Measuring and testing – Test stand – For engine
Reexamination Certificate
2002-10-24
2004-09-14
Lefkowitz, Edward (Department: 2855)
Measuring and testing
Test stand
For engine
Reexamination Certificate
active
06789412
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an oil pressure signal output device and more particularly to an oil pressure signal output device responsive to signals produced by manual operations inside a vehicle or by external operations including radio control or others from outside the vehicle to output oil pressure signals according to the operations to a hydraulic apparatus.
2. Discription of the Related Art
The driver's cab of working vehicles including a hydraulic excavator is equipped with an oil pressure signal output device for outputting a pilot pressure oil according to the operations of an operation lever or others. As for this oil pressure signal output device, an operator sways an operation lever back and forth, rightward and leftward, or obliquely to manipulate it manually, thereby manipulating pressure reducing valves through the respective pistons. Then, the pressure reducing valves output oil pressure signals of pilot pressure oil to hydraulic apparatuses according to a quantity of the operation. The actuation of the hydraulic apparatuses controls the operations of a vehicle or working machine.
Now,
FIG. 25
is a sectional view of a manual oil pressure signal output device having an operation lever. In the manual oil pressure signal output device
50
(hereinafter referred to as PPC valve
50
), the single operation lever
7
is swayed back and forth, or rightward and leftward, whereby four pressure reducing valves
14
corresponding to four pistons
4
,
6
respectively (the pistons
3
,
5
are not shown) output oil pressure signals according to the displacement of the pistons, more specifically pilot pressure oil, toward operating valves (not shown), which is a hydraulic apparatus, to switch the operating valves. Controlling the operating valves controls the operation of a hydraulic motor for driving a vehicle, a hydraulic cylinder for actuating a working machine, or the like.
An electric oil pressure signal output device for outputting pilot pressure oil in response to electric signals may be provided. This electric oil pressure signal output device is used in a case where an operator manipulates a remote operation device at a place away from a vehicle, such as the case of working at a disaster-stricken district, to activate a working vehicle. Based on the control commands sent from the remote operation device by radio, the controller outputs a control command current to the electric oil pressure signal output device and the electric oil pressure signal output device outputs pilot pressure oil with a pressure according to an amount of this command current.
FIG. 26
is a sectional view showing the electric oil pressure signal output device. Individual electric oil pressure signal output devices
60
are provided corresponding to the four pressure reducing valves
14
of the PPC valve
50
respectively. When the electric oil pressure signal output devices
60
are manipulated remotely, the operation of a hydraulic motor for driving use, a hydraulic cylinder for working machines, or the like can be controlled. Each electric oil pressure signal output device
60
has a electromagnetic, pressure-proportional pressure reducing valve
27
, which is actuated by a solenoid, and it is hereinafter referred to as EPC valve
60
. In the EPC valve
60
, the thrust proportional to an amount of command current flowing through the solenoid coil
25
acts on the plunger
26
in the direction of U to actuate the spool
28
, thereby outputting pilot pressure oil with a pressure according to the command current.
While
FIGS. 25 and 26
use the same reference numerals for constituent elements as those of the elements in the description of the embodiments of the invention, their description are omitted here.
As shown in
FIG. 27
, inside driver's cab of a vehicle, there are provided a PPC valve
50
and an EPC valve
60
separately, and further separately provided a shuttle valve
30
connected to the PPC valve
50
and EPC valve
60
. The shuttle valve
30
outputs pilot pressure oil from one of the PPC valve
50
and EPC valve
60
, which is under higher pressure than the other. This pilot pressure oil is input an operating valve for controlling pressure oil to be supplied to a hydraulic motor or a working machine. Therefore, when an operator manipulates an operation lever or a remote operation device, the operating valve is switched by the pilot pressure oil, thereby enabling a vehicle to run or a working machine to be actuated.
However, in the above conventional construction, when a PPC valve
50
, EPC valve
60
and shuttle valve
30
are provided as separate units inside driver's cab of a vehicle, it is required to connect the PPC valve
50
, EPC valve
60
and shuttle valve
30
through piping including a hose, and thus a large occupied area is needed. This causes the problem that the remaining space except these hydraulic apparatuses in a driver's cab becomes relatively small, which makes it difficult to place other vehicle-mounted apparatuses.
The invention was made in consideration of these actual conditions, so it is a first challenge of the invention to provide an oil pressure signal output device using a small occupied area, thereby reducing an occupied area of hydraulic apparatuses in a driver's cab to make a space except hydraulic apparatuses larger.
As a solution thereof, we have offered suggestions, Japanese patent application No. 2000-340612 and 2000-346711 (JP-A-2002-147407).
In the meantime, in recent years, it has become common practice for working vehicles including a hydraulic excavator to be mounted with various attachments including a clamshell bucket or a breaker in addition to a working machine, such as a regular excavator and thus the contents of works have spread. For this reason, an operating valve for controlling a hydraulic apparatus for an attachment use is additionally required, and it is necessary to provide a PPC valve
50
and EPC valve
60
for the purpose of switching this operating valve, and either the set of an electric switch and EPC valve
60
, or the set of an electric lever and EPC valve
60
inside the driver's cab to enable an operator to conduct manual operations inside the driver's cab and to perform the manipulations by a remote operation device outside the cab. Incident to this, however, the addition of the EPC valve
60
inside the driver's cab leads to the needs for connecting additional piping with this EPC valve
60
, whereby the occupied area of the hydraulic apparatus becomes larger. On this account, providing a new EPC valve
60
for the attachment use inside the driver's cab causes an additional problem that a space except the hydraulic apparatus relatively becomes smaller.
Further, there may be a case where an attachment is additionally mounted after shipment. Also, in this case, it is strongly desired to provide an oil pressure signal output device which can be easily mounted with an attachment and can be manipulated readily.
SUMMARY OF THE INVENTION
The invention was made focusing on the problem and relates to an oil pressure signal output device. Therefore, it is an object to provide an oil pressure signal output device, which permits easy integration of a new EPC valve for an attachment use and manipulation from inside and outside a driver's cab, and which is capable of making the occupied area of hydraulic apparatuses smaller and a space except the hydraulic apparatuses larger.
To attain the above objects, an oil pressure signal output device according to a first embodiment of the invention includes: a manual oil pressure signal output device for outputting an oil pressure signal based on a manual operation; at least one first electric oil pressure signal output device for outputting an oil pressure signal based on an electric signal; and selecting output means for selecting either an oil pressure signal output from said manual oil pressure signal output device or an oil pressure signal output from said first electric o
Hori Shuuji
Mototani Masayoshi
Davis Octavia
Komatsu Ltd.
Lefkowitz Edward
Varndell & Varndell PLLC
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