GB1604480A - Solenoids - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO SOLENOIDS (71) We, LEDEX INC., a corporation organised under the laws of the State of Ohio, United States of America, of 123 Webster Street, Dayton, Ohio 45401, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to electrical solenoids and, more particularly, to improvements in or modifications of the invention disclosed in the complete specification of our prior patent application No. 1577051.

Our aforementioned patent specification describes and claims an electrical solenoid in which an armature is movable within an armature cavity defined by a coil assembly which comprises a base and pole made from magnetic material and inter-connected by a sleeve of non-magnetic material, said base and pole being telescopically engaged in opposite ends of the sleeve and being in axially spaced relation, and an electrical coil having its turns wound in tension about the sleeve so as to compress the latter into firm engagement with the portions of the base and pole telescoped within the sleeve. That specification is particularly concerned with wet plunger solenoids in which hydraulic fluid from valves operated by the solenoids is permitted to enter the plunger or armature cavities of the solenoids.It has now been discovered that the principles of the invention described in our prior specification are equally applicable to dry plunger or dry solenoid constructions, that is, solenoid constructions limited to use in situations when their armature cavities are not subjected to hydraulic fluid pressure. Hence, the present invention consists in an electrical solenoid as claimed in our prior specification which is a dry solenoid construction. It enables a highly efficient thermal and magnetic connection to be formed between the base, the pole and the sleeve, and the close proximity of the turns of the electric coil to these parts not only enhances the magnetic efficiency, but also enhances the thermal efficiency of the unit.

An axial air gap may be provided within the non-magnetic or non-ferrous sleeve, between the pole and the base. This sleeve may consist of a section of low cost tubing material cut accurately to length to define the spacing between the pole and the base.

In order that the invention may be more readily understood, reference will now be made to the accompanying drawings, in which: Fig. I is a longitudinal section of a dry solenoid embodying the invention; and Fig. 2 is a transverse section taken generally along the line 5-5 of Fig. 1.

In the dry solenoid illustrated in Figs. 1 and 2 of the accompanying drawings, parts corresponding to those of the wet solenoid illustrated in the drawings of our prior specification No. 1577051 are provided with like reference numerals plus 100. The wet solenoid construction is fully described in our prior specification and the dry solenoid will only be described herein insofar as is necessary for the understanding of the present invention.

Hence, the case 110 is formed of magnetic or ferrous material and has a front flange 111 at the open end of the case. The flange 111 may be as shown in Fig. 3 in connection with the flange 11, or alternatively, it may be provided with external threads for mounting the solenoid, as a cartridge-type solenoid.

The coil or spool assembly 112 is made up essentially of three separate pieces, namely, a base 114. a hub or pole 115, and a tubular spacer or sleeve 116. The base and pole are formed of magnetic or ferrous material and have generally the same configuration as that described in our prior specification. The nonmagnetic or non-ferrous sleeve 116, however, may be formed of a length of tubing matrial which has been accurately cut to a desired length. The sleeve thus defines the spacedapart distance of the base and pole and, accordingly, defines a working air gap 116b in the axial space between the base and the pole. Low cost aluminium or brass tubing or the like may be employed for this purpose, which forms a slip fit over the respective cylindrical sections 1 14a and 115a of the adjacent magnetic parts.The end cap 125 need not be sealed in a fluid tight manner, although conventional seals may be! em- ployed where dust, fluids, or other contaminations are anticipated. The end cap 125 may be a simple press fit into the open end of the case 110 and may be formed of either magnetic or non-magnetic material in accordance with the desired characteristics of the solenoid.

The armature 120 is somewhat modified from the armature 20 described in our prior specification in that axial passageways therethrough may also be eliminated. Additionally, it has been found advantageous to support the armature 120, at its inner end, on a sleeve bearing 128. The bearing 128 has an inner surface mounted on the armature 120 and has an outer surface forming a close running fit with the inside diameter of the cylindrical portion 1 14a of the base 114. The bearing 128 may be formed of sintered porous bearing metal, such as bronze, and in appropriate cases, impregnated with a desired lubricant.A second sleeve bearing 129, preferably formed of the same material as that of the bearing 128, is supported in the end cap portion 125a and slidably guides the shaft 122, so that the armature 120 is guided at one end by the bearing 128 and is guided at its remote end by the bearing 129 in association with the shaft.

As in the case of the solenoid described in our prior specification, the turns of the electric coil 150 are wound in direct engagement with the outer surface of the sleeve 116, and a layer 152 of insulating tape, shown in somewhat exaggerated thickness, in Fig. 1, is preferably applied before winding to provide electrical isolation for the coil 150. Also, the coil 150 is wound in tension into the annular space defined by the radial shoulders of the hub and base, and the interfitting outer cylindrical surface of the sleeve, causing the sleeve 116 to be compressed about the interfitted cylindrical sections therein. In this manner, an excellent thermal bond and mechanical connection is formed between the sleeve 116 on the one hand and the interfitted base and pole portions on the other hand.

