Oil pressure signal output device

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 oil pressure signal output device to output the selected oil pressure signal outside, wherein the manual oil pressure signal output device for controlling a first hydraulic apparatus, the first electric oil pressure signal output device and the selecting output means are integrated, a second electric oil pressure signal output device for controlling a second hydraulic apparatus different from the first hydraulic apparatus is removably provided and abutting against the first electric oil pressure signal output device.

According to the first embodiment, in the oil pressure signal output device, the manual oil pressure signal output device for controlling a first hydraulic apparatus (PPC valve), the first electric oil pressure signal output device (EPC valve) and selecting output means (hereinafter referred to as shuttle valves) are integrated; a second EPC valve for controlling a second hydraulic apparatus different from the first hydraulic apparatus abuts against the first EPC valve and is removably provided. For this reason, the second EPC valve for the other hydraulic apparatus can be mounted easily and compactly even when an additional (second) hydraulic apparatus for a new attachment is required at the time of or after the shipment. Further, even when an additional second EPC valve is provided, it is not required to connect it through piping including a hose, so that the occupied area of hydraulic apparatuses in a driver's cab can be reduced. Therefore, it is possible to secure a larger space other than that of hydraulic apparatuses in a driver's cab.

An oil pressure signal output device according to a second embodiment of the invention includes: a manual oil pressure signal output device for outputting an oil pressure signal based on a manual operation by an operator in a driver's cab; a first electric oil pressure signal output device for outputting an oil pressure signal based on an electric signal from outside the driver's cab; and selecting output means for selecting either an oil pressure signal output from the manual oil pressure signal output device or an oil pressure signal output from the first electric oil pressure signal output device to output the selected oil pressure signal outside, wherein the manual oil pressure signal output device for controlling a first hydraulic apparatus, the first electric oil pressure signal output device and the selecting output means are integrated, a pump passage for supplying pressure oil from a hydraulic pump, and a tank passage for draining return oil into a tank, which are respectively brought into communication with a side surface of the first electric oil pressure signal output device, a second electric oil pressure signal output device for controlling a second hydraulic apparatus different from the first hydraulic apparatus can be mounted additionally, and covers for blocking the pump passage and the tank passage are removably provided on side surfaces of the first electric oil pressure signal output device.

In the oil pressure signal output device according to the second embodiment, the PPC valve, the first EPC valve and the shuttle valves are integrated; the EPC valve for a second hydraulic apparatus can be additionally mounted on a side surface of the first EPC valve; and covers are removably provided, so that it is possible to obtain the same actions and advantages as those of the first embodiment and also to manipulate the second EPC valve using an electric lever, switch or the like from outside a driver's cab. This also enables an additional working machine such as an attachment to be manipulated from outside a driver's cab and enables the remote manipulation. Further, a new attachment can be mounted easily even after shipment, thereby improving the maintainability.

In a third and fourth embodiments, in addition to the conditions of the first and second embodiments, a bottom surface of the manual oil pressure signal output device and an upper surface of the first electric oil pressure signal output device abut against each other to be integrated, and the second electric oil pressure signal output device is removably provided on a side surface of the first electric oil pressure signal output device.

According to the third and fourth embodiments, a bottom surface of the PPC valve and an upper surface of the first EPC valve abut against each other to be integrated, and the second EPC valve is removably provided on a side surface of the first EPC valve, so that it is possible to install a given number of the second EPC valves on both side surfaces of the first EPC valve easily. Additionally, because the second EPC valve is mounted on the side surface of the first EPC valve, it is not subjected to the interference of the piping for the first EPC valve, so that the second EPC valve can be easily mounted and removed and therefore the maintainability can be improved.

In a fifth to eighth embodiments, in addition to the conditions of the first to fourth embodiments, the manual oil pressure signal output device, the first electric oil pressure signal output device, and the second electric oil pressure signal output device, which are mutually adjacent, are connected through pump passages and tank passages provided inside the respective oil pressure signal output devices and are connected to a common hydraulic pump and a common tank.

