WO2009066857A1

WO2009066857A1 - Method for manufacturing clutch pulley

Info

Publication number: WO2009066857A1
Application number: PCT/KR2008/004862
Authority: WO
Inventors: Young Guk Kim; Sam Dong Kang
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-11-23
Filing date: 2008-08-21
Publication date: 2009-05-28
Anticipated expiration: 2010-05-23

Abstract

A method for manufacturing a clutch pulley for selectively producing friction with a disc to interrupt a power in an electromagnetic clutch is disclosed. The method includes a first step of performing hot rolling and cold rolling on a base metal of the clutch pulley to form a hub 110, a pulley 120 and a friction wall 130, a second step of performing rough boring and finish boring on an intermediate material formed in the first step to adjust a set specification of the clutch pulley 100, and a third step of forming banana slots 140 on the friction wall 130 machined in the second step by using a non-contact cutting machine. A b-pole clutch is made by minimizing a width of a banana slot formed on the clutch pulley, thereby improving its initial performance.

Description

Description METHOD FOR MANUFACTURING CLUTCH PULLEY

Technical Field

[1] The present invention relates to a banana slot formed on a clutch pulley of an electromagnetic clutch to intersect magnetic flux, and more particularly, to a method of manufacturing a clutch pulley which can minimize a width of a banana slot. Background Art

[2] In general, an electromagnetic clutch is to interrupt transmission of a power generated by an engine or a drive motor to a compressor, and includes a disc to be adhered or detached by the magnetic flux generated from a field coil unit, and a clutch pulley selectively contacting the disc for interrupting the power transmitted to the compressor.

[3] Referring to FIGs. 1 and 2, a clutch pulley 100 includes a hub 110 forming a space for accommodating a field coil unit 200 therein, a pulley 120 provided around the hub 110 and wound with a belt, and a friction wall 130 connecting the hub 110 with the pulley 120 and selectively contacting the disc.

[4] The friction wall 130 is provided with a plurality of banana slots 140 for inducing magnetic flux when an electric current flows in the field core unit 200, and intersecting the magnetic flux. The flow of the magnetic flux is controlled depending upon the number of the banana slots 140 to determine the initial performance and whole performance of the clutch pulley.

[5] If an electric power is applied to the field coil unit 200, the disc 300 is adhered to the friction wall 130 by the magnetic flux that is generated from the field coil unit 200. Thus, the power of the power source (i.e., an engine) connected to the pulley via the belt is transmitted to a driving shaft of the compressor through the hub 110.

[6] By contrast, if the electric power applied to the field coil unit 200 is interrupted, the disc 300 is returned by a resilient force, so that the disc 300 adhered to the friction wall 130 is detached from the friction wall 130. Thus, the power generated by the power source (i.e., an engine) is not transmitted to the driving shaft of the compressor through the hub 110, and is set as an original state.

[7] Explaining the flow of the magnetic flux generated by the clutch pulley 100, when an electric current flows in the field core unit 200, the magnetic flux flows in a direction indicated by an arrow in FIG. 2. In this instance, if the magnetic flux meets an air gap (i.e., atmosphere), the magnetic flux does not flow, and thus flows in adjacent steel.

[8] More specifically, if the magnetic flux flowing along a side of the clutch pulley meets the banana slot 140, as shown in FIG. 2, the magnetic flux flows in the disc 300. If the magnetic flux flowing in the disc 300 meets the banana slot 140, the magnetic flux again flows in the clutch pulley. The above process is repeated four times, which is referred to as a 4-pole clutch.

[9] Consequently, if the friction wall 130 of the clutch pulley 100 is provided not with two rows of banana slots, but with three rows of banana slots 140, and the disc 300 is provided with two rows of banana slots 310, the intersection process in which the magnetic flux alternatively flows in the disc 300 and the banana slot 140 is repeated 6 times, which is referred to as a 6-pole clutch.

[10] In case where the clutch pulley 100 is made in the 6-pole clutch mode, the intersection of the magnetic flux happens two times further in comparison with the 4-pole clutch, which improves the initial performance. However, there is a drawback that it is not possible to form 3 or more rows of banana slots 140 on the friction wall 130 of a small area by an existing press punch.

