by the brake plates 72a and 72b described above. In addition, the ratchet wheel 80 is supported so as to be rotatable by locating the bushing 92 in a position described below, that is, in the center hole 82 at the center of the annular portion 81.

[0055] The teeth 83 are formed so as to protrude from the annular portion 81 toward the outer circumferential side. Figure 5 is an enlarged view of the vicinity of the teeth 83 of the ratchet wheel 80. As shown in Figure 5 As shown in FIG. 9, the teeth 83 include high teeth 831 and low teeth 832. Among them, the tip end portion (high tooth tip end portion 831a) of the high teeth 831 protrudes more to the outer diameter side than the tip end portion (low tooth tip end portion 832a) of the low teeth 832. Therefore, the front end portion 90a of the pawl member 90 is configured so that the position at which the front end portion 90a contacts the low tooth tip end portion 832a under the action of the force of the torsion spring 93 is more toward the radial center side (inner diameter side) than the position at which the front end portion 90a contacts the high tooth tip end portion 831a.

[0056] In this embodiment, high teeth 831 and low teeth 832 are formed alternately adjacent to each other, and their circumferential lengths (tooth pitch) are set to be equal. Furthermore, when the portion between high teeth 831 and low teeth 832 is designated as a tooth valley 833, the inclination angle of the tapered portion 831b of the high tooth tip portion 831a from the tooth valley 833 toward the tip side of the high tooth 831 is set to be equal to the inclination angle of the tapered portion 832b of the low tooth tip portion 832a from the tooth valley 833 toward the tip side of the low tooth 832. Therefore, in this embodiment, the low tooth 832 is configured such that the tip side of the high tooth 831 is cut off. Additionally, the low tooth tip portion 832a of the low tooth 832 can also be part of an arc concentric with the ratchet 80. However, the low tooth tip portion 832a can also be a shape other than part of an arc (e.g., a straight line), or it can be part of an arc not concentric with the ratchet 80.

[0057] Furthermore, the number of teeth in the ratchet 83, after combining the high teeth 831 and the low teeth 832, is an even number. Here, as... Figure 4 As shown, when the number of teeth on the ratchet 83 is an odd multiple of 2, when the front end 90a of one pawl member 90 is pressed against the high tooth 831, the other pawl member 90 is pressed against the low tooth 832. Since either one pawl member 90 or the other pawl member 90 must be pressed against the low tooth 832, when reversal occurs, at least the front end 90a of the pawl member 90 pressed against the low tooth 832 must collide with the back of the high tooth 831 adjacent to that low tooth. Therefore, reversal of the ratchet 80 can be reliably prevented. Furthermore, in Figure 4 In the structure shown, the ratchet 83 has a total of 22 teeth, but the number of teeth in the ratchet 83 can be any number as long as it is twice an odd number.

[0058] However, as Figure 6 As shown, when the number of teeth in the ratchet 83, which includes both high teeth 831 and low teeth 832, is a multiple of an even number (a multiple of 4), when the front end 90a of one pawl member 90 is pressed against the high tooth 831, the other pawl member 90 is also pressed against the high tooth 831. Similarly, when the front end 90a of one pawl member 90 is pressed against the low tooth 832, the other pawl member 90 is also pressed against the low tooth 832. In this case, when reversal occurs, the front end 90a of the pawl member 90 pressed against the low tooth 832 will inevitably collide with the back of the high tooth 831 adjacent to that low tooth, or, regarding the front end 90a of the pawl member 90 pressed against the high tooth 831, since the spacing between adjacent high teeth 831 is larger than the spacing of ratchet teeth of the same height in the conventional ratchet, it is possible to sufficiently prevent the ratchet 80 from reversing. Furthermore, in Figure 6In the illustrated structure, the number of teeth of the ratchet 83 is 20 in total, but the number of teeth of the ratchet 83 can be any number as long as it is an even number of 2.

[0059] <Regarding the Effects>

[0060] The brake device 70 and the hand chain block 10 configured as above have: the brake bracket 71 supported to the drive shaft 25 in a non-rotatable manner, and having a flange portion 71a and a hollow shaft portion 71b (shaft sleeve portion); the female screw member 35 supported to the drive shaft 25 in a rotatable manner, and screwed with the male screw portion 26 provided to the outer periphery of the drive shaft 25; the ratchet wheel 80 held by the opposed flange portion 71a and the female screw member 35, and having a ratchet 83 for limiting the rotational direction to one direction on the outer periphery side; the brake plates 72a, 72b arranged between at least one of the flange portion 71a and the female screw member 35 and the ratchet wheel 80; and at least one pawl member 90 engaged with the ratchet 83, and having a front end portion 90a (front end side) engaged in a tooth valley portion 833 between adjacent ratchets 83, respectively. The ratchet wheel 80 is provided with a high tooth 831 and a low tooth 832 having a protrusion height from the rotational center of the ratchet wheel 80 lower than that of the high tooth 831.