According to the fifth to eighth embodiments, the PPC valve, the first EPC valve, and the second EPC, which are mutually adjacent, are connected through pump passages and tank passages provided in their inside and are connected to a common hydraulic pump and a common tank. Therefore, it is not required to add neither pump line nor tank line when providing an EPC valve for manipulating a new attachment and it is possible to easily mount an oil pressure signal output device capable of manipulating a new attachment at the time of and after the shipment. Further, even when a new second EPC valve is provided, the connection through piping including a hose is not required, so that the occupied area of the hydraulic apparatuses in a driver's cab can be reduced. In addition, the need for adding a pump line and a tank line is eliminated, and it become possible to reduce the number of assembly steps and to improve the maintainability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a side sectional view of an oil pressure signal output device of the first embodiment;

FIG. 2

is a top plan outline view of

FIG. 1

;

FIG. 3

is a side view taken from a direction indicated by the arrow Z of

FIG. 2

;

FIG. 4

is a side view taken from a direction indicated by the arrow Y of

FIG. 2

;

FIG. 5

is a hydraulic circuit diagram of the first embodiment;

FIG. 6

is a sectional view taken along the line B—B of

FIG. 4

;

FIG. 7

is a sectional view taken along the line C—C of

FIG. 4

;

FIG. 8

is a sectional view taken along the line D—D of

FIG. 4

;

FIG. 9

is a schematic illustration of a pressure reducing valve for a PPC valve;

FIG. 10

is a schematic illustration of a pressure reducing valve for an EPC valve;

FIG. 11

is a sectional view taken along the line E—E of

FIG. 4

;

FIG. 12

is a sectional view taken along the line F—F of

FIG. 4

;

FIG. 13

is a plan sectional view of an EPC valve of an oil pressure signal output device of the second embodiment;

FIG. 14

is a partial front outline view of the EPC valve of

FIG. 13

;

FIG. 15

is a sectional view taken along the line C

1

—C

1

of

FIG. 14

;

FIG. 16

is a sectional view taken along the line E

1

—E

1

of

FIG. 14

;

FIG. 17

is a sectional view taken along the line F

1

—F

1

of

FIG. 14

;

FIG. 18

is a hydraulic circuit diagram of the second embodiment;

FIG. 19

is a hydraulic circuit diagram of another embodiment;

FIG. 20

is a plan sectional view of an EPC valve of the third embodiment;

FIG. 21

is a partial front outline view of an EPC valve of the third embodiment;

FIG. 22

is a sectional view taken along the line C

2

—C

2

of

FIG. 21

;

FIGS. 23A and 23B

are block diagrams of a selecting output means;

FIGS. 24A and 24B

are illustrations of a two-axis PPC valve used in the invention;

FIG. 25

is a sectional view of a conventional PPC valve;

FIG. 26

is a sectional view of a conventional EPC valve; and

FIG. 27

is a hydraulic circuit diagram showing the relationships among the PPC valve, EPC valve, and the shuttle valve.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments of an oil pressure signal output device according to the invention are hereinafter described in reference to the drawings Incidentally, the same constituent elements as the elements in the drawings used in the related art description are described below with the same reference numerals.

First, referring to

FIGS. 1

to

5

, an oil pressure signal output device

1

of a first embodiment is described.

FIG. 1

is a side sectional view of the oil pressure signal output device

1

(a sectional view taken along the line A—A of FIG.

2

);

FIG. 2

is a top plan outline view of

FIG. 1

;

FIG. 3

is a partial side outline view of

FIG. 1

(a side view taken from a direction indicated by the arrow Z of FIG.

2

);

FIG. 4

is a partial front outline view of

FIG. 1

(a side view taken from a direction indicated by the arrow Y of FIG.

2

); and

FIG. 5

is a hydraulic circuit diagram of the oil pressure signal output device

1

of the first embodiment. Additionally,

FIGS. 24A and 24B

are drawings for showing the move of an operation lever

7

in a PPC valve with 2-axis operation directions. The embodiment is described with reference to the move of this operation lever

7

.

As shown in

FIGS. 1

,

3

and

5

, an oil pressure signal output device

1

according to the invention mainly includes: a PPC valve

50

; at least one EPC valve

60

(e.g. four EPC valves here); and at least one shuttle valve

30

(e.g. four shuttle valves here). The upper surface of each of the EPC valves

60

abuts against the bottom surface of the PPC valve

50

. Both the valves

50

,

60

are coupled through bolts to be integrated. Between the PPC valve

50

and EPC valve

60

, which have been integrated, is interposed a shuttle valve

30

provided in an EPC valve body

61

having the EPC valve

60

mounted thereon.

In

FIGS. 1

,

2

and

3

, the bottom surface of the body

51

of the PPC valve

50

abuts against the upper surface of the EPC valve body

61

and they are coupled by bolts for valve body use

64

(See FIG.