In the present solenoid the movable plunger 35 of shown in our prior specification has been omitted. In its place, a nonmagnetic button 135 is inserted with a head 136 received within the armature cavity and positioned to come into abutment with the armature 120 in the retracted position of the armature, as shown in Fig. 1. The button 135 prevents the armature 120 from coming into direct contact with the base 114.

It is further understood that the shaft 122 may be extended through the armature 120, or a suitable connection made thereto through an aperture in the axial end 1 14b of the base 114 to provide an electrical feedback signal. One such electrical feedback signal arrangement is shown in our U.S. patent No.

3,870,931.

WHAT WE CLAIM IS: 1. An electrical solenoid as claimed in claim I of our patent specification No.

1577051 which is a dry solenoid construction (as hereinbefore defined).

2. A solenoid as claimed in claim 1 hereof, in which there is an axial air gap within the sleeve and between the pole and the base.

3. A solenoid as claimed in claim 1 or 2 hereof, including end wall means supporting the armature for axial movement in the armature cavity.

4. A solenoid as climed in claim 3 hereof, including a bearing sleeve disposed on said armature in sliding engagement with an inside cylindrical surface of the base.

5. A solenoid as claimed in claim 1, 2, 3 or 4 hereof in which the base has a shoulder projecting radially outwardly of the sleeve and forming one wall of a coil cavity, and the pole also has a shoulder projecting radially outwardly of the sleeve and forming an opposite wall of the coil cavity.

6. A solenoid as claimed in any one of the preceding claims hereof, in which the sleeve is formed from brass.

7. An electrical solenoid constructed and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. adjacent magnetic parts. The end cap 125 need not be sealed in a fluid tight manner, although conventional seals may be! em- ployed where dust, fluids, or other contaminations are anticipated. The end cap 125 may be a simple press fit into the open end of the case 110 and may be formed of either magnetic or non-magnetic material in accordance with the desired characteristics of the solenoid. The armature 120 is somewhat modified from the armature 20 described in our prior specification in that axial passageways therethrough may also be eliminated. Additionally, it has been found advantageous to support the armature 120, at its inner end, on a sleeve bearing 128. The bearing 128 has an inner surface mounted on the armature 120 and has an outer surface forming a close running fit with the inside diameter of the cylindrical portion 1 14a of the base 114. The bearing 128 may be formed of sintered porous bearing metal, such as bronze, and in appropriate cases, impregnated with a desired lubricant.A second sleeve bearing 129, preferably formed of the same material as that of the bearing 128, is supported in the end cap portion 125a and slidably guides the shaft 122, so that the armature 120 is guided at one end by the bearing 128 and is guided at its remote end by the bearing 129 in association with the shaft. As in the case of the solenoid described in our prior specification, the turns of the electric coil 150 are wound in direct engagement with the outer surface of the sleeve 116, and a layer 152 of insulating tape, shown in somewhat exaggerated thickness, in Fig. 1, is preferably applied before winding to provide electrical isolation for the coil 150. Also, the coil 150 is wound in tension into the annular space defined by the radial shoulders of the hub and base, and the interfitting outer cylindrical surface of the sleeve, causing the sleeve 116 to be compressed about the interfitted cylindrical sections therein. In this manner, an excellent thermal bond and mechanical connection is formed between the sleeve 116 on the one hand and the interfitted base and pole portions on the other hand. In the present solenoid the movable plunger 35 of shown in our prior specification has been omitted. In its place, a nonmagnetic button 135 is inserted with a head 136 received within the armature cavity and positioned to come into abutment with the armature 120 in the retracted position of the armature, as shown in Fig. 1. The button 135 prevents the armature 120 from coming into direct contact with the base 114. It is further understood that the shaft 122 may be extended through the armature 120, or a suitable connection made thereto through an aperture in the axial end 1 14b of the base 114 to provide an electrical feedback signal. One such electrical feedback signal arrangement is shown in our U.S. patent No. 3,870,931. WHAT WE CLAIM IS:

1. An electrical solenoid as claimed in claim I of our patent specification No.

1577051 which is a dry solenoid construction (as hereinbefore defined).

2. A solenoid as claimed in claim 1 hereof, in which there is an axial air gap within the sleeve and between the pole and the base.

3. A solenoid as claimed in claim 1 or 2 hereof, including end wall means supporting the armature for axial movement in the armature cavity.

4. A solenoid as climed in claim 3 hereof, including a bearing sleeve disposed on said armature in sliding engagement with an inside cylindrical surface of the base.

5. A solenoid as claimed in claim 1, 2, 3 or 4 hereof in which the base has a shoulder projecting radially outwardly of the sleeve and forming one wall of a coil cavity, and the pole also has a shoulder projecting radially outwardly of the sleeve and forming an opposite wall of the coil cavity.

6. A solenoid as claimed in any one of the preceding claims hereof, in which the sleeve is formed from brass.

7. An electrical solenoid constructed and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.