Fluid handling – Systems – Supply and exhaust
Reexamination Certificate
2002-02-01
2004-02-03
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Systems
Supply and exhaust
C091S529000, C137S557000
Reexamination Certificate
active
06684905
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a construction machine with a piping structure of pilot pipe.
2. Description of the Related Art
Conventionally, one of pilot ports of direction control valves is determined according to operating direction of an operating valve, when pilot pressure derived from the operating valve by means of a control lever is applied to the pilot ports of direction control valves. As a result, working direction of various hydraulic actuators is determined correspondingly to the operating direction of the operating valve. If operating pattern is switched, a switching valve is provided between the operating valve and the direction control valves. By switching the switching valve, the operating pattern can be switched.
In
FIG. 5
, an example of pilot pipe structure having the switching valve is shown. Pilot pressure derived from left/right operating valve (hereinafter, referred to as remote control valve)
19
a
,
19
b
by means of operation of a control lever not shown is applied to one of the direction control valves
4
-
9
selected by switching pipe ports of the switching valve
17
′. The pilot pipes
20
a
,
20
b
extending from the switching valve
17
to the direction control valves
6
-
9
are provided with a pressure sensor block
17
c
′. Monitoring of pressure is carried out by means of output signal from the pressure sensors
21
a
,
21
b
provided in the block
17
c′.
In this case, because the pilot pipes
20
a
,
20
b
connecting the switching valve
17
′ and the direction control valves
6
-
9
to each other are provided with the pressure sensor block
17
c
′, the number of pipe connecting positions and pipe assembly parts such as joints and the like becomes larger. Accordingly, arrangement of pipe becomes complex. Specifically, when pipes are required to be arranged in a small space such as a small sized hydraulic excavator, arrangement of pipes becomes more complex because of condensation of the pipe assembly parts.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a construction machine with a piping structure of pilot pipe capable of decreasing the number of pipe connecting positions and pipe assembly parts such as joints to simplify arrangement of pipe.
The piping structure of pilot pipe in a construction machine according to the present invention has following construction.
The piping structure of pilot pipe comprises: a switching valve for applying pilot pressure derived from an operating valve to one of a plurality of pilot ports of direction control valves; a pressure sensor for detecting the pilot pressure; and detection ports provided in a body of the switching valve for guiding the pilot pressure to the pressure sensor.
In this case, because the body of the switching valve is provided with the detection ports for guiding the pilot pressure to the pressure sensor, the switching valve has functions of a pressure sensor block in common. As a result, the pressure sensor block need not be provided as in the conventional art. Accordingly, the number of pipe connecting positions and pipe assembly parts is decreased as many as the block. For this reason, improvement of quality and costreduction can be accomplished.
Also, because space for providing the pressure sensor block is not required, the space can be used usefully to simplify arrangement of pipe.
REFERENCES:
patent: 4970941 (1990-11-01), Reinhardt
patent: 4986165 (1991-01-01), Miyaoka
patent: 7-20342 (1995-04-01), None
Kobelco Construction Machinery Co., Ltd.
Michalsky Gerald A.
LandOfFree
Construction machine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Construction machine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Construction machine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3298988