Electromagnetic brake

Abstract: An electromagnetic brake provided with a braking force receiving bracket (8) for receiving tangent force (F t ) of a pair of brake shoes (6) and (7) reciprocating in approaching and parting directions mutually. The braking force receiving bracket (8) is fixed to a fixation member (10), slide faces (18), which receive side faces (6a) and (7a) of the pair of brake shoes (6) and (7) as the brake shoes (6) and (7) can slide, are provided on inner sides of the above bracket (8), and the above pair of brake shoes are surrounded by the bracket (8).

Description: This invention relates to an electromagnetic brake mainly used for a hoist gear. US-A-3 357 528 discloses an electromagnetic brake having the features which are recited in the preamble of claim 1. The prior art brake is used for braking an electric motor. As a conventional electromagnetic brake which has been used for a hoist gear, etc., a brake having a construction as shown in Figure 9 and Figure 10 is known. That is to say, as shown in Figure 9 and Figure 10, in a conventional electromagnetic brake, a U-shaped caliper 61 and an electromagnet portion 62 form a unit 63, and this unit 63 is attached to a fixation member 65 (for attachment) through a floating pin 64. A brake shoe 66 is attached to an end of the U-shaped caliper 61 through an adjusting screw 67, etc., and another brake shoe 68 is attached to an end of a push rod 69. This push rod 69 is fixed to a movable iron core 70 of the electromagnet portion 62, and the other end of the caliper 61 is fixed and connected to a fixed iron core 72 of the electromagnet portion 62 through an attachment bolt 71. When the electromagnet portion 62 is switched on, a braked body 73 such as a disk, shown with a two-dot broken line, pressed by the above-mentioned pair of brake shoes 66 and 68, performs brake-working. In this case, pressing force G of the brake shoe 66, pressing force H of the brake shoe 68, and tangent force (working in a direction at right angles with surface of Figure 9 or Figure 10) are transmitted through the adjusting screw 67, the caliper 61, the push rod 69, and the movable iron core 70. However, in a conventional electromagnetic brake as described above, a U-shaped large-volume caliper of block, having sufficient strength and rigidity, is required. And, there is a problem that construction of the brake becomes complicated, and width dimension of the brake in Figure 9 and Figure 10 becomes enlarged. It is therefore an object of the present invention to provide an electromagnetic brake with which the large-volume caliper of block is not necessary, light-weight apparatus in total and simplification of the construction can be obtained. This object is solved according to the present invention by electromagnetic brake including the features of claim 1. Preferred embodiments of the invention are described in the dependent claims. The present invention will be described with reference to the accompanying drawings, in which: Figure 1 is a left side view showing a preferred embodiment of the present invention; Figure 2 is a front view showing the preferred embodiment of the present invention; Figure 3 is a front view showing the preferred embodiment of the present invention with a part of cross-section; Figure 4A is an explanatory view showing an example of a braking force receiving bracket; Figure 4B is an explanatory view showing the example of the braking force receiving bracket; Figure 4C is an explanatory view showing the example of the braking force receiving bracket; Figure 5 is an explanatory view with cross-section of a principal portion; Figure 6 is an explanatory view with cross-section of a principal port ion; Figure 7 is an explanatory view with cross-section of a principal port ion; Figure 8 is an explanatory view with cross-section of a principal portion; Figure 9 is a front view showing a conventional example; and Figure 10 is a cross-sectional front view showing the conventional example. Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. In a left side view of Figure 1, a front view of Figure 2, and a front view with a part of cross-section of Figure 3, this electromagnetic brake has a construction in which a conventional caliper is omitted, and a unit U is formed instead by that a plate body 2 is arranged approximately parallel to an electromagnet portion 1 with a predetermined interval, and a fixed iron core 3 of the electromagnet portion 1 and the plate body 2 are connected and united through plural guiding rods 4. A braking force receiving bracket 8, for receiving tangent force F t of one pair of brake shoes 6 and 7. is arranged between the electromagnet portion 1 and the plate body 2 of the unit U. 9 shows a braked body such as a disc (discoid), a plate piece (of belt plate), etc. braked by press of the above-mentioned brake shoes 6 and 7. In the present invention, the tangent force F t is, among the force the brake shoes 6 and 7 receive from the braked body 9 in braking. a force in running direction of the braked body 9. In case that the braked body 9 rotationally moves, namely, is a disc, a force in a direction of tangent line works on the brake shoes 6 and T. This is called tangent force F t which is shown in Figure 1 with an arrow. And, in case that the braked body 9 linearly moves, the tangent force is in a direction of the linear movement. And, the braking force receiving bracket 8 is fixed to a fixation member 10 such as a base (base frame) of a hoist gear, a building, etc. That is to say, the former-described unit U is attached to the fixation member 10 through the bracket 8. The bracket 8 is, as shown in Figure 4, having a concave groove 11 to which the braked body 9 is inserted, and arch-shaped as a whole as shown in a front view of Figure 4A. And, each of left and