WO2017118993A1

WO2017118993A1 - Starter for an internal combustion engine provided with a conical spring

Info

Publication number: WO2017118993A1
Application number: PCT/IN2016/050001
Authority: WO
Inventors: Muruganandam RADHAKRISHNAN; Thulsirajan GANESAN; Sathishkumar MANOHARAN; Sarankumar RAMAKRISHNAN
Original assignee: Comstar Automotive Technologies Pvt Ltd
Priority date: 2016-01-05
Filing date: 2016-01-05
Publication date: 2017-07-13

Abstract

A starter motor, the pinion, which is rotated by torque of an electric motor, is slid axially by the plunger of an electromagnetic switch and is pushed against the engine ring gear by a conical spring, which allows employment of a small electromagnetic switch. Further, in an electromagnetic switch in which the plunger confronted coaxially with the stationary iron core slidably supporting a rod with a movable contact is moved towards the stationary iron core by electromagnetic force, a conical spring is interposed between the plunger and the stationary iron core in such a manner that the spring is substantially coaxial with the plunger and the iron core, so that the playing of the rod is prevented.

Description

STARTER FOR AN INTERNAL COMBUSTION ENGINE

PROVIDED WITH A CONICAL SPRING

FIELD OF THE INVENTION

[001] The present invention generally relates to starters for a motor vehicle, and particularly relates to an improvement of spring arrangement in the starter motor.

BACKGROUND OF THE INVENTION

[002] A conventional starter for starting a vehicle engine is designed as shown in FIG. 1

[003] More specifically, the conventional starter device 1, as shown in FIG. 1, comprises: a DC motor 2; an over-running clutch 4 slidably mounted on the output rotary shaft 3 of the motor; an electromagnetic switch 6 provided beside the DC motor 2; and a shift lever 10 having one end engaged with a hook 8 coupled to the plunger 7 of the electromagnetic switch 6 and the other end engaged with the cylindrical rear end portion 9 of the over-running clutch 4 so as to slide the over-running clutch 4 on the output rotary shaft 3.

[004] The electromagnetic switch 6 for operating the shift lever 10 has a cylindrical outer frame 11 which has a wall 1 1a at one end. The aforementioned plunger 7 is inserted into the end wall 1 la. A stationary iron core 12 is disposed at the other end of the outer frame 1 1 in such a manner as to confront with the plunger 7. The iron core 12 has an end wall which is fixedly fitted in the rear end portion of the outer frame 1 1, thus forming a frame together with the outer frame 1 1. A coil bobbin 13 is accommodated in the frame thus formed. An exciting coil 14 is wound on the coil bobbin 13. A return spring 15 is interposed between the iron core 12 and the plunger 7. The iron core 12 has a central through-hole, into which a rod 16 is slidably inserted in such a manner that its one end portion (or front end portion) is extended from the iron core 12 towards the plunger 7. The other end portion (or rear end portion) of the rod 16 supports a movable contact 17.

[005] The starter further comprises: a carrier rod 18 for returning the rod to a predetermined position; a cap 19 made of resin; and a terminal bolt 20 embedded in the cap 19 so that its inner end serves as a stationary contact with which the movable contact 17 is brought into contact. A magnet 25 connected at the base of the DC motor 2 and a brush box assembly 26 placed in the rear end of the starter motor as protecting device.

[006] The plunger 7 is inserted into the central opening formed in the end wall 11a of the outer frame 11, and it is moved along the central axis of the coil bobbin 13 towards the iron core 12. The plunger 7 has a recess which is opened axially outward. The above-described connecting rod 8 is in the form of a piston and has a flange at the rear end. The connecting rod 8 is slidably inserted into the recess of the plunger 7 and is extended outside passing through the central hole that is formed in a holder 21, which closes the open end of the recess of the plunger 7. The outer end portion of the connecting rod 8 is engaged with the upper end of the shift lever 10. Inside the recess of the plunger 7, a cylindrically coiled spring, namely, a compression spring 22 is interposed between the holder 21 and the flange of connecting rod 8. [007] The operation of the conventional starter thus constructed will be described in brief.

