What is claimed is:
1. An oscillatory drive unit for use in an oscillating system to be oscillated substantially at the resonance point of the oscillating system, wherein the oscillating system includes a mass to be oscillated and a countermass, to which the mass is connected by resilient coupling means,
said oscillatory drive unit comprising:
a piston-cylinder-component for energization by a gas under pressure, the cylinder of the piston-cylinder-component being adapted to be operatively connected to either the mass or the countermass and the piston of the piston cylinder component having connecting means being adapted to be operatively connected to the respective other of the mass or countermass, wherein,
the piston-cylinder-component comprises a cylinder chamber being defined by an inner end wall and the inner side wall of the cylinder and a first end face of the piston, the opposite or second end face of the piston being provided with said connecting means,
the piston is arranged for reciprocal movement between a first end position in which the first end face of the piston is close to the inner end wall of the cylinder and a second end position in which the first end face of the piston is most remote from the inner end wall of the cylinder,
the piston-cylinder-component has inlet means for the gas under pressure, such inlet means being operative to introduce gas under pressure into the cylinder chamber within an energizing range of piston positions being defined by a first energizing position and a second energizing position of the piston, the first energizing position being closer to the cylinder end wall than the second energizing position,
the piston-cylinder-component has venting means for venting the cylinder chamber to the environment, which venting means are operative within a venting range of piston positions being defined by a first venting position and a second venting position of the piston, the first venting position being closer to the cylinder end wall than the second venting position,
the energizing range of piston positions being close to or including the first end position of the piston, and the venting range of piston positions being close to or including the second end position of the piston,
the actual reversal points of movement of the piston adjusting themselves under operating conditions of the oscillating system.
2. The drive unit according to claim 1, wherein the resilient coupling means between the mass and the countermass are spring means.
3. The drive unit according to claim 1, wherein
the inlet means for the gas under pressure comprise a gas supply duct provided in the cylinder wall and having an outlet port opening into the inner cylinder sidewall,
the venting means comprise a venting duct provided in the cylinder wall and having an intake port opening into the inner cylinder side wall,
the piston is provided with a piston channel, which piston channel opens with one end into the outer side wall of the piston and communicates with its other end with the cylinder chamber,
at least one communicating space is provided at the interface of the outer piston side wall and the inner cylinder side wall,
the inlet means for the gas under pressure being operative when during the movement of the piston, both, the outlet port of the gas supply duct and said one end of the piston channel are in communication with a communicating space, and
the venting means being operative when during movement of the piston both, the intake port of the venting duct and said one end of the piston channel are in communication with a communicating space.
4. The drive unit according to claim 3, wherein a first communicating space is provided, into which the outlet port of the gas supply duct opens, and a second communicating space, into which the intake port of the venting duct opens, the first and the second communicating spaces both being formed as circumferential grooves in the inner cylinder side wall.
5. The drive unit according to claim 4, wherein the second communicating space and the venting duct are unitary in that the circumferential groove forming the second communicating space is axially open to the cylinder end.
6. The drive unit according to claim 3, wherein only a single communicating space is provided at the outer side wall of the piston, said one end of the piston channel opening into said single communicating space.
7. The drive unit according to claim 6, wherein said single communicating space is formed by a circumferential groove in the outer side wall of the piston.
8. The drive unit according to claim 6, wherein said single communicating space is defined by axially spaced piston rings protruding from the outer side wall of the piston.
9. An oscillating system with a mass driven for oscillation substantially at the resonance point, the system incorporating at least one drive unit according to claim 1.
10. The system of claim 9 being an oscillating conveyor.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An electrical connector, comprising:
an insulative housing defining an aperture therethrough;
a plurality of contacts retained in the insulative housing;
a shell defining a through hole corresponding to one side of the aperture;
a board lock comprising a base with a bore defined through the base, the bore being corresponding to the other side of the aperture; and
a fastener extending through the through hole and through the aperture and the bore, the fastener comprising a resisting portion abutting against the shell and a rivet portion extending beyond the bore, the rivet portion being hollow to form a recess therein and defining a plurality of notches in communication with the recess to separate the rivet portion into several discontinuous parts, and wherein the discontinuous parts of the rivet portion are riveted to abut against the base of the board lock.
2. The electrical connector according to claim 1, wherein the fastener comprises a middle portion connecting the resisting portion and the rivet portion, the middle portion being received in the aperture.
3. The electrical connector according to claim 2, wherein the middle portion is contractive with respect to the resisting portion.
4. The electrical connector according to claim 2, wherein the rivet portion is contractive with respect to the middle portion.
5. The electrical connector according to claim 2, wherein the middle portion and the aperture comprise at least one matable surface, respectively, to prevent rotatability therebetween.
6. The electrical connector according to claim 1, wherein the plurality of notches extend along girth of the rivet portion.
7. The electrical connector according to claim 1, wherein the shell is stamped from metal sheet and partially enclosing a front surface of the insulative housing, the shell comprising a flat mating portion to be attached to the front surface of the insulative housing and a D-shaped projection protruding from the mating portion.
8. The electrical connector according to claim 1, wherein the fastener is nut and the resisting portion defines a plurality of inner screw threads recessed therein.
9. An electrical connector comprising:
an insulative housing defining one through aperture;
a plurality of contacts disposed in the housing;
a metallic shell covering one side of the housing and forming therein at least one through hole in alignment with the through aperture;
a board lock having a board locking leg and a housing attaching section located on the other side of the housing;
a fastener having a resisting portion seated upon the shell with internal threads therein, a middle portion extending from the resisting portion through the through hole and the through aperture, and rivet portion located behind the middle portion;
wherein
the rivet portion defines a plurality of notches to divide said rivet portion into several discontinuous parts circumferentially, and said discontinuous parts of the are riveted to abut against the housing attaching section.
10. The electrical connector according to claim 9, wherein the middle portion is contractive with respect to the resisting portion, and the rivet portion is contractive with respect to the middle portion.
11. The electrical connector according to claim 9, wherein the plurality of notches extend along girth of the rivet portion.
12. The electrical connector according to claim 9, wherein the rivet portion is riveted radially outwardly for abutment against the housing attaching section of the board lock.
13. The electrical connector according to claim 9, wherein the housing attaching section of the board lock defines a bore through which the rivet portion extends.
14. A riveted fastener, comprising:
a resisting portion;
a hollow rivet portion which defines a recess and a plurality of notches in communication with the recess to separate the rivet portion into several discontinuous parts; and
a middle portion integrally connecting the revisiting portion and the rivet portion.
15. The riveted fastener according to claim 14, wherein the middle portion is contractive with respect to the resisting portion, and the rivet portion is contractive with respect to the middle portion.
16. The riveted fastener according to claim 14, wherein the middle portion is polygonal.
17. The riveted fastener according to claim 14, wherein the plurality of notches extend along girth of the rivet portion.