[11] When the clutch pulley 100 is manufactured by using a press punch, a piecing process of forming the banana slots 140 should be performed between a rough boring process and a finish boring process. As a result, since additional press equipment required for the piecing process is installed, lathe equipment and press equipment are overlapped thereby to increase the installation costs and decrease the productivity.

[12] In the process of piercing the clutch pulley 100, defects such as crack may happen in a base metal due to a compression load of the press equipment. In particular, in case where the magnetic flux is leaked through the defects formed in the base metal, the disc 300 is not completely adhered, and thus it is not possible to execute the operation in cooperation with the interruption of the transmission.

[13] Also, as the width of the banana slot 140 is decreased, the performance of the magnetic flux is increased thereby to improve the adhesion effect of the disc. However, in case where an interval of the banana slots 140 is too short (e.g., up to a half of a thickness of the base metal), a lifetime of the press punch is suddenly shortened, thereby lowering the productivity.

[14] According to the technique of forming the clutch pulley 100 using the press punch, consequently, the interval of the banana slots (i.e., a thickness of a punch) should be at least half of a thickness of the base metal. It is impossible to machine the base metal using the press punch if the interval is short.

[15] Also, when the interval of the banana slot and a slot is up to the thickness of the base metal, an interval between the press punch and a punch becomes narrow, so that the base metal is significantly deformed. The lifespan of the punch is further shortened due to the interference. The frictional surface is so deformed that the deformed surface cannot be corrected by machining.

[16] Therefore, it is impossible to form three rows of banana slots on the friction wall 130, and thus a study on a method of forming the clutch pulley is necessary. Disclosure of Invention

Technical Problem

[17] Referring to FIGs. 3 and 4, it has been proposed to manufacture a 6-pole clutch by forming a friction wall 130 of a relatively increased size in a clutch pulley 100 and punching three rows of banana slots 140 on the friction wall. As the size of the friction wall 130 is increased, it is difficult to set a pulley ratio between the clutch pulley and an engine. Even though the pulley ratio is set by increasing the overhang, an area of the frictional surface is increased to require a high material cost. Also, since additional process such as welding is required, a manufacturing cost is increased. It does not satisfy a small-sized package which is a trend of automobile technology.

[18] In order to solve the drawbacks, a method of reducing a size of the clutch pulley 100 and attaching a separate friction member to the friction wall 130 to increase its friction torque has been proposed. Addition of the friction member causes an advance in the prices of components. Also, a process of attaching the friction member is additionally performed.

[19] In order to decrease the width of the banana slot 140, a method of forming embossed portions on the clutch pulley 100 and filling the embossed portions with non-magnetic material such as copper has been proposed. The process of forming the embossed portions and filling the embossed portions with copper causes the addition in the working time and manufacturing cost. Also, since a working load is increased, it causes an advance in the price of the clutch pulley. Technical Solution

[20] Therefore, an object of the present invention is to solve the problems involved in the prior art, and to provide a method for manufacturing a clutch pulley which can maximize the productivity by simplifying a manufacturing process related to formation of the clutch pulley, and improve an effect of magnetic flux by minimizing a width of a banana slot.

[21] In order to achieve these and other objects, the present invention provides a method for manufacturing a clutch pulley including a hub forming a space to accommodate a field coil unit therein, a pulley provided around a circumference of the hub and wound with a belt, a friction wall for connecting the hub with the pulley, in which a disc is adhered to the friction wall by magnetic flux generated from the field coil unit, and a plurality of banana slots formed on the friction wall to induce the magnetic flux, the method comprising: a first step of performing hot rolling and cold rolling on a base metal of the clutch pulley to form the hub, the pulley and the friction wall; a second step of performing rough boring and finish boring on an intermediate material formed in the first step to adjust a set specification of the clutch pulley; and a third step of forming the banana slots on the friction wall machined in the second step by using a non-contact cutting machine.