3

), while on the opposite side surfaces of the EPC valve body

61

are installed EPC valves

60

(

60

F,

60

B,

60

R,

60

L in this drawing) corresponding to respective PPC-valve pressure reducing valves

14

(

14

F,

14

B,

14

R,

14

L in this drawing) of the PPC valve

50

.

On the side surfaces of the EPC valve body

61

other than the faces with which the EPC valves

60

installed, covers

63

are removably mounted by cover bolts

65

(See

FIG. 2

) to be integrated therewith. In association with this practice, the EPC valve body

61

is formed so that between the side surface of the EPC valve body

61

and each of the covers

63

can be added a given number of other EPC valves

60

A for actuating other hydraulic apparatuses as many as they are required, as described later. In the description below, the covers

63

on both the side surfaces are referred to as right-side cover

63

b

and left-side cover

63

a

, if required.

As shown in

FIGS. 3 and 5

, the body

51

of the PPC valve

50

is provided with a pump port Pu for connecting to a hydraulic pump

100

and a tank port Ta for connecting to a tank

110

. The pump port Pu communicates with an inside-PPC-valve pump passage

101

formed in the body

51

of the PPC valve

50

and with an inside-EPC-valve pump passage

103

formed in the EPC valve body

61

through the inside-PPC-valve pump passage

101

. The inside-PPC-valve pump passage

101

branches out into the inside-PPC-valve pump passage

101

and a passage

101

a

connecting to the inside-EPC-valve pump passage

103

inside the body

51

. Therefore, the PPC valve

50

and the EPC valves

60

are connected to a common hydraulic pump

100

in parallel.

The tank port Ta communicates with an inside-PPC-valve tank passage

111

formed in the body

51

of the PPC valve

50

and an inside-EPC-valve tank passage

113

formed in the EPC valve body

61

through this inside-PPC-valve tank passage

111

. The inside-PPC-valve tank passage

111

branches out into the inside-PPC-valve tank passage

111

and a passage

111

a

connecting to the inside-EPC-valve tank passage

113

inside the body

51

.

Therefore, the return oils from the PPC valve

50

and from the EPC valve

60

are returned to a common tank

110

, respectively, through the inside-PPC-valve tank passage

111

and the tank port Ta and through the inside-EPC-valve tank passage

113

, inside-PPC-valve tank passage

111

and tank port Ta.

Referring now to

FIGS. 6 and 7

.

FIG. 6

is a sectional view taken along the line B—B of FIG.

4

.

FIG. 7

is a sectional view taken along the line C—C of FIG.

4

and represents the structure inside the EPC valve

60

for brevity. As shown in

FIGS. 6 and 7

, the inside-EPC-valve pump passage

103

and inside-EPC-valve tank passage

113

, which connect each of the EPC valves

60

to the hydraulic pump

100

and tank

110

respectively, are blocked at both the end surfaces of the EPC valve body

61

by the covers

63

(the left-side cover

63

a

and right-side cover

63

b

in the drawings).

Therefore, a length of pump line

105

and a length of tank line

115

shown in

FIG. 5

can suffice for the lines for connecting between the hydraulic pump

100

and the pump port Pu and between the tank port Ta and the tank

110

respectively, so that it is possible to decrease the number of parts and the number of process steps for connecting the lines and to reduce the occupied area.

Referring to

FIGS. 1 and 5

again, wherein the EPC valve body

61

houses the shuttle valves

30

interposed between the PPC valve

50

and the respective EPC valves

60

. The shuttle valve

30

is an example of selecting output means that selectively outputs one of two types of oil pressure signals. The shuttle valve compares the pilot pressure oil of the PPC valve

50

with that of the EPC valve

60

in pressure to output the higher one as a pilot pressure. In other words, the shuttle valve

30

outputs the pilot pressure oil of the PPC valve

50

when the PPC valve

50

is manipulated and it outputs the pilot pressure oil of the EPC valve

60

when the EPC valve

60

is controlled.

The pressure of pilot pressure oil output from each of the shuttle valve

30

is output from the pilot discharge opening

20

provided in proper alignment with the EPC valve

60

on the side surface of the EPC valve body

61

through a pilot line

19

to each operating valve that is not shown. Incidentally, this pilot discharge opening

20

may be provided on the bottom surface St of the EPC valve body

61

.

Now, the PPC valve

50

is described in detail.

