JP3823827B2 - Eddy current reducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an eddy current type reduction gear used mainly as an auxiliary brake in a large vehicle, and more particularly to an eddy current type reduction gear designed to prevent malfunction.
[0002]
[Prior art]
In large vehicles such as trucks, an eddy current reduction device (retarder) is generally used as an auxiliary brake.
[0003]
A schematic configuration of the eddy current type speed reducer will be described with reference to FIGS.
[0004]
FIG. 7 shows a front sectional view of the upper half of the eddy current speed reducer, which includes a cylindrical braking drum 2 connected to a rotary shaft 1 such as an output shaft of a vehicle transmission, An annular casing 3 disposed inside the brake drum 2 and connected to a fixed side such as a gear box of a transmission, and an inner space 4 of the annular casing 3 are provided so as to be rotatable in the circumferential direction. A support ring 6 that supports a plurality of magnets 5 and an actuator (air cylinder) 7 that rotates the support ring 6 in the circumferential direction are provided.
[0005]
The brake drum 2 includes a boss 8, a spoke 9, and a cylindrical portion 10, and the cylindrical portion 10 is formed of a magnetic material (for example, steel). A flange 8a of the boss 8 is fastened together with a brake drum 11 of a parking brake to a mounting flange 12 that is spline-fitted to the rotary shaft 1 by a plurality of bolts and nuts, and the brake drum 2 is integrated with the rotary shaft 1. Rotate to. In addition, heat radiating fins 13 are provided on the outer peripheral portion of the cylindrical portion 10.
[0006]
The annular casing 3 is made of a non-magnetic material (for example, aluminum), and a pole piece (switch plate) 15 made of a ferromagnetic material such as low carbon steel is provided on the outer peripheral wall 14 of the cylindrical casing 10 of the brake drum 2. A plurality are provided at equal intervals in the circumferential direction so as to face the surface.
[0007]
A support ring 6 made of a magnetic material is provided in the inner space 4 of the annular casing 3 so as to be rotatable in the circumferential direction with respect to the annular casing 3, and a magnet 5 is disposed on the outer periphery of the support ring 6. A plurality of pieces 15 are arranged at equal intervals in the circumferential direction so as to face the pieces 15 from the inside. As shown in FIGS. 8A and 8B, the magnet 5 is provided so that two magnets 5 are opposed to one pole piece 15, and on the side facing the pole piece 15. They are arranged so that the polarities differ every two pieces.
[0008]
As shown in FIG. 7, the support ring 6 is rotated at one end (the left end in the figure) of the support ring 6 so that the braking force is applied to the braking drum 2, and the braking force is applied. An actuator 7 for switching the non-operating state that is not allowed to be connected is connected.
[0009]
When not operating, the actuator 7 rotates the support ring 6 so that the polarities of the two magnets 5 facing the pole piece 15 are different from each other, as shown in FIG. As a result, a short circuit magnetic circuit w1 is formed by the magnet 5, the pole piece 15 and the support ring 6, and the magnetic circuit does not act on the brake drum 2. Therefore, no braking force acts on the braking drum 2.
[0010]
On the other hand, during operation, the actuator 7 rotates the support ring 6 by one pitch p of the magnet 5 from the state shown in FIG. 8A, and as shown in FIG. The two magnets 5 facing each other are made to have the same polarity. As a result, the magnetic circuit w <b> 2 is formed by the magnet 5, the two adjacent pole pieces 15, the braking drum 2 (more specifically, the cylindrical portion 10), and the support ring 6. As a result, an eddy current is generated in the cylindrical portion 10 of the brake drum 2 and a braking force acts on the brake drum 2.
[0011]
By the way, in such an eddy current type reduction gear, since the inner peripheral surface of the support ring 6 and the outer peripheral surface of the inner peripheral wall 16 of the annular casing 3 are sliding surfaces, a drive bush (sliding member) is provided between them. 17 is inserted (press-fit). The drive bush 17 is mainly formed of a fluororesin such as Teflon (registered trademark) or PTFE. The drive bush 17 formed of the fluororesin is slid as shown in the graph of FIG. The friction coefficient μ increases when the contact surface pressure Pm with the object (here, the support ring 6 and the annular casing 3) is low, and the friction coefficient μ decreases as the contact surface pressure Pm increases. . Therefore, it is necessary for the drive bush 17, the support ring 6 and the annular casing 3 to contact and slide at an appropriate contact surface pressure. That is, if the contact surface pressure with the drive bush 17 is too small, the coefficient of friction increases, the temperature becomes high, and there is a risk of malfunction such as the support ring 6 being fixed.