[008] When the key switch of the vehicle is turned on, the exciting coil 14 of the electro-magnetic switch 6 is energized so that the plunger 7 is moved towards the iron core 12. As a result, the shift lever 10 is turned, whereby the over-running clutch 4 and the pinion 5 integral with the clutch inner portion are slid on the output rotary shaft 3. In this operation, when the pinion 5 abuts against the side of the engine ring gear, the turning of the shift lever 10 is stopped while the plunger 7 continues to move towards the iron core, the compression spring 22 is compressed, so that the pinion is pushed against the engine ring gear through the shift lever 10.

[009] As the plunger 7 pushes the rod, the movable contact 17 is brought into contact with the stationary contact, so that the DC motor 2 is energized. As a result, as soon as the pinion 5 is rotated, it is engaged with the engine ring gear by the elastic force of the compression spring 22.

OBJECTS OF THE INVENTION

[010] The present invention overcomes the shortcomings associated with the background art and achieves other advantages not realized by the background art.

[011] The principal object of the present invention is to provide conical spring arrangement in starter motor to work on change of mind conditions viz., key start, early engagement and back crank engagement. [012] Another object of the present invention about conical spring arrangement in starter motor that is simply adaptable with the existing starter design without much modification therein.

SUMMARY OF THE INVENTION

[013] To solve the above-described problems, the present invention has been devised, an object of the invention is to provide a starter in which with a small electromagnetic switch, the plunger can be moved against a compression conical spring having a certain elastic force.

[014] The present invention have been achieved by the provision of a starter in which a pinion, which is rotated by torque of an electric motor, is slid axially by the plunger of an electromagnetic switch, and is pushed against an engine ring gear by a compression spring before rotated; in which, according to the invention, said compression spring is a conically coiled spring.

[015] The foregoing object and other objects of the invention have been achieved by the provision of an electromagnetic attracting unit in which a movable iron core confronted coaxially with a stationary iron core is moved towards the stationary iron core by electromagnetic force, which comprises: a conically coiled spring interposed between the stationary iron core and the movable iron core in such a manner that the spring is substantially coaxial with the stationary iron core and the movable iron core. [016] When, in the starter of the invention, the plunger of the electromagnetic switch is moved to slide the pinion along the axis, the conically coiled spring is compressed to push the pinion against the engine ring gear. In this operation, the conically coiled spring is deflected (compressed) beginning with its end larger in diameter, thus showing a spring characteristic similar to a plunger attracting force characteristic. Therefore, the force of attracting the plunger will never become in balance with the force of deflecting the conically coiled spring.

BRIEF DESCRIPTION OF THE DRAWINGS:

[017] The present invention will be better understood fully from the detailed description that is given herein below with reference to the accompanying drawings of the preferred embodiments of the present invention, which, however, should not be deemed to be a limitation to the invention to the specific embodiments, but, are for the purpose of explanation and understanding only.

In the drawings:

[018] FIG. 1 is a sectional view showing a conventional starter motor.

[019] FIG. 2 is a drive assembly of a conventional starter motor.

[020] FIG. 3 is a characteristic diagram indicating wear performance of a conventional starter motor.

[021] FIG. 4 is a sectional view showing conical spring arrangement in starter motor according to this invention.

[022] FIG. 5 is a drive assembly in a starter motor with conical spring. [023] FIG. 6 is exploded view of drive assembly in a starter motor with conical spring.

[024] FIG. 7 is a characteristic diagram indicating wear performance of a starter motor with conical spring.

DETAILED DESCRIPTION OF THE INVENTION

[025] While this invention is susceptible of embodiments in many different forms, the detailed description of the preferred embodiments with reference to the corresponding drawings shown herein below are to be understood that the present disclosure shall be deemed as an example of the principles of the invention and not intended to limit the invention to the specific embodiments shown and described. In the description below, like reference numerals are used to describe the same, similar or corresponding parts in the several views of FIG 4 - 7.