Referring to

FIGS. 1

,

2

,

5

,

24

A, and

24

B, wherein the PPC valve

50

mainly includes: a body

51

; an operation lever

7

provided swayably in two directions, namely back and forth FB, and rightward and leftward LR, with respect to the body

51

; a disc plate

9

provided on a lower portion of the operation lever

7

; four pistons

3

-

6

each provided movably up and down under the disc plate

9

in the body

51

on the back, forth, right or left sides of the operation lever

7

, the pistons

3

-

6

each capable of moving up and down through the disc plate

9

by swaying the operation lever

7

; and PPC-valve pressure reducing valves

14

for outputting pilot pressure oil in response to a quantity of swaying of the operation lever

7

through up-and-down movements of the pistons

3

-

6

.

For example, in a case where the PPC valve

50

, EPC valve

60

and pressure reducing valve

14

and others are distinguished as needs come up, the description will be done below while indicating these elements with the foregoing reference numerals followed by the letters of F, B, L and R, which correspond to the symbols used in

FIGS. 24A and 24B

for indicating the operation directions of the operation lever

7

, namely forward F, backward B, leftward L and rightward R. For instance, the PPC valve

50

for forward manipulation is indicated by the reference numeral of

50

F, and the PPC-valve pressure reducing valve

14

for forward manipulation is indicated by

14

F.

The operation lever

7

is mounted to the body

51

through the free joint

8

and disc plate

9

so that it can be freely swayed leftward/rightward, F, B on the sheet of FIG.

1

and in two directions orthogonal to this sheet, L, R. The disc plate

9

is mounted to the operation lever

7

so that it abuts against the tops (upper ends) of the pistons

3

,

4

,

5

and

6

at the bottom surface thereof.

As shown in

FIG. 1

, the four pistons

3

,

4

,

5

and

6

are provided so that the tops (upper ends) of the pistons protrude upward from the mounting plate

10

for mounting the oil pressure signal output device

1

. The pistons

3

,

4

,

5

and

6

are provided respectively at locations corresponding to the four operation directions of the operation lever

7

, as shown in FIG.

2

. For example, when the operation lever

7

is swayed in the F direction, the disc plate

9

pushes the piston

6

down by a stroke corresponding to the swaying quantity and therefore pilot pressure oil with a pressure corresponding to the stroke of the piston

6

is output from the PPC-valve pressure reducing valve

14

F. Additionally, when the operation lever

7

is swayed in the B direction, the disc plate

9

pushes the piston

4

down and thus pilot pressure oil with a pressure corresponding to the stroke of the piston

4

is output from the PPC-valve pressure reducing valve

14

B.

Similarly, swaying the operation lever

7

in the R or L direction causes the disc plate

9

to push the piston

3

or piston

5

, respectively, down corresponding to the swaying quantity, so that pilot pressure oil having a pressure corresponding to the stroke of the piston

3

or

5

is output from the PPC-valve pressure reducing valve

14

R or

14

L, respectively.

FIG. 8

shows a plan sectional view of the EPC valve and also it is a sectional view taken along the line D—D of FIG.

4

. As shown in

FIGS. 1 and 8

, the pilot pressure oil output from each of the PPC-valve pressure reducing valves

14

is supplied to the PPC-valve pilot pressure oil input portion

30

a

of the shuttle valve

30

from a PPC-valve pressure oil output chamber

15

f

formed below the PPC-valve pressure reducing valve

14

through a pilot passage

30

f

formed in the upper portion of the EPC valve body

61

.

The piston

6

is described as a representative below and the descriptions about the other pistons

3

,

4

and

5

are omitted because they have the same contents.

As shown in

FIG. 1

, between the piston

6

and the spring seat

51

a

of the body

51

is provided with a first spring

12

. Swaying the operation lever

7

in the F direction causes the piston

6

to be pushed down in a direction indicated by the arrow D against the urging force of the first spring

12

. An operator can obtain given operating feelings due to the urging force of this first spring

12

when swaying the operation lever

7

.

Referring to

FIG. 5

again, wherein the body

51

is provided with the PPC-valve pressure reducing valves

14

for each producing pilot pressure oil having a pressure corresponding to a piston thrust for each of the pistons

3

,

4

,

5

and

6

. The PPC-valve pressure reducing valves

14

of the pistons

3

,

4

,

5

and

6

are each connected in parallel to the inside-PPC-valve pump passage

101

provided in the body

51

through the respective pressure oil input portions

14

b

to be described later.