[0012]
Therefore, the present applicant has invented an eddy current type speed reducer as disclosed in Japanese Patent Application No. 2000-2963 to solve this problem. This is because, as shown in FIG. 7, a recess 18 is formed in the axially central portion of the outer peripheral surface of the inner peripheral wall 16 of the annular casing 3, and the sliding portion between the drive bush 17 and the inner peripheral wall 16 of the annular casing 3. (Contact portion) An appropriate contact surface pressure is ensured by reducing the areas of 20a and 20b.
[0013]
[Problems to be solved by the invention]
However, in this eddy current type speed reducer, the area of the sliding part 20a on the one end side of the support ring 6, that is, the side to which the actuator 7 is connected, and the area of the sliding part 20b on the other end side are substantially equal. As a result, it was found that the following problems occur.
[0014]
That is, since the actuator 7 cantileverly supports the support ring 6 on one end side in the axial direction, the load applied to the drive bush 17 when the support ring 6 rotates is closer to the one end side where the actuator 7 is provided. Is higher and lowers toward the other end side. Therefore, the contact surface pressure between the drive bush 17 and the inner peripheral surface of the support ring 6 and the inner peripheral wall 16 of the annular casing 3 is also higher on the one end side and lowers toward the other end side. On the other hand, since the area of the sliding portion 20a on the one end side is almost equal to the area of the sliding portion 20b on the other end side, the contact surface pressure is insufficient in the sliding portion 20b on the other end side. As a result, the friction coefficient of the drive sash 17 increases and the temperature becomes high. As a result, the support ring 6 may be fixed and malfunction may occur. In particular, in a single-row eddy current reduction device having a single magnet row in the axial direction, the axial lengths of the magnet 5 and the support ring 6 need to be increased to some extent in order to ensure braking force. This problem becomes significant.
[0015]
Accordingly, an object of the present invention is to solve the above-mentioned problems, to optimize the contact surface pressure between the sliding member (drive bush) and the support ring and / or the annular casing, and to prevent the occurrence of malfunction. It is to provide a reduction gear.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, the present invention includes a brake drum coupled to a rotating shaft, and a pole piece connected to the fixed side inside the brake drum and provided to face the inner peripheral surface of the brake drum. An annular casing provided, and a support ring provided with a plurality of magnets provided in the circumferential direction so as to be opposed to the pole piece from the inside, provided in an inner space of the annular casing so as to be rotatable in the circumferential direction; A drive bush, which is interposed between the inner peripheral surface of the support ring and the inner peripheral wall of the annular casing, is connected to the one end side in the axial direction of the support ring and the support ring is rotated. in eddy current retarder device including an actuator, and the dry bush, the sliding portion between the supporting ring and / or annular casing, as well as a plurality formed in the axial direction, their sliding portion It is obtained by reducing the area towards the sliding portion positioned on the other axial end portion side of the sliding portion positioned in the axial direction one end side of the upper Symbol support ring.
[0017]
Here, it is preferable that the axial length of the sliding portion located on the other end side in the axial direction of the support ring is shorter than the axial length of the sliding portion located on the one end side in the axial direction.
[0018]
In addition, the drive bush is formed over substantially the entire axial direction of the support ring, and a recess is formed in the axially central portion of the inner peripheral surface of the support ring and / or the inner peripheral wall of the annular casing. The sliding portions may be formed on both side portions in the axial direction of the hollow portion.
[0019]
Further, the dry bush, and one axial end side of the support ring may be provided respectively on the other axial end side.
[0020]
Further, in the inner peripheral surface and / or inner peripheral wall of the annular casing of the support ring, each dry bush to form each recess in the central portion of the part located, sliding respectively in opposite axial ends of each dry bushes A moving part may be formed.
[0021]
Further, a wear resistance improving member may be provided on the outer peripheral surface of the inner peripheral wall of the annular casing.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.
[0023]
FIG. 1 is a partially enlarged sectional view of an eddy current type speed reducer according to this embodiment. Since the basic configuration of the eddy current reduction device of the present embodiment is the same as that shown in FIG. 7, the same reference numerals are given to the same elements, and descriptions thereof are omitted.
[0024]
The present invention is obtained by improving the sliding portion between the sliding member (drive bush) and the support ring and / or the annular casing, which will be described in detail below.
