JPH032023Y2 - - Google Patents

Description

[Detailed explanation of the idea]

"Industrial Application Field" This idea applies braking by bringing the armature into pressure contact with the circumferential surface of the braking drum by the force of a spring, either directly or through a friction material, and by applying electromagnetic attraction to the armature. This invention relates to a drum-type electromagnetic brake of non-excitation type that releases braking by attracting it against the force of a spring. "Prior Art" Conventional electromagnetic brakes of this type include those shown in FIGS. 5 and 6. FIG. 5 is a longitudinal sectional view, and FIG. 6 is a side view,
A brake drum 1 has an inner circumferential surface of an outer cylindrical portion as a braking surface, and is fitted onto a braked shaft (not shown) at a hub portion which is an inner cylindrical portion. 2 is a ring-shaped electromagnetic portion, and a yoke 3 opens toward the outer circumference;
It is composed of a coil 4 housed in a recess of the yoke, and is fixed to a device using the brake using a screw hole 5 provided on one side. Reference numeral 6 denotes a plurality of armatures each having an inner circumferential surface facing the magnetic pole surface, which is also the outer circumferential surface of the yoke 3, with an air gap in between. It is rotatable in the radial direction as a support shaft. The support plates 7, 7 are fixed to both sides of the yoke 3. A braking spring 8 is inserted into a hole provided in a radial direction in the magnetic pole portion of the yoke 3 in correspondence with each armature 6, and a coil spring is used to press the armature 6 toward the inner circumferential surface of the drum 1. Reference numeral 9 denotes a friction member fixed to the outer periphery of the tip of the armature 6. In the above configuration, when no current is supplied to the coil 4, each armature 6 is opened outward by the force of each brake spring 8, and this armature is pressed against the inner circumferential surface of the drum 1 via the friction member 9. Braking is applied to a braked shaft (not shown) connected to the drum through this drum. When current is supplied to the drum 4 in this state, magnetic flux flows through the path shown by the broken line, and each armature 6 is attracted toward the magnetic pole of the yoke 1 against the force of the spring 8, and is separated from the inner circumferential surface of the drum 1, and the braking on the braked shaft is released. ``Problems to be solved by the invention'' The conventional electromagnetic brake described above is used for braking when a load that is operated intermittently is quickly stopped by controlling the power supply of the drive motor on and off. Naturally, during braking, it is necessary to instantaneously stop the rotation of the braked shaft, which is the load shaft, and to do so, it is necessary to increase the force of the spring 8 to increase the braking force. On the other hand, in order to suppress the excitation current as much as possible in terms of efficiency, and to avoid increasing the size of the device, the excitation attraction force and braking spring force are set so that they are approximately balanced, resulting in manufacturing errors. Due to variations in the electromagnetic suction force, changes in temperature, slight fluctuations in the power supply, etc., the suction force was insufficient, causing problems such as the armature not being suctioned. This invention was developed in view of these circumstances, and the purpose is to increase the braking release force that resists the force of the braking spring without increasing the excitation current or increasing the size of the device. "Means for Solving the Problems" This invention is characterized by providing the armature with a notch near its support point to restrict the passage of magnetic flux through this part. "Effect" When current is supplied to the coil, the magnetic flux flowing through the armature avoids this part due to the magnetic saturation phenomenon at the base end of the armature due to the presence of the notch, and concentrates more towards the free end of the armature. As a result, the brake release force acting against the brake spring increases. "Embodiment" An embodiment of this invention will be described below with reference to FIGS. 1 to 4. Figures 1 and 2 show a side view and a plan view of a portion, and Figures 3 and 4 are a sectional view and a plan view of only the armature. Reference numeral 11 shows the armature, and only one armature is shown in the drawing. The central part of the base end, which is the pivot point of each armature, is cut out with a notch 12 left on both sides, and the dimensions of this part are as shown in Figures 3 and 4. The length of 11 is L, and its thickness is
When C _S is the length (depth) of the notch 12, _S is the width of the remaining portion on both sides of the notch 12, and d is the length of the notch, _S is the width of the remaining portion, and is the plate thickness of the armature. The respective dimensional ratios of C _S to the armature length L are 0.44, 0.07, and 0.07. The other parts have the same structure as the conventional one shown in Figs. 5 and 6, so the same reference numerals are given to the parts corresponding to these parts, and the explanation thereof will be omitted. . The embodiment of this invention is constructed in this manner. Next, to explain its operation, when an electromagnetic attraction force is applied to the armature 11 in FIG. If the free end is θ2 and the electromagnetic attraction force acting on each point θ from θ1 to θ2 is Fθ, then the torque T0 acting on the armature is expressed as T0=∫〓 ² 〓 ₁ F(θ)(θ)dθ Ru. Therefore, in order to maximize the torque T0, it is sufficient to push the magnetic flux passing through the armature toward the θ2 side, which is the tip of the armature, and to increase Fθ and θ. In this regard, as in the embodiment, by providing a notch 12 having a width and depth to an extent that does not reduce the amount of total magnetic flux passing through the armature near the base end of the armature, the pivot point of the armature, A magnetic saturation phenomenon occurs in this portion, and the magnetic flux passing through the armature is concentrated on the tip θ2 side, which is the free end, and the above Fθ and θ become large, and as a result, the torque acting on the armature increases. This means that, compared to conventional armatures without cutouts, the force resisting the force of the damping spring for the same excitation current and therefore the total number of magnetic fluxes passing through the armature is increased. In addition, the braking spring at the time of armature suction compared to the conventional product at the respective set dimensional ratios of the length _S of the notch 12, the width d of the remaining portion on both sides of the notch 12, and the plate thickness C _S of the armature to the total armature length. The following table shows the experimental results of the suction force (pressure force) ratio against .

[Table] From the above, it is clear that the suction force on the armature (pressure force on the brake spring) increases compared to the conventional product, and the effect is especially remarkable in each dimension ratio of the above-mentioned notch of the present invention. The characteristics will be improved by 40%. "Effect of the invention" As explained above, according to this invention, a notch is provided near this pivot point of the armature,
Due to the presence of this notch, the magnetic flux passing through the armature is concentrated on the tip side of the armature, and by specifying the dimensions of the notch, the effect is maximized, so the excitation current can be increased. , it is possible to maximize the attraction force (braking release force) to the armature without increasing the size of the electromagnetic brake, and it is possible to prevent variations in electromagnetic attraction force due to manufacturing errors, changes in temperature, fluctuations in power supply voltage, etc. The brake release function can always be exerted regardless of the

[Brief explanation of drawings]

1 and 2 are a partial side view and a plan view showing an embodiment of this invention, FIGS. 3 and 4 are a sectional view and a plan view of an armature to explain the operation of this invention, and FIG. 6 are a longitudinal sectional view and a side view showing a conventional electromagnetic brake. 1...Drum, 2...Electromagnet section, 6, 11...
Armature, 8...Brake spring, 12...Notch.

Claims (1)

[Scope of utility model registration request] An armature is provided between the magnetic pole surface of the electromagnet part and the cylindrical part of the drum and supported at one end so as to be rotatable in the radial direction, and this armature is pressed against the drum by the force of a braking spring. This is an electromagnetic brake that applies braking to a braked object and releases the brake by the attractive force of an electromagnet that resists the force of the brake spring, and has a notch that leaves residual parts on both sides near the support point of the armature. established a department,
The length _S of this notch, the width d of the remaining portion on the sides of this notch, and the size ratio of the plate thickness C _S of the armature to the total length L of the armature are 0.44, respectively.
A non-excitation type drum type electromagnetic brake characterized by setting the values to 0.07 and 0.07.