right leg portions 12 is bifurcated into two branches by the existence of the above concave groove 11. And, a fitting portion 13 with tapped holes is formed on a lower end portion of the leg portion 12, and the bracket 8 is fixed to the above-mentioned fixation member 10 (as shown in Figure 1 through Figure 3) by screwing bolts into the tapped holes. And, the brake shoes 6 and 7 are held within an inner space 15 surrounded by the left and right leg portions 12 of the arch-shaped bracket 8 and an upper side portion 14. In Figure 5 through Figure 8, each of the brake shoes 6 and 7 is composed of a brake pad portion 16 which contacts the braked body 9 directly, and a brake shoe main body portion 17 to which the brake pad portion 16 is fixed. Both of the brake pad portion 16 and the brake shoe main body portion 17 are formed into a rectangular plate respectively, layered, and united. Slide faces 18, which receive side faces 6a and 7a of the brake shoes 6 and 7 at four corner portions of the brake shoes 6 and 7 as to slide in a press-working direction of the brake shoes 6 and 7 (a horizontal direction in Figure 3 and Figure 5), are formed on inner sides of the bracket 8. As described above, one pair of brake shoes 6 and 7 are surrounded by the bracket 8, able to slide in the press-working direction of the brake shoes 6 and 7, and held by the bracket 8 not to move in a direction of the tangent force F t . There is a merit that the brake shoes are stably held when the brake shoes 6 and 7 of rectangular plate are held at the four corner portions. And, the brake shoe 7 of the pair of brake shoes 6 and 7 is attached to a central part of the movable iron core 5 of the electromagnet portion 1 through a centripetal coupling 19. The other brake shoe 6 is attached to the plate body 2 side through an adjusting screw 20 and a centripetal coupling 21. Further, each one of a pair of return springs 22. continuously pushing the brake shoe 6 and the brake shoe 7 elastically in a direction the brake shoes 6 and 7 part each other, is disposed between the brake shoe 6 and the bracket 8, and the brake shoe 7 and the bracket 8. Concretely, the return spring 22 is made by punch press of a piece of steel plate, and the configuration of the return spring 22 is approximately rectangular from which plural leg pieces protrude, and having a short cylinder portion 23 on its center (refer to Figure 6). The centripetal coupling 19 or the centripetal coupling 21 is inserted to the short cylinder portion 23 as to slide. And, four of the plural leg pieces described above are J-shaped holding leg pieces 24 huggingly holding long sides of the rectangular brake shoe main body portion 17, and two of the leg pieces are L-shaped hitching leg pieces 25 and 26 hitching on short sides of the brake shoe main body portion 17. And, plate spring pieces 26 (four pieces in all), disposed above and below the hitching leg pieces 25 (in Figure 6), contact an outer face of the bracket 8, push the brake shoes 6 and 7 respectively in directions shown with arrows A (in Figure 5 and Figure 8) as the brake shoes 6 and 7 mutually part from. For this, concave-convex contact face (between a concave spherical face and a convex spherical face) of the centripetal couplings 19 and 21, and an end face of the adjusting screw 20 and the centripetal coupling 21 are kept not to generate small gaps, and noise generation is effectively prevented thereby when the brake is switched on and off. Next, the above-mentioned plate body 2, etc. are further concretely described with reference to Figures. The plate body 2 is approximately rhombus as shown in Figure 1, the adjusting screw 20 is attached to a lower end apex of the plate body 2, the guiding rods 4 are disposed on a left apex and a right apex of the plate body 2 respectively, and a reinforcing rod 27 is disposed on an upper apex. And, a lock nut 28 is screwed on the adjusting screw 20. As shown in Figure 5, the guiding rod 4 consists of a long bolt 29 and a cylinder body 30. The long bolt 29 is screwed into a tapped hole 31 of the fixed iron core 3, and both end portions of the cylinder body 30 are respectively press-fitted to a counterbore of the fixed iron core 3 and a counterbore of the plate body 2. Each of the above-described guiding rods 4 is inserted to each of holes 32 on both end part of the upper side of the arch-shaped bracket 8 shown in Figure 4, and an inner peripheral face of the hole 32 and a peripheral face of the cylinder body 30 can slide. And. in Figure 5. slide movement becomes smooth for slide bushings 33 inserted in the hole 32. As described above, the unit U, composed of the electromagnet portion 1, the plate body 2, and the guiding rods 4, is attached to the bracket 8 as to be able to float for a micro dimension. The reinforcing rod 27 prevents the plate body 2 from falling down, which is caused for strong reaction force (in the directions of the arrows A) when the brake shoes 6 and 7 press the braked body 9, in a direction that interval between the upper apex of the rhomboid plate body 2 and the electromagnet portion 1 decreases. In other words, a function of the reinforcing rod 27 is a function as a strut. A small protruding piece 34 is respectively formed on the left apex and the right apex of the rhomboid plate body 2 in Figure 1, and , on the other hand, a small protruding piece 35 similar to the small protruding piece 34 is respectively formed on a left end portion and a right end portion of the upper side of the bracket 8 in Figure 4. A tapped hole 35a is formed on the small protruding piece 35. As described above, the unit U is attached to the bracket 8 as to be able to float for a micro dimension, namely, as to move for a micro aperture B 1 and a micro aperture B 2 as shown in Figure 2. Figure 3, and Figure 5, and elastic members 