[0025]
As shown in FIG. 1, an annular casing 3 connected to a fixed side such as a gear box (not shown) of a transmission is arranged inside a brake drum 2 connected to a rotating shaft (not shown). Yes. The annular casing 3 is made of a non-magnetic material such as aluminum, and a pole piece made of a ferromagnetic material such as low-carbon steel so that the outer peripheral wall 14 faces the inner peripheral surface of the cylindrical portion 10 of the brake drum 2 ( Switch plates) 15 are provided at equal intervals in the circumferential direction. A support ring 6 is disposed in the inner space 4 of the annular casing 3 so as to be rotatable in the circumferential direction, and a plurality of magnets 5 are provided on the outer periphery of the support ring 6 along the circumferential direction. . In the present embodiment, it is a so-called single-row eddy current reduction device having one magnet row in the axial direction of the annular casing 3. On one end side (left side in the figure) of the support ring 6, an actuator (for example, switching between an operation state in which the support ring 6 is rotated to apply a braking force to the braking drum 2 and a non-operation state in which the braking force is not applied). , Air cylinder) 7 is connected.
[0026]
A drive bush (sliding member) 31 is provided between the inner peripheral surface of the support ring 6 and the outer peripheral surface of the inner peripheral wall 16 and the side wall 30 of the annular casing 3 in order to smoothly rotate the support ring 6. Is interposed (press-fit) over the entire circumferential direction. The drive bush 31 is mainly formed of a fluororesin such as Teflon (registered trademark) or PTFE. As shown in FIG. 9, the drive bush 31 is in contact with objects to be slid (here, the support ring 6 and the annular casing 3). The friction coefficient μ increases when the contact surface pressure Pm is low, and the friction coefficient μ decreases as the contact surface pressure Pm increases.
[0027]
The outer peripheral surface of the inner peripheral wall 16 of the annular casing 3 is subjected to an alumite (registered trademark) treatment to improve wear resistance, so that the support ring 6 can be rotated more smoothly.
[0028]
In this embodiment, the drive bush 31 interposed between the inner peripheral surface of the support ring 6 and the outer peripheral surface of the inner peripheral wall 16 of the annular casing 3 is provided over the entire axial direction of the support ring 6. The first drive bush 31a disposed at one end of the support ring 6 (the left end in the figure), that is, the end connected to the actuator 7, and the second dry bush disposed at the other end. It consists of a bush 31b. On the outer peripheral surface of the inner peripheral wall 16 of the annular casing 3, a hollow portion 32 is formed in the center portion in the axial direction, and the drive bushes 31 a and 31 b are respectively disposed on both axial sides of the hollow portion 32. This rads Rye bush 31a, and 31b, the inner and outer peripheral surfaces and a portion which contacts the inner peripheral wall 16 of the annular casing 3 of the support ring 6, respectively sliding portions 33a, 33b are formed.
[0029]
Here, these drive sashes 31a and 31b have a length in the axial direction Lb of the second drive sash 31b on the other end side rather than an axial length La of the first drive sash 31a on the one end side of the support ring 6. Is formed to be shorter (La> Lb). Therefore, the drive bush 31b, the support ring 6, and the annular casing 3 on the other end side are larger than the area of the sliding portion 33a between the drive bush 31a, the support ring 6 and the annular casing 3 on the one end side of the support ring 6. The area of the sliding portion 33b is smaller. For this reason, assuming that the load applied to the drive bush 31 is the same over the entire region in the axial direction, the contact surface pressure in the sliding portions 33a and 33b is the sliding on the other end side relative to the sliding portion 33a on the one end side. The part 33b becomes larger.
[0030]
However, since the actuator 7 supports the support ring 6 in a cantilever manner as described above, the load applied to the drive bush 31 when the support ring 6 is rotated is the drive bush 31a on the actuator 7 side (one end side). Becomes higher, and the load applied to the drive bush 31b on the other end side becomes smaller.
[0031]
As a result, the contact surface pressure at the sliding portion 33a on the one end side of the support ring 6 and the contact surface pressure at the sliding portion 33b on the other end side are substantially equal to each other, and an appropriate contact surface pressure is ensured. it can. In other words, the load applied to the drive bush 31b on the other end side is smaller than the load applied to the drive bush 31a on the other end side, but the drive bush 31b on the other end side, the support ring 6 and the annular casing 3 This was compensated by reducing the area of the sliding portion 33b (increasing the contact surface pressure) to prevent the contact surface pressure from being insufficient. Accordingly, there is no shortage of contact surface pressure at the sliding portions 33a and 33b between the drive sash 31a and 31b and the support ring 6 and the annular casing 3, and the support ring 6 is increased as the friction coefficient of the drive sash 6 increases and the temperature increases. Can be prevented from malfunctioning.