Advantageous Effects

[22] With the above description, the method for manufacturing the clutch pulley according to the present invention includes some following advantages. [23] First, since a finish boring and a piercing process are successively performed in the process of manufacturing the clutch pulley, the productivity is increased, and the number of working processes is reduced. Therefore, incidental expenses comprising a machining expense can be reduced. [24] Second, since a compression load is not applied to the clutch pulley during the piercing process, defects to be happening on the clutch pulley can be minimized. Also, since there is no deformation in the clutch pulley, an additional machining process and a cost thereof are not required to correct the deformation. [25] Third, since the compression load is not applied to the clutch pulley during the piercing process, the quality of a final product can be maintained constantly to improve the reliability of a product and an interruption efficiency of transmission. [26] Finally, since a 6-pole clutch is made by minimizing a width of the banana slot, the initial performance of the clutch pulley is improved, and thus the reliability of the product is also improved.

Brief Description of the Drawings [27] The above objects, other features and advantages of the present invention will become more apparent by describing the preferred embodiment thereof with reference to the accompanying drawings, in which:

[28] FIG. 1 is a cross-sectional view of a conventional clutch pulley.

[29] FIG. 2 is a cross-sectional view illustrating a flow of magnetic flux in the clutch pulley in FIG. 1.

[30] FIG. 3 is a cross-sectional view of another conventional clutch pulley.

[31] FIG. 4 is a cross-sectional view illustrating a flow of magnetic flux in the clutch pulley in FIG. 3.

[32] FIG. 5 is a cross-sectional view of a clutch pulley according to a preferred embodiment of the present invention. [33] FIG. 6 is a cross-sectional view illustrating a flow of magnetic flux in the clutch pulley in FIG. 5. [34] FIGs. 7 A and 7B are views explaining the performance of clutch pulleys according to the present invention and the prior art.

Best Mode for Carrying Out the Invention [35] Reference will now be made in detail to preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

[36] FIG. 5 is a cross-sectional view of a clutch pulley according to a preferred embodiment of the present invention, and FIG. 6 is a cross-sectional view illustrating a flow of magnetic flux in the clutch pulley in FIG. 5.

[37] A clutch pulley includes a hub 110 forming a space to accommodate a field coil unit, a pulley 120 provided around a circumference of the hub and wound with a belt, a friction wall 130 for connecting the hub 110 with the pulley 120, a disc being adhered to the friction wall 130 by magnetic flux generated from the field coil unit, and a plurality of banana slots 140 formed on the friction wall 130 to induce the magnetic flux. A method of manufacturing the clutch pulley includes a first step of performing hot rolling and cold rolling on a base metal of the clutch pulley to form the hub 110, the pulley 120 and the friction wall 130, a second step of performing rough boring and finish boring on an intermediate material formed in the first step to adjust a set specification of the clutch pulley 100, and a third step of forming the banana slots 140 on the friction wall 130 machined in the second step by using a non-contact cutting machine.

[38] Although the present invention is described by referring to the hub 110, the pulley

120, the friction wall 130 and the banana slots 140 as components of the clutch pulley 100, the present invention can be applied to any clutch pulley with the banana slots having banana slots 140.

[39] The first step is to cut the base metal of the clutch pulley in a set size and subject the cut base metal to heat treatment. Preferably, hot rolling and cold rolling are repeatedly performed several times, and the hub 110, the pulley 120 and the friction wall 130 which maintain a frame of the clutch pulley 100 are formed to manufacture the intermediate material.

[40] In this instance, the time required for the heat treatment or the numbers of the hot rolling and cold rolling may be depended upon a material, the detailed description thereof being omitted herein.

[41] The second step is to grind the intermediate material formed in the first step to have a wanted size and shape. Preferably rough boring and finish boring are repeated, and inner and outer walls of the friction wall 130 are ground to have an elegant appearance.

[42] The third step is a finish process of forming the banana slots 140 on the material machined in the second step. Preferably, the material is cut to have a width of 0.7 to 2.5 mm by using a water cutter or a laser jet cutter, and the banana slots are formed in a concentric circle on the friction wall.