The body

51

is also provided with the inside-PPC-valve tank passage

111

. This PPC-valve tank passage

111

is individually connected in parallel to oil discharge portions

14

c

of the respective PPC-valve pressure reducing valves

14

, which will be described later, and it brings return oils back to the tank

110

. Also, the inside-PPC-valve tank passage

111

is connected with the inside-EPC-valve tank passages

113

through branch passages

111

a

and the return oil of the EPC valve

60

is brought back to the tank

110

through the body

51

.

Referring now to

FIG. 9

, which shows the PPC-valve pressure reducing valve

14

schematically.

In

FIG. 9

, the PPC-valve pressure reducing valve

14

has a spool sliding bore

14

a

formed inside the body

51

. In the spool sliding bore

14

a

is inserted a spool

15

pivotally, closely and slidably in a direction indicated by the arrow U or D. In the spool sliding bore

14

a

are also formed pressure oil input portions

14

b

for receiving pressure oil discharged from the hydraulic pump

100

.

One end of the spool

15

is connected through a second spring

13

with the piston

6

, and the spool

15

is arranged to receive a thrust according to an amount of the displacement of the piston

6

to slide within the spool sliding bore

14

a

. The body

51

, which shrouds a sliding surface on one end of the spool

15

, is also provided with an oil discharge portion

14

c

. The spool

15

has notch

15

a

formed in the sliding surface of one end thereof, while it has a pressure oil output portion

15

b

formed in the other end surface of the other end thereof.

Inside the spool

15

, there is formed an inner line

15

c

communicating between the notch

15

a

and the pressure oil output portion

15

b

. The pressure oil output portion

15

b

communicates from the PPC-valve pressure oil output chamber

15

f

through the PPC-valve pressure oil input portion

30

a

of the shuttle valve

30

to the pilot line

19

. Further, in the spool

15

, there are formed pressure receiving portions

15

d

,

15

e

for receiving a pressure of output pilot pressure oil.

Next, the EPC valve

60

is described in detail.

Referring to

FIGS. 1 and 6

again, in which the EPC valve

60

is provided with a solenoid coil

25

, a plunger

26

which receives a thrust produced in response to a current conducted in the solenoid coil

25

to be displaced, and an EPC-valve pressure reducing valve

27

for producing pilot pressure oil having a pressure corresponding to a thrust of the plunger

26

.

The plunger

26

is placed in a center axis portion of the cylindrical solenoid coil

25

. Additionally, one end of the plunger

26

is connected to one end of the spool

28

of the EPC-valve pressure reducing valve

27

.

This EPC-valve pressure reducing valve

27

is provided corresponding to each of the PPC-valve pressure reducing valves

14

. That is, a given number of the EPC-valve pressure reducing valves

27

, e.g. four EPC-valve pressure reducing valves here, are installed to the side surface of the EPC valve body

61

. As shown in

FIG. 6

, the EPC valve body

61

has an inside-EPC-valve pump passage

103

formed therein. The inside-EPC-valve pump passage

103

is connected to pressure oil input portions

27

b

of the EPC-valve pressure reducing valve

27

(which are described later in detail) in parallel. As described, the inside-EPC-valve pump passage

103

is connected to the inside-PPC-valve pump passage

101

formed in the body

51

of the PPC valve

50

and receives pressure oil of the hydraulic pump

100

through the body

51

. Also, the inside-EPC-valve pump passage

103

communicates with a plurality of connecting ports

104

provided in left-side and right-side end surfaces of the EPC valve body

61

and the connecting ports

104

are shut off with the left and right covers

63

a

,

63

b.

As shown in

FIG. 7

, inside-EPC-valve tank passages

113

,

113

a

are formed in the EPC valve body

61

. The inside-EPC-valve tank passages

113

,

113

a

are connected to oil discharge portions

27

e

of the EPC-valve pressure reducing valves

27

(See

FIGS. 1 and 10

) in parallel. As described above, the inside-EPC-valve tank passages

113

,

113

a

are connected to the inside-PPC-valve tank passage

111

formed in the body

51

of the PPC valve

50

to bring return oil back to the tank

110

through the body

51

. The inside-EPC-valve tank passages

113

a

each have one end portion connected to the oil discharge portion

27

e

and the other end portion connected to the inside-EPC-valve tank passage

113

. The inside-EPC-valve tank passage

113

communicates with connecting ports

114

provided in left-side and right-side end surfaces of the EPC valve body

61

, and the connecting ports

114

are shut off by the right and left covers

63

a

,

63

b.

Referring to

FIG. 10

, which shows the EPC-valve pressure reducing valve

27

schematically.