[026] Referring to FIG. 2, the drive assembly of a conventional starter motor wherein the pinion (1) attached with the drive cup (2) which is intend supported with drive barrel (3). Because of this arrangement with in few cycles the pinion starts wearing off as well as the flange and tooth. This wearing effect, affects the performance and the life span of the starter motor. The characteristic diagram indicating wear performance of a conventional starter motor is shown in FIG.3 wherein the line Rl refers to the ring gear wear which initially starts from zero and moving gradually to the peak within few cycles and also the PI which refers to the pinion wear also reacting the same way as the ring gear wear. In this conventional method of starter won't support the change of mind conditions such as key start, early engagement and back crank engagement. And also load effect is very high which in turn creates a very high initial noise, the wear patterns also in the peak by using this conventional method of starters. Within few cycles of starts the ring gear, pinion and other rotating parts starts degrading, to overcome the above mentioned concerns the new conical spring arrangement introduced in the starter motor.

[027] The conical spring arrangement in starter device, as shown in FIG. 4, comprises: a DC motor; a conical spring 104 slidably mounted on the output rotary shaft of the motor; an electromagnetic switch 6 provided beside the DC motor; and a shift lever 10 having one end engaged with a hook 8 coupled to the plunger 7 of the electromagnetic switch 6 and the other end engaged with the cylindrical rear end portion 9 of the conical spring 104 so as to slide the conical spring on the output rotary shaft.

[028] The electromagnetic switch 6 for operating the shift lever 10 has a cylindrical outer frame 11 which has a wall 11a at one end. The aforementioned plunger 7 is inserted into the end wall 1 la. A stationary iron core 12 is disposed at the other end of the outer frame 1 1 in such a manner as to confront with the plunger 7. The iron core 12 has an end wall which is fixedly fitted in the rear end portion of the outer frame 1 1, thus forming a frame together with the outer frame 1 1. A coil bobbin 13 is accommodated in the frame thus formed. An exciting coil 14 is wound on the coil bobbin 13. A return spring 15 is interposed between the iron core 12 and the plunger 7. The iron core 12 has a central through-hole, into which a rod 16 is slidably inserted in such a manner that its one end portion (or front end portion) is extended from the iron core 12 towards the plunger 7. The other end portion (or rear end portion) of the rod 16 supports a movable contact 17.

[029] The starter further comprises: a carrier rod 18 for returning the rod to a predetermined position; a cap 19 made of resin; and a terminal bolt 20 embedded in the cap 19 so that its inner end serves as a stationary contact with which the movable contact 17 is brought into contact. A magnet 25 connected at the base of the DC motor and a brush box assembly 26 placed in the rear end of the starter motor as protecting device.

[030] The plunger 7 is inserted into the central opening formed in the end wall 11a of the outer frame 11, and it is moved along the central axis of the coil bobbin 13 towards the iron core 12. The plunger 7 has a recess which is opened axially outward. The above-described connecting rod 8 is in the form of a piston and has a flange at the rear end. The connecting rod 8 is slidably inserted into the recess of the plunger 7 and is extended outside passing through the central hole that is formed in a holder 21, which closes the open end of the recess of the plunger 7. The outer end portion of the connecting rod 8 is engaged with the upper end of the shift lever 10. Inside the recess of the plunger 7, a cylindrically coiled spring, namely, a compression spring 22 is interposed between the holder 21 and the flange of connecting rod 8.

[031] The operation of the conventional starter thus constructed will be described in brief. When the key switch of the vehicle is turned on, the exciting coil 14 of the electro-magnetic switch 6 is energized so that the plunger 7 is moved towards the iron core 12. As a result, the shift lever 10 is turned, whereby the over-running clutch 4 and the pinion 103 integral with the clutch inner portion are slid on the output rotary shaft. In this operation, when the pinion 103 abuts against the side of the engine ring gear, the turning of the shift lever 10 is stopped while the plunger 7 continues to move towards the iron core, the compression spring 22 is compressed, so that the pinion is pushed against the engine ring gear through the shift lever 10. As the plunger 7 pushes the rod, the movable contact 17 is brought into contact with the stationary contact, so that the DC motor is energized. As a result, as soon as the pinion 103 is rotated, it is engaged with the engine ring gear by the elastic force of the compression spring 22.