[43] In the third step, the water jet cutting is performed to pierce the material by using high speed energy that is generated by spraying highly pressurized water onto the friction wall 130. The water jet cutter includes a high-pressure pump for making the water in a high-pressure state, a spray nozzle for spraying the highly pressurized water supplied from the high-pressure pump, and a connecting pipe for connecting the high- pressure pump with the spray nozzle.

[44] Also, the laser jet cutting is performed to pierce the material by using thermal shock that is generated by repeatedly carrying out rapid heating and quenching on the friction wall 130. The laser jet cutter includes a laser oscillator for generating a laser beam, and a cooler for spraying a coolant onto a condense surface rapidly heated by the laser beam.

[45] Although this embodiment is described by referring to the water cutting method and the laser jet cutting method as a non-contact cutting method, the present invention can be applied to any precision machining method such as plasma cutting.

[46] In the process of forming the banana slots 140, a circular induction groove for inducing the magnetic flux or a circular blocking groove for preventing leakage of the magnetic flux is added to maximize a magnetic induction efficiency. Also, the magnetic induction efficiency can be maximized by properly selecting arrangement of the banana slots.

[47] A post-treatment performed after the third process, such as an adhering process, a brushing process of finishing a surface of the clutch pulley, or a particle removing process of removing particles, will be not described herein.

[48] The operation of the clutch pulley according to the present invention will now be described.

[49] First of all, the magnetic flux generated by the field core unit 200 flows along the clutch pulley 100 in a direction indicated by an arrow in FIG. 6. In this instance, if the magnetic flux meets the banana slot 140, the magnetic flux does not flow, and thus flows in the disc 300 adhered to the friction wall 130.

[50] Then, if the magnetic flux flowing along the disc 300 meets another banana slot 140 of the disc, the magnetic flux flows in the friction wall 130 adhered to the disc 300. The above process is repeated six times, which makes a 6-pole clutch.

[51] Referring to FIG. 7 A, in which the banana slots having a diameter of 3 mm are formed by using a conventional machining method, and FIG. 7B, in which the banana slots having a diameter of 1.2 mm are formed by using the present invention, the performance of clutch pulleys will now be compared.

[52] In this instance, initial conditions of an electromagnetic analysis system comprise an air gap of 0.050 mm, a voltage of 12 voltages, and the numbers of turns is 325.

[53] As shown in FIG. 7A, the performance of the clutch pulley according to the prior art comprises magnetic force of 2153.126 N, torque of 2.678 kgf-m, and flux linkage of 0.634 Wb. [54] As shown in FIG. 7B, the performance of the clutch pulley according to the present invention comprises magnetic force of 2308.082 N, torque of 2.876 kgf-m, and flux linkage of 0.704 Wb.

[55] Consequently, in case of machining the 6-pole clutch using the non-contact machining method, the magnetic force, since the torque and the flux linkage are further improved, as compared with the prior art, the adhesion and detachment of the disc 300 is smoothly performed to improve the interruption efficiency of transmission.

[56] While the present invention has been described and illustrated herein with reference to the preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made therein without departing from the spirit and scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention that come within the scope of the appended claims and their equivalents.

[57]

[58]

Claims

[1] A method for manufacturing a clutch pulley including a hub 110 forming a space to accommodate a field coil unit therein, a pulley 120 provided around a circumference of the hub and wound with a belt, a friction wall 130 for connecting the hub 110 with the pulley 120, in which a disc is adhered to the friction wall 130 by magnetic flux generated from the field coil unit, and a plurality of banana slots 140 formed on the friction wall 130 to induce the magnetic flux, the method comprising: a first step of performing hot rolling and cold rolling on a base metal of the clutch pulley to form the hub 110, the pulley 120 and the friction wall 130; a second step of performing rough boring and finish boring on an intermediate material formed in the first step to adjust a set specification of the clutch pulley 100; and a third step of forming the banana slots 140 on the friction wall 130 machined in the second step by using a non-contact cutting machine.

[2] The method as claimed in claim 1, wherein the non-contact cutting machine comprises a water jet cutter and a laser jet cutter.