Patent Application
20110033289
1. Field of the Invention
This invention relates to a vacuum cleaner, more particularly to a bypass-type motor protecting device for a vacuum cleaner.
2. Description of the Related Art
A conventional vacuum cleaner generally includes a bypass-type motor protecting device mounted upstream of a motor intake port such that, once a hose is clogged, the protecting device can be opened to permit flow of cool ambient air into a body housing of the cleaner over a suction motor.
Referring to
The strength of the biasing force of the biasing member 5 must be precise, and must be measured in order to provide a good motor protecting effect without compromising the suction effect of the vacuum cleaner. However, no adjusting means is provided in the conventional bypass-type motor protecting device for adjusting the biasing force of the biasing member in a convenient and precise manner.
The object of the present invention is to provide a bypass-type motor protecting device for a vacuum cleaner which can simplify the adjusting operation of the strength of the biasing force of a biasing member to permit convenient and precise level adjustment.
According to this invention, the bypass-type motor protecting device includes a casing, a seat body, a valve body unit, and a biasing member. The casing has a tubular wall which includes a mounting end that defines an access bore, and that is adapted to be fitted into a bypass opening of a body housing of a vacuum cleaner, and which surrounds an axis and extends along the axis and inwardly to define a passageway therein. The casing further has an inner abutment wall which extends radially to confront the passageway, and which has an internal port that is adapted to communicate the passageway with an airflow duct in the body housing. The seat body extends radially to close the access bore, and has an inner peripheral wall which defines a bypass entry port that is in fluid communication with the passageway. Aback pressure is generated in the bypass entry port as a result of clogging of the airflow duct by trapped dust. The valve body unit is disposed to be movable in the passageway between a closed position, where entry of air into the passageway through the bypass entry port is denied, and an open position, where, by virtue of the back pressure generated in the airflow duct, air is permitted to enter into the passageway through the bypass entry port. The valve body unit includes a valve disc, a plunger body, and an abutment member. The valve disc is configured to be engaged with and disengaged from the seat body when the valve body unit is in the closed and open positions, respectively. The plunger body has an operated head which is disposed to be externally accessible through the bypass entry port, and which is mounted on the valve disc to be revolvable about the axis, and a threaded shank which extends from the operated head along the axis into the passageway. The abutment member is spaced apart from the inner abutment wall along the axis by an axial distance, and which is threadedly engaged with the threaded shank such that rotation of the operated head about the axis results in the change of the axial distance. The biasing member abuts against the inner abutment wall and the abutment member to provide a biasing force to bias the valve disc to the closed position. The biasing force is varied in strength by the change of the axial distance.
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment of the invention, with reference to the accompanying drawings, in which:
Referring to
The casing 10 has a tubular wall 12 which includes a mounting end 121 defining an access bore 120, and which surrounds an axis (L) and extends along the axis (L) and inwardly to define a passageway 11 that is communicated with the access bore 120. The casing 10 further has a plurality of retaining protrusions 123 and a plurality of abutment portions 127 extending radially from the mounting end 121, and an inner abutment wall 124 which extends radially to confront the passageway 11, and which has an internal port 126 that is adapted to communicate the passageway 11 with the airflow duct. The tubular wall 12 further has a plurality of through holes 125 disposed adjacent to the inner abutment wall 124 and angularly displaced from one another about the axis (L) for facilitating fluid communication between the passageway 11 and the airflow duct.
The end cap 20 includes a seat body 21 extending radially to close the access bore 120, and having an inner peripheral wall 23 which defines a bypass entry port 22 that is in fluid communication with the passageway 11. A back pressure is generated at the bypass entry port 22 as a result of clogging of the airflow duct by trapped dust, thereby creating a reduced pressure upstream of the suction motor. The end cap 20 further includes a flange member 24 which has an angularly extending insert 241 that extends along the axis (L), and that is configured to be inserted together with the mounting end 121 into the bypass opening 102 so as to enable the mounting end 121 to be fitted into the bypass opening 102, and a flange portion 242 that extends radially and outwardly from the angularly extending insert 241, and that is spaced apart from the seat body 21 axially and radially so as to form a surrounding gap 243. Thus, during assembly of the protecting device onto the body housing 100 of the vacuum cleaner, the casing 10 is inserted into the body housing 100 through the bypass opening 102 to permit the abutment portions 127 to abut against an inner wall of the body housing 100, and the end cap 20 is mounted on the casing 10 to permit the retaining protrusions 123 to extend outwardly through the surrounding gap 243 and rest on the flange portion 242. Subsequently, the insert 241 is fitted into the bypass opening 102 together with the mounting end 121, thereby securing the seat body 21 to the body housing 100.
The valve body unit 30 is disposed to be movable in the passageway 11 between a closed position, as shown in
Preferably, the valve body unit 30 includes a plurality of guided members 33 which are disposed on the confining wall 32 and each of which extends axially to terminate at a stop end 331. Each of the through holes 125 in the tubular wall 12 of the casing 10 is configured to extend axially and towards the mounting end 121, and terminates at a barrier end 128 which guards against further movement of the stop end 331 in the closed position so as to minimize impact of the valve disc 31 on the seat body 21 when the valve body unit 30 is brought to the closed position. Moreover, the guided members 33 are slidably and respectively mounted in the through holes 125 to guide the movement of the valve body unit 30 along the axis (L).
The biasing member 40 has two ends respectively abutting against the inner abutment wall 124 and the abutment member 35 to provide a biasing force to bias the valve disc 31 to the closed position.
As shown in
With the bypass-type motor protecting device of the present invention, the operation of adjusting the strength of the biasing force of the biasing member 40 can be simplified to permit a convenient and precise level adjustment. Specifically, by rotating the operated head 341 with a tool bit to change the axial distance between the abutment member 35 and the inner abutment wall 124, the strength of the biasing force of the biasing member 40 can be varied. The adjusting operation can be conducted conveniently and precisely after the manufacture and assembly operations are completed without the need to remove any component parts from the vacuum cleaner and change the biasing member.
While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretations and equivalent arrangements.