[0061] Here, a case where the switching knob 45 is mistakenly switched in the return winding direction is considered in a state where the front end portion 90a of the pawl member 90 is in contact with the high tooth top end portion 831a of the high tooth 831 on the top end side. In this case, the ratchet wheel 80 starts to rotate (reverse) violently under the action of the load of the cargo. However, as described above, the high tooth 831 and the low tooth 832 are formed in the ratchet wheel 80. Therefore, the front end portion 90a of the pawl member 90 after passing the low tooth top end portion 832a of the low tooth 832 collides with the back of the high tooth 831 adjacent to the low tooth, and thus the reverse rotation of the ratchet wheel 80 can be prevented.

[0062] Further, in the present embodiment, it is preferable that the high tooth 831 and the low tooth 832 are alternately provided on the ratchet wheel 80. In the case of being configured as such, when the front end portion 90a of the at least one pawl member 90 is in contact with the low tooth top end portion 832a of the low tooth 832, if the ratchet wheel 80 starts to rotate (reverse), it immediately collides with the back of the high tooth 831 as the next tooth. Further, when the front end portion 90a of the at least one pawl member 90 is in contact with the high tooth top end portion 831a of the high tooth 831, even if the ratchet wheel 80 starts to rotate (reverse) and passes the low tooth top end portion 832a, it is immediately collides with the back of the high tooth 831. Therefore, the reverse rotation of the ratchet wheel 80 can be prevented at an early stage.

[0063] Further, in the present embodiment, it is preferable that the ratchet teeth 83 be provided with an odd number of two times. In the case of being thus configured, when the front end portion 90a of one pawl member 90 is pressed against the high tooth 831, the other pawl member 90 is pressed against the low tooth 832. By causing either one of the one pawl member 90 or the other pawl member 90 to be necessarily pressed against the low tooth 832, even if the ratchet wheel 80 is reversed at a speed exceeding the intended speed, it is possible to press the front end portion 90a of one of the pawl members 90 against the low tooth tip end portion 832a in the ratchet wheel 80 which is more on the inner diameter side than the high tooth tip end portion 831a, and thus it is possible to reliably prevent the reversal of the ratchet wheel 80.

[0064] Further, in the present embodiment, the low tooth tip end portion 832a on the tip end side of the low tooth 832 can be configured to form a portion of a circular arc. In the case of being thus configured, the circumferential direction length of the low tooth tip end portion 832a is longer than the circumferential direction length of the high tooth tip end portion 831a. Therefore, compared with the high tooth tip end portion 831a, it is possible to lengthen the time during which the front end portion 90a of the pawl member 90 is in contact with the low tooth tip end portion 832a, and thus it is possible to more reliably prevent the reversal of the ratchet wheel 80. Further, since it is possible to easily machine the low tooth tip end portion 832a using, for example, a machine tool, it is possible to improve the productivity.

[0065] <Modification Example>

[0066] The above describes each embodiment of the present application, but the present application can be variously modified in addition to this. The following describes this.

[0067] In the above-described embodiment, the idle device which switches between idle and non-idle by operating the idle handle 60 is described, but a chain hoist with an idle device having another mode such as an automatic idle mode can also be used.

[0068] Further, in the above-described embodiment, the case where the brake device 70 is applied to the chain hoist 10 is described. However, the above-described brake device can also be applied to hoists other than chain hoists such as chain hoists.

[0069] Further, in the above-described embodiment, the case where one pair of pawl members 90 is provided is described. However, with respect to the pawl members 90, one can be provided, or three or more can be provided. When three or more pawl members 90 are provided, it is preferable to be configured such that the pawl members 90 are uniformly arranged on the outer peripheral side of the ratchet wheel 80, and when one pawl member 90 engages with the tooth valley portion between the ratchet teeth adjacent to the high tooth, the other pawl member 90 engages with the tooth valley portion between the ratchet teeth adjacent to the low tooth.