[0032]
Thus, according to the present invention, the contact surface pressure is reduced by making the area of the sliding portion 33b on the other end side where the load applied to the drive bush 31 is relatively small smaller than the area of the sliding portion 33a on the one end side. Insufficiency is prevented, and malfunction is prevented. Accordingly, the axial lengths La and Lb of the drive bushes 31a and 31b are appropriately set to values that can ensure appropriate contact surface pressures.
[0033]
Although one embodiment of the present invention has been described, various modifications of the present invention are possible. For example, in FIG. 1, it has been described that the recess 32 is formed in the central portion in the axial direction of the outer peripheral surface of the inner peripheral wall 16 of the annular casing 3, but the recess 32 is not necessarily formed. That is, as indicated by a dotted line c in the figure, the outer peripheral surface of the inner peripheral wall 16 of the annular casing 3 may be formed on a straight line.
[0034]
Further, the drive bush 31 has been described as being provided separately on one end side and the other end side of the support ring 6, but the present invention is not limited in this respect, and one drive bush 31 is attached to the shaft of the support ring 6. It may be provided over almost the entire direction. In that case, a recess is formed in the axially central portion of the outer peripheral surface of the inner peripheral wall 16 of the annular casing 3 and / or the inner peripheral surface of the support ring 6. By doing so, sliding portions are formed on both sides in the axial direction of the recess, that is, on one end side and the other end side of the support ring 6. Then, the depression may be formed so that the area of the sliding portion on the other end side is smaller than the area of the sliding portion on the one end side. A plurality of hollow portions are formed in the axial direction, three or more sliding portions are formed in the axial direction of the support ring 6, and the area of the sliding portion located on the other end side is closer to one end side than that. You may make it make it smaller than the area of the sliding part located in this.
[0035]
Next, the embodiment shown in FIG. 2 is a portion where the first and second drive sachets 31a and 31b are located when the first and second drive sachets 31a and 31b are provided at both axial ends of the support ring 6. Recesses 35a and 35b are formed at the center of the outer peripheral surface of the inner peripheral wall 16 of the annular casing 3, respectively. In this embodiment, the sliding portions 33a, 33b, 33c, and 33d between the first and second drive bushes 31a and 31b and the annular casing 3 are formed on both axial sides of the recess portions 35a and 35b, respectively. In this embodiment, the total sliding area is smaller than in the embodiment shown in FIG. 1, so that the contact surface pressure is high, and the friction coefficients of the drive sashes 31a and 31b can be further reduced. Also in this embodiment, the total axial length Lcd (lc + ld) of the sliding portions 33c, 33d between the second drive bush 31b and the annular casing 3 located on the other end side of the support ring 6 is the first end side side. The total length in the axial direction Lab (la + lb) of the sliding portions 33a and 33b between the one drive bush 31a and the annular casing 3 is made shorter (Lab> Lcd).
[0036]
Further, in the sliding portions 33a and 33b between the first drive bush 31a and the inner peripheral wall 16 of the annular casing 3, the axial length lb of the sliding portion 33b located on the other end side is slid on the one end side. The moving portion 33a may be shorter than the axial length la (la> lb). Similarly, in the sliding portions 33c and 33d between the second drive bush 31b and the inner peripheral wall 16 of the annular casing 3, the axial length ld of the sliding portion 33d located on the other end side is located on the one end side. The sliding portion 33c may be shorter than the axial length lc (lc> ld). In addition, you may form a hollow part in the internal peripheral surface of the support ring 6. FIG.
[0037]
Further, it is not always necessary to form the drive bush 31 up to both ends of the support ring 6. As shown in FIG. 3, the drive bush 31b on the other end side is disposed at a predetermined distance h from the other end of the support ring 6. You may make it do.
[0038]
Further, the sliding member 31 is not limited to one or two in the axial direction of the support ring 6, and more sliding members 31 may be provided.
[0039]
In short, the present invention is such that the area of the sliding portion located on the other end side of the support ring 6 is smaller than the sliding portion located on one end side (side to which the actuator 7 is connected). An effect can be obtained.
