Tool driving or impacting – Passage in manipulating handle for drive motor motive fluid – Motive fluid control valve in handle passage
Patent
1996-06-10
1998-08-25
Smith, Scott A.
Tool driving or impacting
Passage in manipulating handle for drive motor motive fluid
Motive fluid control valve in handle passage
B23B 4504, F16K 1114
Patent
active
057974624
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a pneumatic power tool of the type having a housing with a pistol type handle, a motor in the housing, a pressure air inlet passage and an exhaust air passage extending substantially in parallel to each other through the handle, and a manually operable throttle valve located in the air inlet passage.
In this type of power tool, as for example the tool disclosed in GB 2 098 528, there is incorporated a throttle valve of the type having a longitudinally displaceable valve stem with a push button for manual operation at its outer end and a valve head at its inner end. The inner end portion of the valve stem extends through an air inlet opening, and a seat surrounding the air inlet opening is arranged to be sealingly engaged by the valve head on the valve stem.
This common type of throttle valve is disadvantageous for two reasons, namely that it requires a relatively high activation force to be opened and does not make possible a smooth start and slow running of the tool.
A previous throttle valve design providing a smooth two-step start and slow running of the tool is described in U.S. Pat. No. 4,258,799. This known throttle valve, however, is disadvantageous in that it is bulky and does not enable integration of a forward/reverse valve function.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a pneumatic power tool including a throttle valve which has a smooth two-step opening function and a very compact design, and which suitably incorporates a reverse valve function.
Another object of the invention is to provide a power tool throttle valve with smooth starting and slow running properties and which in a compact design suitably integrates a forward/reverse function.
A preferred embodiment of the invention is described below with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a side view, partly in section, of a power tool according to the invention.
FIG. 2. shows, on a larger scale, a fraction of the power tool in FIG. 1.
FIG. 3 shows a cross section along line III--III in FIG. 2.
FIG. 4 shows a longitudinal section through a throttle valve according to the invention.
FIG. 5 shows a cross section along line V--V in FIG. 4.
DETAILED DESCRIPTION
The power tool shown on the drawings comprises a housing 10 with a pistol type handle 11 and a throttle valve assembly 12. Within the housing there is located a pneumatic motor (not shown) which is supplied with motive pressure air through an inlet passage 13 and which exhausts air though an exhaust passage 14. The inlet and exhaust passages 13, 14 extend substantially in parallel to each other through the handle 11.
The throttle valve assembly 12, which is manually operable by a push button 16, forms a part of the inlet passage 13. The throttle valve assembly 12 also traverses the exhaust passage 14 and comprises an outer sleeve 17 with two lateral openings 18, 19 which for part of the exhaust passage 14. The throttle valve assembly 12 will be described further detail below.
The handle 11 comprises a central tubular stem 20 which forms a part of the inlet passage 13 and which is formed by a protrusion 21 from the housing 10 and two tube sections 22, 23 interconnected by a thread joint 24 and secured to the housing protrusion 21 by means of another thread connection 25. The outer tube section 23 is formed with a threaded socket 27 for connection of a pressure air supply conduit.
The inner end of the outer tube section 23 forms an annular shoulder 28 which engages an oppositely facing shoulder 29 on a hallow grip element 30 to firmly secure the latter to the tool housing 10. The grip element 30, which is supported on a neck portion 31 on the housing 10, surrounds the tubular stem 20 and defines together with the latter a part of the exhaust passage 14. The shoulder 29 is formed by an inner ring portion 32 of the grip element 30 and is supported on one side by a stay member 33.
A tubular outlet diffusor 34 is supported coaxially around the outer tu
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patent: 4258799 (1981-03-01), Eckman
patent: 4476942 (1984-10-01), Elkin
patent: 5228523 (1993-07-01), Rahm
patent: 5303781 (1994-04-01), Lin
patent: 5377769 (1995-01-01), Hasuo et al.
Atlas Copco Tools AB
Smith Scott A.
LandOfFree
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