[0070] However, the plurality of pawl members 90 can not be uniformly arranged on the outer circumferential side of the ratchet wheel 80. In this case, it is preferable that the radial forces acting on the pawl shafts 21 of the respective pawl members 90 be equal. For example, when four pawl members 90 are provided, two of the pawl members 90 can be arranged in line symmetry with respect to a line perpendicular to the drive shaft 25. By arranging the four pawl members 90 so that the radial forces acting on the pawl shafts 21 thereof are equal, the force acting on the ratchet wheel 80 from the pawl members 90 is dispersed, and thus the durability of the ratchet wheel 80 can be improved. Further, by arranging the pawl members 90 in this manner, the deviation of the force acting on the drive shaft 25 from the ratchet wheel 80 can be reduced, and as a result, the durability of the drive shaft 25 or the surrounding members thereof can also be improved.

[0071] Further, it is most preferable that the pawl members 90 be provided in pairs, and the pair of pawl members 90, 90 be arranged in the same shape at positions that are point-symmetric with respect to the drive shaft 25, but as long as the shape and arrangement are such that the front end portions 90a of the respective pawl members 90 simultaneously engage the respective tooth valley portions 833, the pawl members 90 can be formed in different shapes. For example, by uniformly arranging two or more pawl members 90 on the outer circumferential side of the ratchet wheel 80, the force applied to one pawl member 90 can be dispersed, and the radial force applied to the pawl shaft 91 on which the ratchet wheel 80 is arranged can be reduced. Of these, it is most preferable that the engagement positions of the front end portions 90a actually be point-symmetric positions, although the positions can be offset by an even number of teeth from each other, but if the offset amount is large, the load applied to the drive shaft 25 increases, and thus it is not desirable to offset the engagement positions by more than necessary.

[0072] Further, in the above-described embodiment, the brake plate 72 and the ratchet wheel 80 are arranged as separate bodies, but a friction member or the like can be sintered on both surfaces of the ratchet wheel 80.

[0073] Further, in the above-described embodiment, the female threaded member 35 of the ratchet wheel 80 is pressed by the load torque acting on the drive shaft 25, and the male thread 26 of the drive shaft 25 is screwed with the female thread 36 of the female threaded member 35. However, the female threaded member 35 can be provided as a separate body from the drive shaft 25 (for example, a male thread provided on the outer circumferential portion of a hollow shaft formed by extending the hollow boss portion 71b of the brake carrier 71), and further, it can be a mechanism that converts the load torque into an axial force using a cam.

[0074] Further, in the above-described embodiment, the brake device 70 of the hand winch 10 is described as an example, but if the present application is understood more broadly, the present application can be said to relate to a ratchet mechanism. That is, the ratchet mechanism of the present application, which permits rotation of a ratchet in only one direction by providing the ratchet with a plurality of ratchet teeth formed on the outer periphery and at least one pawl member engaging with the ratchet teeth, wherein the ratchet teeth include high teeth having a high protrusion height from the center of the ratchet and low teeth having a low protrusion height from the center of the ratchet.

[0075] By thus configuring the ratchet mechanism, even when the front end of the pawl member is located at the top end of the high teeth or the low teeth at the time of reversal, the front end of the pawl member collides with the back of the next high teeth (the inclined portion forming the high teeth) and enters the tooth valley portion between the ratchet teeth. Therefore, reversal of the ratchet can be immediately and reliably prevented.

[0076] Here, as shown in FIG. 1, it is preferable that two pawl members be provided at symmetric positions. Further, it is preferable that the high teeth and the low teeth be alternately arranged. Further, it is preferable that the ratchet teeth be provided in an odd number of twice the number. Figure 4

[0077] Further, by providing two pawl members at symmetric positions, deviation of stress applied to the ratchet can be eliminated. Further, by alternately arranging the high teeth and the low teeth, when reversal occurs, the front end of the pawl member can be caused to collide with the back of the high teeth located closest. Further, by providing the ratchet teeth in an odd number of twice the number, when the front end of one of the pawl members located at a symmetric position is located at the top end of the high teeth, the front end of the other pawl member is located at the top end of the low teeth, whereby when reversal occurs, the front end of at least the pawl member located at the top end of the low teeth will certainly collide with the back of the high teeth adjacent to the low teeth, and therefore, reversal of the ratchet can be immediately and reliably prevented.

[0078] Such a ratchet mechanism is, for example, applied to the brake device of the hand winch described in the above-described embodiment, which resists input torque in one direction, and is particularly effective for preventing reversal of the ratchet constituting the brake device.