[032] Referring to FIG. 5, a drive assembly section of a starter motor with conical spring arrangement. A drive cup 7 shielding the whole drive assembly, there is a carrier rod 1 placed at centre of the drive assembly which connects the whole set up and retainer cup 2 placed on the carrier rod for tightening the set up. A pinion 3 were placed which engaged with the other side of the starter assembly. And a novel aspects is conical spring 4 placed in between the pinion and the spring retainer cup 5. Drive barrel 5 placed alongside of the drive cup for the further protection of the assembly.

[033] By this type of arrangement the length of the motor is reduced drastically, the spring absorbs the entire load while starting and release the same to the pinion gradually. This methodology reduces the load effect and the initial noise in the engine while starting. The wear patterns like ring gear and pinion gear are proportionally reduce to an extent by which the starter life time and the cycle increases accordingly.

[034] Referring to FIG. 6, exploded view of drive assembly in a starter motor with conical spring 4. This arrangement clearly explains about conical spring arrangement in a detailed manner, wherein drive barrel 6 internally connected with carrier rod and the spring retainer cup 5 also placed on the carrier rod. The retainer cup 2 arranged as permanent seal above side of the entire setup and fixed with a jump ring 8 which won't allow any of the parts to move internally. The conical spring 4 is placed between the spring retainer cup 5 and the pinion 3 and take the entire pressure from either side and release the same gradually which protect the entire set up from damage and also increase the number of cycles.

[035] According to FIG. 7, the teeth wear performance projected in terms of ring gear and pinion across their cycles. This new method of conical spring arrangement in starter motor adhere to the change of mind conditions as well as it reduces the load effect, initial noise in the engine and also the wear in the patterns like ring gear and pinion. Through this means of arrangement the life cycle of the starter increases, the characteristic diagram shows the R2 and P2 were much in the bottom comparing to its Rl and PI performance in the conventional method starter which represented in FIG. 3. Hence, the preferred embodiment disclosed in the foregoing description should not construed as a limitation to the scope of the present invention.

[036] It will be readily appreciated by those skilled in the art that modifications may be made to the invention without departing from the concepts disclosed in the foregoing description. Accordingly, the preferred embodiments described in detail herein are illustrative only and are not limiting to the scope of the invention, which is to be given the full extent of the appended claims.

Claims

1) A starter, comprising a pinion; an electric motor for generating a torque to rotate said pinion; an electromagnetic switch having a plunger, said electrical contacts, said plunger being movable, by virtue of a magnetic attraction force, so as to slide said pinion in an axial direction thereof; and a conical spring, providing a force in opposition to said magnetic attraction force, for pushing said pinion into a desired position against an engine ring gear before said pinion is rotated, said spring comprising a conical spring, the characteristics of said spring being preselected so as to maintain a force due to said spring that is always less than said magnetic attraction force so as to insure that said plunger can continue moving, after said pinion is placed in said desired position, in order to actuate said electrical contacts.

2) A starter motor according to claim 1 : wherein said conical spring is compressed beginning with an end thereof larger in diameter.

3) A starter motor according to claim 1 : wherein said conical spring is provided in said plunger.

4) A starter motor according to claim 1 further comprising a shift lever having one end thereof which is connected directly to said plunger and the other end thereof which is connected to said pinion, and a fulcrum portion on which said conical spring is provided, said fulcrum portion being turned until said pinion abuts against said engine ring gear and thereafter moved backwardly so that said conical spring is deflected.

5) A starter motor according to claim 1 : further comprising a shift lever having one end thereof which is connected to said plunger and the other end thereof which is connected to said pinion through said conical spring.