[0040]
As another embodiment, the steel wear resistance improving member 40 is cast on the outer peripheral surface of the inner peripheral wall 16 of the annular casing 3, that is, the surface facing the drive bushes 31a and 31b, as shown in FIG. It is a thing. According to this embodiment, it is not necessary to perform the above-described anodized (registered trademark) treatment on the outer peripheral surface of the inner peripheral wall 16 of the annular casing 3, and the manufacturing process can be simplified. The wear resistance improving member 40 may be press-fitted into the outer peripheral surface of the inner peripheral wall 16 of the annular casing 3. Further, the shape of the wear resistance improving member 40 can be variously considered as described above. For example, as shown in FIG. 5, you may make it form hollow part 41a, 41b in the center part of the part in which the 1st and 2nd drive bush 31a, 31b is located, respectively.
[0041]
Up to now, it has been described that a plurality of pole pieces 15 are provided in the circumferential direction of the support ring 6. However, the present invention is not limited in this respect, and the pole piece 15 'integrally formed in the circumferential direction as shown in FIG. The present invention can also be applied to an eddy current type speed reducer equipped with
[0042]
The present invention can be applied to any eddy current type speed reducer as long as the support ring 6 is rotated to switch between braking and non-braking.
[0043]
【The invention's effect】
In short, according to the present invention, the contact surface pressure between the sliding member and the support ring and / or the annular casing is optimized, and an excellent effect of preventing the occurrence of malfunction is exhibited.
[Brief description of the drawings]
FIG. 1 is a partially enlarged front sectional view of an eddy current reduction device according to an embodiment of the present invention.
FIG. 2 is a partially enlarged front cross-sectional view of an eddy current reduction device according to another embodiment of the present invention.
FIG. 3 is a partially enlarged front sectional view of an eddy current type speed reducer according to another embodiment of the present invention.
FIG. 4 is a partially enlarged front sectional view of an eddy current type speed reducer according to another embodiment of the present invention.
FIG. 5 is a partially enlarged front cross-sectional view of an eddy current type speed reducer according to another embodiment of the present invention.
FIG. 6 is a partially enlarged cross-sectional view of an eddy current type speed reducer provided with a pole piece integrated in a circumferential direction.
FIG. 7 is a cross-sectional view of the upper half of a conventional eddy current reduction device.
8 (a) is a partial side cross-sectional view showing a state during non-braking in the eddy current type speed reducer of FIG.
(B) It is a partial side sectional view showing the state at the time of braking in the eddy current type reduction gear of FIG.
FIG. 9 is a graph showing a relationship between a contact surface pressure and a friction coefficient in a fluororesin-based sliding member.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rotating shaft 2 Brake drum 3 Annular casing 5 Magnet 6 Support ring 7 Actuator 15 Pole piece 16 Inner peripheral wall 31 Sliding members 33a, 33b, 33c, 33d Sliding part

Claims (6)

A brake drum coupled to the rotating shaft; an annular casing having a pole piece connected to the fixed side inside the brake drum and provided to face the inner peripheral surface of the brake drum; A support ring provided with a plurality of magnets provided in the circumferential direction so as to be rotatable in the circumferential direction and facing the pole piece from the inside, and an inner peripheral surface of the support ring and an inner portion of the annular casing In an eddy current reduction device comprising a drive bush interposed between a peripheral wall and mainly formed of a fluororesin, and an actuator connected to one end side in the axial direction of the support ring and rotating the support ring ,
And the dry bush, the sliding portion between the supporting ring and / or annular casing, as well as a plurality formed in the axial direction, of those sliding portions, located in the axial direction one end side of the upper Symbol support ring An eddy current reduction device in which the area of the sliding portion located on the other axial end side is smaller than the sliding portion . 2. The eddy current according to claim 1, wherein an axial length of the sliding portion located on the other end side in the axial direction of the support ring is shorter than an axial length of the sliding portion located on the one end side in the axial direction. Type speed reducer. The drive bush is formed over substantially the entire area in the axial direction of the support ring, and a recess is formed in the axially central portion of the inner peripheral surface of the support ring and / or the inner peripheral wall of the annular casing, The eddy current reduction device according to claim 1 or 2, wherein sliding portions are formed on both side portions in the axial direction of the hollow portion. The dry bush, the axial end portion of the support ring, an eddy current type reduction gear according to claim 1 or 2, wherein the respectively provided on the other axial end side. On the inner peripheral surface of the support ring and / or the inner peripheral wall of the annular casing, a recess is formed at the center of the portion where each drive bush is located, and a slide portion is provided at each axial end of each drive bush. The eddy current type speed reducer according to claim 4, wherein:   The eddy current type reduction device according to any one of claims 1 to 5, wherein a wear resistance improving member is provided on an outer peripheral surface of an inner peripheral wall of the annular casing.

Images