[0079] (Symbol Description)

[0080] 10... hand winch

[0081] 11... frame

[0082] 12... frame

[0083] 13... housing

[0084] 20... load sheave

[0085] 20a... insertion hole

[0086] ​21 … load gear

[0087] 22 … upper hook

[0088] 25 … drive shaft

[0089] 26 … male screw part

[0090] 27 … pinion

[0091] 30 … reduction gear

[0092] 31 … large-diameter gear part

[0093] 32 … small-diameter gear part

[0094] 35 … female screw part

[0095] 36 … female screw part

[0096] 37 … shift gear

[0097] 40 … shift pawl

[0098] 45 … shift knob

[0099] 46 … engagement protrusion

[0100] 50 … operating lever

[0101] 55 … cam part

[0102] 60 … idle handle

[0103] 65 … flange part

[0104] 70 … brake device

[0105] 71 … brake carrier

[0106] 71a … flange part

[0107] 71b … hollow boss part (corresponding to boss part)

[0108] 72a … brake plate

[0109] 72b … brake plate

[0110] 80 … ratchet

[0111] 81 … annular part

[0112] 82 … central hole

[0113] 83 … ratchet teeth

[0114] 90 … pawl part

[0115] 90a … front end part

[0116] 91 … pawl shaft

[0117] 92 bush

[0118] 93 torsion spring

[0119] 93a coil portion

[0120] 831 high tooth

[0121] 831a high tooth tip portion

[0122] 831b tapered portion

[0123] 832 low tooth

[0124] 832a low tooth tip portion

[0125] 832b tapered portion

[0126] 833 tooth valley portion

[0127] C1 chain

Claims

1. A brake device that prevents a reverse rotation of a load pulley to which a chain is wound by stopping a reverse rotation of a drive shaft that transmits a rotation to the load pulley, the brake device characterized by providing: a brake bracket that is supported to the drive shaft in a non-rotatable manner and has a flange portion and a boss portion, a female threaded member that is supported to the drive shaft in a rotatable manner and is screwed with a male threaded portion provided to an outer periphery of the drive shaft, a ratchet wheel that is held by the flange portion and the female threaded member that are opposed to each other and has a ratchet tooth on an outer periphery side for limiting a rotation direction to one direction, a brake plate that is arranged between at least one of the flange portion and the female threaded member and the ratchet wheel, and at least one pawl member that engages with a tooth valley portion between adjacent ratchet teeth and engages with the ratchet tooth on a leading end side thereof; the ratchet tooth is provided with a high tooth and a low tooth that has a protrusion height from a rotation center of the ratchet wheel lower than the high tooth, the high tooth and the low tooth are alternately adjacent and a tooth pitch in a circumferential direction is set to be equal, the ratchet tooth is provided with an odd number of 2 times, whereby when a leading end of one of the pawl members is located at a top end of the high tooth in a symmetrical position, a leading end of the other pawl member is located at a top end of the low tooth.

2. The brake device according to claim 1, characterized in that the pawl member is provided with a pair, and the pair of the pawl members is arranged at positions that are symmetrical with the drive shaft as a center.

3. The brake device according to claim 1 or 2, characterized in that the high tooth and the low tooth are alternately provided on the ratchet wheel.

4. The brake device according to claim 1 or 2, characterized in that a low tooth top end portion on a top end side of the low tooth is formed as a part of a circular arc.

5. The brake device according to claim 3, characterized in that a low tooth top end portion on a top end side of the low tooth is formed as a part of a circular arc.

6. A hand chain hoist, characterized by providing the brake device according to any one of claims 1 to 5, and providing: an operation lever that rotates with respect to the female threaded member, a winding switching pawl that is attached to the operation lever and engages with a switching gear in a winding direction, the switching gear and the female threaded member being integrated, an unwinding switching pawl that is attached to the operation lever and engages with the switching gear in an unwinding direction, and a switching knob that is provided integrally with the winding switching pawl and the unwinding switching pawl and switches which one of the winding switching pawl and the unwinding switching pawl engages with the switching gear.

7. A ratchet mechanism for the brake device according to claim 1, the ratchet mechanism permitting only a rotation of a ratchet wheel in one direction by providing the ratchet wheel having a plurality of ratchet teeth formed on an outer periphery and at least one pawl member that engages with the ratchet teeth, the ratchet mechanism characterized by The ratchet is provided with high teeth and low teeth having a projection height from the center of rotation of the ratchet lower than the high teeth, the high teeth and the low teeth being alternately adjacent and the tooth pitch in the circumferential direction being set to be equal.

Images