US2021822A - Time delay device for automatic switches - Google Patents

Description

Nov. 19, 1935. M. P. WHITNEY 2,021,822

TIME DELAY DEVICE FOR AUTOMATIC SWITCHES Filed April 12, 1930 3 Sheets-Sheet l lNVENTOR Maurice P. Whi tn c ATTORNEY Nov. 19, 1935. p w rr 2,021,822

TIME DELAY DEVICE FOR AUTOMATIC SWITCHES Filed April 12, 1930 3 Sheets-Sheet 2 31 a 1 30 13 j 00 E 99 Q. 1 39 2g $$$$$$$$i 8 .;.u.......-nna

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TTORNEY NOV. 19, 1935. M, p w E 2,021,822

TIME DELAY DEVICE FOR AUTOMATIC SWITCHES Filed April 12, 1930 3 SheetsSheet 3 To IGNITION 4 ynmwnw /5.2 Fig.

INVENTOR Maurice R Wh 'Liney A TTORNE V Patented Nov. 19, 1935 TIltiE DELAY DEVICE FOR AUTOMATIC SWITCHES Maurice P. Whitney, Elmira, N. Y., assignor to Eclipse Machine Company, Elmira, N. Y., a corporation of New York Application April 12, 1930, Serial No. 443,833

4Ciaims.

This invention relates to a novel time delay device for an automatic switch and particularly to a means for delaying the closing of an automatic switch for starting mechanism.

One object of the device is the provision of a novel time delay for automatic switches which is reliable and efficient and generally superior to those heretofore known.

Another object is to provide such a time delay which is adapted to delay the closing of the switch but which provides for a quick substantially unimpeded opening thereof.

A further object of the invention is the provision of such a device embodying a dash pot for the timing element.

Another object is to provide such a device embodying a dash pot which is located within the body of the switch, thus rendering the device compact and well protected from accidental inury.

A further object is to provide such a device which is readily adjustable to regulate the timing thereof and which accurately maintains such adjustment.

A further object of the invention is the provision of such a device which is economical to manufacture, is easily assembled and requires but few parts to be added to the switch assembly.

Other objects and advantages of the invention will become apparent from the following description taken in connection with the accompanying drawings in which:-

Fig. 1 is an elevation of an automatic switch parts being in axial section;

Fig. 2 is an enlarged expanded view in perspective oi certain of the parts;

Fig. 3 is an enlarged detail in section of certain parts of the switch shown in normal posiion;

Fig. 4 is a similar view showing the parts in operative position;

Fig. 5 is a similar view showing the parts in their position at the instant the switch has been opened; and

Fig. 6 is a schematic view of an automatic starting device embodying the improved automatic switch, incorporating the novel time delay element. I

Referring first to Fig. 1 of the drawings, the switch 9 comprises a casing III of any convenient form having a switch controlling solenoid I and a contact controlling solenoid l2 rigidly mounted therein. Solenoid H is adapted to control the position of a switch member l3 which when in its closed position bridges a pair of contacts l4 and IE to complete a starting motor circuit. One end of the coil I6 of solenoid H is connected to a binding post ll while the opposite end of said coil is connected to a bracket l8 mounted rigidly er 2| of solenoid I, electrically insulated there from, and is yieldably held against a shoulder 22 thereon as by means of a spring 23. Spring 23 15 is held in position and connected to plunger 2| by suitable means such as a dished Washer 23 riveted on the end of plunger 2| and forming a seat for the outer end of said spring. Plunger 2|, is formed in two parts 2| and 2| which fit 20 loosely within a cylindrical core 29 of solenoid Parts 2| and 2| are fixed together in any suitable way as by means of a threaded connection 24. Part 2| is provided as best shown in Fig. 2 with portions 25 and 26 of progressively reduced diameters forming shoulders 21 and 28 respectively and cooperating with the end of part 2| I to form annular chambers or spaces within the cylinder 29. Part 2 I is also provided with a longitudinal slot 30 extending throughout its length.

A cup valve of any suitable material is loosely mounted in the space between members 2 and 21 with its inturned portion 32 adapted to rest against shoulder 28 and its cylindrical portion adapted to surround the portion 25 of member 35 2|. Valve 3| has a working 'fit within cylinder 29, and may if desired be provided with an expander 3 therein to ensure an air-tight fit.

It will be noted that the space between the shoulder 2801 member 2 l and shoulder 33 formed by the end of 2| is considerably greater than the thickness of the inturned portion 32 of the cup valve 3| and of expander 3|, so that the cup valve is mounted on the plunger 2| with considerable longitudinal lost motion. When cup valve 3| rests against shoulder 33 it forms with such shoulder an obturator preventing the escape of air past the member 2|, but when the valve rests against the shoulder 28 air can readily pass through the space between shoulder 33 and inturned portion 32 and traverse the longitudinal slot 30.

The end oi cylinder 29 opposite that through which plunger 2| protrudes is closed by suitable means such as a plug 34 threaded within casing Ill and having a tight fit within said cylinder. Plug 34 may be provided with an adjustable bleeder which as illustrated comprises a channel 35 axially traversing the same, and a radial open ing 36 intersecting said channel. A plug 31 of suitable compressible material such as rubber or fibre is pressed against the opening of channel 35 as by means of threaded plug 38, the pressure being regulated by adjusting the plug to vary the rate of flow of air through said channel.

Plunger 2| is normally maintained in the position illustrated in Figs. 1 and 3 by means such as a spring 39 hearing against a partition member 40 of casing in at one end and against a collar 4! fixed on the plunger 2| at its other end. The length of the stroke of plunger 2i may be regulated by means such as the adjustable stop 42 mounted in casing Ill and forming an abutment for said plunger.

