MXPA98009466A - Engine braking system used by the alternate stator - Google Patents

Abstract

The present invention relates to a motor having a set of stator coils, which are connected to supply power to power accessories, and current to a battery charger, when the motor is running. When the ignition is turned off, a braking switch is closed which short-circuits the coils. The large amount of current resulting in the stator coils produces a torque for braking on the motor shaft, which quickly stops the shaft and any attachment attached to the motor.

Description

ENGINE STOP SYSTEM USED FROM THE ALTERNATOR STATOR FIELD OF THE INVENTION The present invention relates to implements driven by a motor, and more particularly to the braking of implements such as mower blades, when the motor has.

BACKGROUND OF THE INVENTION Implements for farms, meadows and gardens, such as mowers, motorized sweepers, aerators, or the like, are usually driven directly from the PTO of a gasoline engine or indirectly through a clutch. It has become increasingly common, on larger equipment, to use an electrically controlled clutch which also includes a brake mechanism.

When the clutch is actuated to uncouple the tool that is running, such as a mower blade, from the motor, the REF. : 28929 brake mechanism engages to decelerate the tool in operation and stop it quickly. These clutch and brake mechanisms are like those shown, for example, in U.S. Patent No. 3,773,156; No. 4,181,206; No. 4,585,115; and No. 4,570,766. For smaller equipment such as lawn mowers, also, the use of separate clutch and brake mechanisms has been proposed, as described in US Patent No. 3,111,800, but in general those structures are considered too expensive. Therefore, in most cases, the motor simply stops when the ignition circuit is interrupted, as described for example in U.S. Patent Nos. 4,236,494 and 4,885,903.

BRIEF DESCRIPTION OF THE INVENTION The present invention consists of a reliable and inexpensive brake to quickly stop a motor shaft and any attachment attached thereto, when the engine is stopped. More specifically, it includes a set of permanent magnets that are mounted to rotate by the action of the shaft; a winding of the stator, mounted to the motor, to interact with the rotating magnets and produce a current; and a braking switch connected to the stator winding and which can be operated when the motor is turned off, to short-circuit the stator winding. The large amount of current that occurs when the stator winding short-circuits, interacts with the magnetic field of the rotating magnets to produce a torque, braking, on the motor shaft, which quickly stops the same and any implement that is attached to it. A general objective of the invention is to provide a reliable brake for an implement driven by a motor. There are very few mechanical parts that can be spent. Iruppers are highly reliable devices that are easy to replace if they malfunction. The permanent magnets and the stator winding form an alternator which is also a very reliable device. "" Another object of the invention is to provide an economic brake. The alternator is a necessary component of the engine, to provide current for various purposes, while the engine is running. The present invention makes use of this same structure, with the addition of a braking switch, to produce a torque, of braking, when the engine is turned off. Composite mechanical or electrical structures are not required. From the following description of the invention will emerge the foregoing aims and advantages, as well as other additional objects and advantages. In the description reference is made to the accompanying drawings which will form part thereof, and in which, by way of illustration, a preferred embodiment of the invention is shown, however that embodiment does not necessarily represent the full scope of the invention, and therefore, reference is made herein to the claims to interpret the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an elevation view, with parts in section, of an engine employing the present invention; Figure 2 is an electrical diagram, schematic, of a circuit used with the engine of Figure 1, to implement the preferred embodiment of the invention; Y Figure 3 is a graphic illustration of the braking system provided by the present invention.

