subject: Types Of Proportional Solenoid Valves [print this page] In a proportional solenoid valve, a solenoid main body includes a coil, a valve seat member having a seat portion, a valve element that is displaced in accordance with a current applied to the coil so as to be brought into and out of contact with the seat portion, and a valve guide portion that is arranged coaxially with the seat portion and guides the displacement of the valve element.
The housing is attached to the solenoid main body so that a space is formed between the housing and the valve seat member. A seal member made of an elastic material is provided in the space between the housing and the valve seat member.
In a conventional proportional solenoid valve, a valve element is displaced while being guided by a valve guide portion that is provided for a solenoid main body. Also, a valve seat member having a seat portion, which the valve element is brought into and out of contact with, is fixed to a housing coupled to the solenoid main body (see JP 2002-525524 A, for instance).
As described above, in the conventional proportional solenoid valve, the valve element is provided on the solenoid main body side and the seat portion is provided on the housing side, so that an error occurs in the coupling position of the housing with reference to the solenoid main body due to machining tolerances of the coupling portion between the solenoid main body and the housing. As a result, coaxiality between the valve element and the seat portion is lowered. Also, when the housing is welded to the solenoid main body, a distortion occurs in the housing, which causes a positional shift of the valve element with reference to the seat portion. The influence of the distortion varies depending on welding conditions such as the amount of welding heat and a welding range, so that it is difficult to manage the positional shift. Further, when the housing is made of a resin, the positional shift of the valve element with reference to the seat portion occurs also due to deformation of the housing resulting from operating temperature.
The present invention has been made in order to solve the above-mentioned problems, and provides a proportional solenoid valve which is capable of improving accuracy of positional shift of a valve element with reference to a seat portion.
A proportional solenoid valve according to the present invention includes a solenoid main body, a housing, and a seal member. The solenoid main body includes a coil, a valve seat member having a seat portion, a valve element that is displaced in accordance with a current applied to the coil so as to be brought into and out of contact with the seat portion, and a valve guide portion that is arranged coaxially with the seat portion and guides the displacement of the valve element.
The housing is attached to the solenoid main body so that a space is formed between the housing and the valve seat member. The seal member is made of an elastic material and is provided in the space between the housing and the valve seat member. The valve seat member is attached to the valve guide portion, thereby making it possible to improve positional accuracy of the valve element with reference to the seat portion.
Note that, in the first to third embodiments, there was described a proportional solenoid valve of a normally high type whose output pressure is high at the time of non-energization and is decreased in accordance with an increase in applied current. However, the present invention is also applicable to a proportional solenoid valve of a normally low type whose output pressure is low at the time of non-energization and is increased in accordance with an increase in applied current. Also, the housing can be shared between two types of proportional solenoid valves.