36, which push the plate body 2 as to part from the bracket 8 (in a rightward direction in Figure 2). are provided. In Figure 2, the elastic member 36 consists of a pressed coil spring. Further, regulating members 37, which regulate the plate body 2 not to excessively move in the (above-described) parting direction, are provided. In Figure 2, the regulating member 37 is composed of a bolt 38 screwed into the former-described tapped hole 35a and a nut 39 (for locking). As described above, centering of the unit U is conducted with the elastic members 36 and the regulating members 37, and air gaps between the brake pad portions 16 of the brake shoes 6 and 7 and the braked body 9 (when not braked) can be regulated. Especially, there is a merit that simplification of the construction and cost reduction can be obtained when the elastic member 36 and the regulating member 37 are compactly united by insertion of the bolt 38 to the pressed coil spring as shown in Figure 2. And, although the unit U may incline to the heavy electromagnet portion 1 side in a floating state and the brake pad portions 16 may ununiformly contact (slide on) the braked body 9 such as a disc for the weight of the electromagnet portion 1 is heavy in comparison with the weight of the plate body 2, the above-described elastic members 36 ingeniously keep the balance of the unit U by pushing the plate body 2 in the direction that the plate body 2 parts from the fixed bracket 8. According to the electromagnetic brake of the present invention, the plate body 2 and the guiding rods 4 can be downsized and lightweight for the tangent force F 1 from the braked body 9 in braking is received through the braking force receiving bracket 8 and not transmitted to the plate body 2 and the guiding rods 4. And, a conventional large-volume caliper of block (refer to the mark 61 in Figure 9 and Figure 10) can be omitted, and simplification of the construction and compactification as a whole can be obtained. Especially, horizontal dimension in Figure 2 and Figure 3 can be reduced. And, gaps of concave-convex contact face of the centripetal coupling 21 and of the adjusting screw 20 are not generated, and working noise of switching on and off of brake can be reduced. And electromagnetic power of the electromagnet portion 1 can be fully utilized for the minimized gaps. And, the centripetal couplings 19 and 21 can be thin and having a simple structure. Further, centering of the unit U can be certainly conducted with a simple construction of the brake. Especially, the brake pad portions uniformly contact the braked body 9 because weight unbalance that the electromagnet portion 1 is heavy to the plate body 2 can be reduced with the elastic members 36. and the unit U is centered on the braked body 9. While preferred embodiments of the present invention have been described in this specification, it is to be understood that the embodiments are illustrative and not restrictive. Various modifications within the scope of the invention as laid down in the appended claims are possible.

Claims: An electromagnetic brake comprising a construction in which: a plate body (2) is disposed next to an electromagnet portion (1) with a predetermined interval; a fixed iron core (3) of the electromagnet portion (1) and the plate body (2) are connected and united with plural guiding rods (4), a braking force receiving bracket (8) for receiving one pair of brake shoes (6) and (7) and tangent force (F t ) of the pair of brake shoes (6) and (7) is disposed between the electromagnet portion (1) and the plate body (2), the guiding rods (4) being slidably received in the braking force receiving bracket (8); the braking force receiving bracket (8) is fixed to a fixation member (10); characterized in that one of the pair of brake shoes (6) and (7) is attached to a movable iron core (5) side of the electromagnet portion (1) through a centripetal coupling (19), and the other of the pair of brake shoes (6) and (7) is attached to the plate body (2) side through an adjusting screw (20) and another centripetal coupling (21); and concave and convex contact faces of each of the centripetal couplings (19) and (21) are held tightly fitting by one pair of return springs (22), continuously pushing the brake shoes (6) and (7) in directions that the brake shoes (6) and (7) mutually part from, each of which is disposed between each of the brake shoes (6) and (7) and the bracket (8). An electromagnetic brake as set forth in claim 1, wherein slide faces (18) receiving side faces (6a) and (7a) of the pair of brake shoes (6) and (7) as to slide are formed on inner sides of the bracket (8), and the brake shoes (6,7) are surrounded and held by the brake force receiving bracket (8). An electromagnetic brake as set forth in claims 1 or 2 comprising a unit (U) which is composed of said electromagnet portion (1) and said plate body (2), wherein said plural guiding rods (4) keep a predetermined interval there between, in which said braking force receiving bracket (8) is disposed; and a brake body (9) braked by press of the brake shoes (6,7); wherein the unit (U) is attached to the bracket (8) as to be able to float for a micro dimension; and centering of the unit (U) on said braked body (9) is conducted by elastic members (36), which elastically push the plate body (2) in a direction that the plate body (2) parts from the brake force receiving bracket (8), and regulating members (37), regulate the plate body's (2) movement so as to not allow excessive movement in the parting direction of the plate body (2) from the brake force receiving bracket (8).

Inventors: HIKARI KAZUO, HIKARI, KAZUO, Hikari, Kazuo, Sanyo Kogyo Co., Ltd.
Applicants: SANYO KOGYO CO LTD, SANYO KOGYO CO., LTD.
Application year: 1998
Main classification: F16D55
IPC codes: F16D55, F16D65, F16D59