DESCRIPTION OF THE PREFERRED MODALITY Referring particularly to Figure 1, an internal combustion engine 10 rotates a shaft 12 that can be engaged to operate an implement such as the blades of a mower (not shown in the drawings). A flywheel 14 is mounted to the shaft 12 and supports a ring of permanent magnets 16 that surrounds the shaft 12 and which is oriented radially inwardly. A stator assembly 18 is mounted to the motor 10 and is positioned in the same plane as that of the magnets 16. The stator assembly or assembly includes eighteen separate coils 20 which are arranged in a circle about axis 12 and spaced apart. equidistantly. The coils 20 are connected in series and form a single winding of 1 stator. When the motor 10 is running, the shaft 12 rotates the magnets 16 around the stationary stator assembly 18. In the stator winding an alternating current (AC) is induced due to its interaction with the changing magnetic field produced by the magnets. As is well known in the art, this same interaction that generates the current in the winding of the stator also produces a torque on the axis 12 which opposes its rotational movement.The larger the current generated the greater is the opposite torque Referring particularly to Figure 2, three conductors 26, 28 and 30 are connected to the stator winding The first eleven coils 20 of the stator, connected in series, are connected between the conductors 28 and 30, and the the last five coils 20 of the stator, connected in series, are connected between the conductors 26 and 28. The conductor 26 is connected to the earth circuit and the conductor 28 provides Alternating current (AC) for the implement, in a terminal 32. The conductor 28 is also connected through a diode 34 to provide direct current (DC) for a battery charger, in terminal 36. During normal operation of the In this case, the five coils 20 (marked 14-18 in Figure 2) produce, therefore, an alternating current which feeds such things as illumination, and provides a charging current for the implement battery. The third conductor 30 of the stator winding is connected to the ground circuit through a braking switch 40. When the braking circuit 40 is closed, both ends of the stator winding are connected to the ground of the circuit, and the winding It is shorted. As a result an immense current flows through the winding of the stator and to the motor shaft 12 a corresponding high torque, braking is applied. During normal operation of the motor the braking switch 40 opens as shown in Figure 2 and no current is produced by the eleven coils 20 of the stator connected between the conductors 28 and 30 (coils marked 1-11 in Figure 2). The braking switch 40 can be part of the ignition system of the engine, indicated in general with the number 42, and can, for example, be operated mechanically together with an ignition switch 44. When the ignition switch 44 is closed to make operating the engine 10, the braking switch 40 is opened in such a way that torque is not produced for braking. However, when the ignition switch 44 is opened, the braking switch 40 is closed and a torque is produced for braking due to the current flow of the stator winding. This quickly stops the motor shaft 12. As a result, any implement is also stopped, for example the blades of a mower, which are driven by the shaft 12. With particular reference to Figure 3, when applied to a gardening tractor, the present invention reduced the braking time for its rotating blades / by approximately 15 hours. %. The curve 60 indicates the braking time as a function of the engine speed, for the gardening tractor, without making use of the present invention. Curve 62 indicates the braking time for the same gardening tractor "when the preferred embodiment of the invention is employed." The present invention maintains the braking time below 5 seconds at an engine speed of 3. 300 rpm, and this same limit, of 5 seconds, exceeds an engine speed of 2, 700 rpm when the invention is not used.It is noted that in relation to this date, the best method known by the applicant to carry out the cited invention, is the one that is clear from the present description of the invention Having described the invention as above, it is claimed as property contained in the following:

Claims (7)

1. In an engine that rotates an axis coupled to an implement, the improvement characterized in that it comprises: a set of permanent magnets mounted to rotate by the action of the shaft; a stator winding mounted to the motor and placed adjacent the set of permanent magnets, so that a current is induced in the stator winding when the shaft rotates; and a braking switch connected to the stator winding and which can operate when the motor is turned off, to short-circuit the stator winding and produce a large current in it, which interacts with a magnetic field produced by the permanent magnets for produce a torque on the shaft, which stops the shaft and the implement attached to it.

2. The improvement, according to claim 1, characterized in that the winding of the stator supplies current to the accesses associated with the motor, when the motor is running.

3. The improvement according to claim 1, characterized in that the winding of the stator is composed of a set of stator coils, placed around the motor shaft.

4. The improvement according to claim 3, characterized in that one or more "of the stator coils supply current to the accessories associated with the motor, when the motor is running.

5. The improvement according to claim 3, characterized in that the coils of the assembly are connected in series.

6. The improvement according to claim 1, characterized in that one end of the winding of the stator is connected to the ground pole of the circuit and the other end of the stator winding is connected to the ground pole of the circuit, through the circuit breaker. braking

7. The improvement according to claim 1, characterized in that the braking switch is operated by an ignition system of the engine.