Valves and valve actuation – Electrically actuated valve – Including solenoid
Reexamination Certificate
2000-05-24
2002-05-21
Bomberg, Kenneth (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Including solenoid
C251S368000
Reexamination Certificate
active
06390443
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
The present invention relates to a composite magnetic member comprising at least one non-magnetized part and at least one ferromagnetized part, both parts being continuously and integrally formed, a process for producing the member and an electromagnetic valve using the member, and particularly to a composite magnetic member capable of fully maintaining ferromagnetic and non-magnetic characteristics against changes in temperature, a process for producing the member and an electromagnetic valve using the member.
2) Description of the Related Art
In generating a magnetic circuit in products such as electromagnetic valves, etc. by discretely providing a ferromagnetic part and a non-magnetic part in one product, it is necessary to make a mild steel part from a ferromagnetic material and an austenitic stainless steel part from a non-magnetic material individually, then assemble the ferromagnetic part and the non-magnetic part together while joining the parts properly by bonding, for example, by soldering, to make a member for the magnetic circuit. However, in making a member for the magnetic circuit in this manner, it is necessary to make a plurality of parts from a ferromagnetic material and a plurality of parts from a non-magnetic material individually and assemble such pluralities of the parts, while joining them by bonding. Thus, many steps and much labor are required for making such a member, complicating the procedure.
It is known that ordinary austenite stainless steel, high manganese steel, etc. are in a non-magnetic state after solid-solution treatment, but can be given a ferromagnetic property by cold working at room temperature to induce and generate a martensite structure. However, the degree of ferromagnetization obtained by this procedure is not high and thus it is actually difficult to apply this procedure to the production of members for the magnetic circuit.
It is also possible as a means for locally non-magnetizing part of a ferromagnetic material such as mild steel, etc. to diffuse an austenitizing element such as Mn, Cr, Ni, etc. into the ferromagnetic material from the surface, but such a means still has a problem in the production of members for the magnetic circuit.
JP-A-63-161146 discloses materials utilizable as a magnetic scale by optimizing the composition of austenite stainless steel or high manganese steel and working procedures for such materials to make members having both ferromagnetic and non-magnetic properties at the same time, where metastable austenite stainless steel is cold drawn into wires, thereby ferromagnetizing the austenite stainless steel based on martensitizing of austenite structure and part of the martensitized wires are further subjected to a local solid-solution treatment to locally non-magnetize the martensitized wires on the basis of local back-austenitization. Members having both ferromagnetic and non-magnetic properties at the same time can be obtained thereby. In this case, the composite magnetic members disclosed in JP-A-63-161146 can have a satisfactorily ferromagnetized part and a satisfactorily non-magnetized part, as integrated together, which can work satisfactorily under the ordinary circumstances, but no measures have been taken against temperatures at which the non-magnetized parts are to be used. That is, under severe temperature circumstance such as an extremely low temperature circumstance, a martensite structure is generated on the non-magnetized part, thereby transforming the non-magnetic properties to ferromagnetic properties. This has been a problem.
Currently available electromagnetic valves work as follows: a magnetic circuit is generated by passing an electric current through a coil in the valve, and a plunger is actuated through a sleeve undergoing magnetic working by the generated magnetic circuit. Particularly when an electromagnetic valve is used for oil-hydraulic control, the plunger must slide oil-tight along the inside surface of the sleeve. The conventional sleeve is made from a non-magnetic material, and to make the plunger behavior more sensitive, the magnetic circuit must be permeated through the non-magnetic material, and thus the force of excitation of the coil itself must be increased. Still furthermore, it is possible to ferromagnetize only part of the sleeve through which the magnetic circuit is to permeate. In the sleeve structure made by integrating a plurality of parts by bonding, the bonding must be carried out by soldering, welding, or the like to make the sleeve, and thus considerable post-working is required for obtaining desired dimension, shape and precision. Thus, there is a post-working problem.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a composite magnetic member comprising at least one satisfactorily ferromagnetized part and at least one satisfactorily non-magnetized part, both parts being continuously and integrally formed, which can work under severe circumstances such as an extremely low temperatures; a process for producing the member; and an electromagnetic member using the member.
At first, the present inventors have carefully checked what physical characteristics are desirable for a composite magnetic member having satisfactory ferromagnetic and non-magnetic characteristics at the same time under ordinary circumstances, and have found that a composite magnetic member is required to comprise a non-magnetized part having a relative magnetic permeability &mgr; of not more than 1.2 and the remaining ferromagnetized part having a magnetic flux density B
50
of not less than 0.3 T at the same time except at the transition region between the non-magnetized part and the ferromagnetized part and except parts particularly not required for the ferromagnetic characteristics.
To satisfy the above-mentioned requirements, the present inventors have selected the following composition which can generate a stable austenite structure at room temperature and also generate a martensite structure by cold working to make the cold worked parts ferromagnetic and can give satisfactory magnetic characteristics.
A metallic member that can meet the above-mentioned requirements has a composition which comprises not more than 0.6% C, 12 to 19% Cr, 6 to 12% Ni, not more than 2% Mn, not more than 2% Mo, not more than 1% Nb, and the balance being Fe and inevitable impurities, where it is desirable that:
Hirayama's equivalent H eq=[Ni %]+1.05 [Mn %]+0.65 [Cr %]+0.35 [Si %]+12.6 [C %] is 20 to 23%;
Nickel equivalent Ni eq=[Ni %]+30 [C %]+0.5 [Mn %] is 9 to 12%, and
Chromium equivalent Cr eq=[Cr %]+[Mo %]+1.5 [Si %]+0.5 [Nb %] is 16 to 19%, wherein % is and will be hereinafter by weight.
As to Hirayama's equivalent, reference is made to Nihon Kinzoku Gakkaishi (Journal of the Society of Metallurgy of Japan), 34 No. 5, 507-510 (1970); 34 No. 8, 826-829 (1970); 34 No. 8, 830-835 (1970); 35 No. 5, 447-451 (1971).
The C content is selected to be not more than 0.6% in the above-mentioned composition of the metallic member because shapability by working is lowered with increasing carbide content, though the magnetic characteristics can be satisfied over 0.6% C. The Cr content is selected to be 12 to 19% and the Ni content to be 6 to 12%, Since non-magnetic properties, for example, a relative magnetic permeability &mgr; of not more than 1.2, cannot be obtained below the lower limit Cr and Ni contents, whereas above the higher limit Cr and Ni contents, B
4000
, a magnetic flux density when the intensity of magnetic field is 3.980 A/m, cannot be made less than 0.3 T (0.3 tesla). When the Mn content is over 2%, the shapability by working is lowered. Thus, the upper limit Mn content is selected to be 2%.
Furthermore, specific amounts of Mo and Nb can be contained in the metallic member. Mo, when contained, can effectively lower a Ms point, an
Inui Tsutomu
Katayama Yoshitada
Majima Youzou
Sasaki Hakaru
Shibata Takayuki
Bomberg Kenneth
Harness Dickey & Pierce PLC
Keasel Eric
Nippondenso Co. Ltd.
LandOfFree
Composite magnetic member, process for producing the member... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Composite magnetic member, process for producing the member..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Composite magnetic member, process for producing the member... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2878740