In Fig. 6 of the drawings one form of electrical connections is shown whereby the automatic switch may be used in an automatic starting device for internal combustion engines. A battery 50, engine driven generator G, automatic cut-out 5i and ammeter A are connected as shown or in any usual or preferred manner so that the generator will charge the battery while the engine is running. A starter of the automatic mesh type indicated generally at 52 is adapted to be energized by said battery, and switch 3 is designed to automatically control the actuation thereof whenever the ignition switch 53 is closed by the operator.

For this purpose, a cable 54 is arranged to connect the ungrounded end of battery 50 to contact M of switch 9. Contact i5 is connected through a single turn solenoid 55 to cable 55 leading to the starter 52. Switch controlling solenoid l I is connected to the ignition circuit by a lead 51 so that closure of the ignition switch 53 will energize said solenoid if contacts l9, l8 are closed. A voltage coil 58 forming a part of solenoid i2 is connected to the starter circuit at 59 and to the ground at 60, and a generator coil 5| is connected to the generator circuit at 52 and is also grounded at 60.

In operation, when the ignition switch 53 is closed, solenoid I I draws plunger 2i down, closing switch i3, i4, I 5 and causing the energization of the starter. Series coil 55 and voltage coil 58 are also simultaneously energized and exert opposing forces on contact plunger l9, coil 55 acting to hold the contact closed, and coil 53 tending to open the contact. As long as the starter is cranking the engine the current in the starter circuit is so heavy that coil 55 is stronger than coil 58, and contact I! is held closed. When the engine starts, however, the load on the starting motor is relieved and the starting current is reduced so that coil 53 overcomes coil 55 and withdraws contact plunger i9 from contact bracket l3, opening the circuit through switch solenoid H and releasing switch member i3. The battery connection to the starter is thus broken, but since voltage coil 58 is still connected to the motor, the contact l9 will be held open by the slight current generated by the spinning of the motor armature in its residual field. Before the starting motor has stopped, the generator coil H has become sufficiently energized by the generator G to retain the contact l9 open as long as the engine is running.

If the engine should stall for any reason, the generator coil 5i becomes deenergized, allowing contact I9 to close and the operation is repeated as long as the ignition switch remains closed.

The time delay device which forms the subject matter of the present invention is provided in order to allow the engine to come completely to rest before the switch l3, l4, I5 is allowed to close. This time delay is furnished by the dash pot action of the valve 3| in cylinder 23 since during the inward stroke of plunger 2| valve 3! rests against the shoulder 33 and forms there- 10 with a tight piston. The time delay may be regulated either by adjusting the plug 33 to vary the rate of escape of air through the channel 35 or by varying the stroke of plunger 2| by means of the adjustable stop l2. 16

Since large amounts of current are carried in the starting circuit, it is obvious that contacts I 3, l4, and I5 will be subject to heavy arcing if the break of said contacts is not instantaneous. With this purpose in view, the valve 3i is given 20 the lost motion referred to with respect to plunger 2|, so that return movement of plunger 2| is unimpeded by the friction of said valve in the cylinder 29.

This operation is best illustrated in Figs. 4 and 25 5 of the drawings. Fig. 4 illustrates the position of the parts when the switch is closed. It will be noted that valve 3! rests against shoulder 33 and spring 23 is slightly compressed in holding switch member i3 against contacts I and I5. 30 When the circuit through coil I 6 is broken by the control solenoid i2, (Fig. 1) spring 39 immediately expands and moves plunger 2i outwardly to the position shown in Fig. 5. As there illustrated, it will be seen that a clean break of the contacts is obtained by the time the lost motion between valve 3| and plunger 2! has been taken up.

Although but one embodiment of the invention has been illustrated and described in detail, it will be understood that this structure is not exclusive and further embodiments will now suggest themselves to those skilled in the art and certain parts may be combined, altered or omitted and changes made in the arrangement and mode of operation thereof without departing from the spirit of the invention.

Reference will therefore be had to the claims hereto appended for a definition of the scope of the invention.

What is claimed is:--

1. An automatic electric switch including a fixed pole piece, a movable armature cooperating therewith, a contact element, a yielding connection between the armature and contact'which is loaded when the switch is closed and permits the armature to engage the 'pole piece to close the magnetic circuit therethrough, means for retarding the switch closing motion of the armature, said retarding means having a lost motion connection with said armature to allow an unimpeded initial switch opening movement thereof to unload the yielding connection and break away said contact.

2. An automatic electric switch including a fixed pole piece, a movable armature cooperating therewith, a contact element, a yielding connection between the armature and contact which is loaded when the switch is closed and permits the 70 armature to engage the pole piece to close the magnetic circuit therethrough, means for retarding the switch closing motion of the armature, said retarding means having a lost motion connection with said armature to allow an unimpeded initial switch opening movement thereo! to unload the yielding connection and break away said contact, said armature having an abutment adapted to engage the contact element to break open the switch during the lost motion of the armature with respect to the retarding means.

3. A magnetic switch for automatic starting mechanism including fixed and movable contacts, operating means for the movable contact including a yielding connection for maintaining the engagement of the contacts, retarding means for said operating means, and means for rendering the retarding means inoperative tor a portion of the stroke of the operating means greater than that which loads the yielding connection.

4. A magnetic switch for automatic starting mechanism including fixed and movable contacts, operating means for the movable contact includ-- ing a magnetic plunger and a spring loaded by final closing movement of the plunger for hold-v ing the contacts closed, and retarding means for the plunger having a lost motion connection thereto which allows a suflicient'free movement 10 of the plunger to unload said spring and break, said contacts.

MAURICE P. WHITNEY

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