In

FIG. 10

, the EPC-valve pressure reducing valve

27

has a spool sliding bore

27

a

formed in the EPC valve body

61

. In the spool sliding bore

27

a

is inserted a spool

28

pivotally, closely and slidably in a direction indicated by the arrow U or D. In the spool sliding bore

27

a

are formed a pressure oil input portion

27

b

for inputting pressure oil discharged from the hydraulic pump

100

, and a gap

27

c

communicated with the pressure oil input portion

27

b

according to the displacement of the spool

28

. The gap

27

c

communicates with the pilot line

19

through the pressure oil output portion

27

d

, the EPC-valve pressure oil input portion

3

ob

of the shuttle valve

30

and a shuttle-valve pressure oil output portion

30

c.

The spool

28

has one end portion connected with the plunger

26

. On the opposite side, the EPC valve body

61

shrouding the other end portion of the spool

28

is provided with an oil discharge portion

27

e

. The oil discharge portion

27

e

is connected to the inside-PPC-valve tank passage

111

of the PPC valve

50

through the inside-EPC-valve tank passages

113

,

113

a.

The spool

28

slides inside the spool sliding bore

27

a

with the displacement of the plunger

26

. The spool

28

has a notch

28

a

formed in the sliding surface. Also, the spool

28

has an annular portion

28

b

in the sliding surface, which is located in the gap

27

c

and receives pilot pressure oil output from the gap

27

c

when the pressure oil input portion

27

b

and gap

27

c

communicate with each other through the notch

28

a.

In a case where a displacement of the spool

28

in a direction indicated by the arrow U is less than a given amount, or where a current flowing through the solenoid coil

25

is less than a given amount, the pressure oil input portion

27

b

does not communicate with the gap

27

c

and the pressure oil input portion

27

b

leads back to the tank

110

through a relief valve (not shown). In this case, the gap

27

c

communicates with the tank

110

through the oil discharge portion

27

e

, inside-EPC-valve tank passages

113

,

113

a

, PPC-valve tank passage

111

and tank port Ta. Therefore, a pressure of pressure oil output from the pressure oil output portion

27

d

is not increased.

In a case where a displacement of the spool

28

in a direction indicated by the arrow U exceeds a given amount, or where a current flowing through the solenoid coil

25

exceeds a given amount, the pressure oil input portion

27

b

communicates with the gap

27

c

through the notch

28

a

. As described above, pilot pressure oil enters the gap

27

c

and then it is output to the EPC-valve pressure oil input portion

30

b

of the shuttle valve

30

.

Next, the shuttle valve

30

is described in detail. Referring now to

FIGS. 11 and 12

, which show a sectional view taken along the line E—E of

FIG. 4 and a

sectional view taken along the line F—F of

FIG. 4

respectively. It should be noted that

FIGS. 11 and 12

represent a structure inside the EPC valve

60

for brevity.

FIG. 11

is a sectional view of the shuttle valve

30

, in which the shuttle valve

30

is provided in the EPC valve body

61

. This shuttle valve

30

includes: a PPC-valve pressure oil input portion

30

a

connected to the PPC-valve pressure reducing valve

14

; an EPC-valve pressure oil input portion

30

b

connected to the EPC-valve pressure reducing valve

27

; and the shuttle-valve pressure oil output portion

30

c

for outputting a pressure of the piiot pressure oil from the shuttle valve

30

to the pilot line

19

.

The PPC-valve pressure oil input portion

30

a

communicates with the PPC-valve pressure oil output chamber

15

f

of PPC-valve pressure reducing valve

14

through the PPC-valve pilot line

30

f

, as shown in

FIGS. 5 and 8

. Further, the EPC-valve pressure oil input portion

30

b

is connected to the pressure oil output portion

27

d

of the EPC-valve pressure reducing valve

27

through the EPC-valve pilot line

30

g

, as shown in

FIGS. 1

,

5

and

11

.

The shuttle valve

30

has a ball

31

inserted between the PPC-valve pressure oil input portion

30

a

and the EPC-valve pressure oil input portion

30

b

. The ball

31

is provided so as to close the PPC-valve pressure oil input portion

30

a

and the EPC-valve pressure oil input portion

30

b

freely. In a case where the ball

31

closes the EPC-valve pressure oil input portion

30

b

, the PPC-valve pressure oil input portion

30

a

communicates with the shuttle-valve pressure oil output portion

30

c

. In contrast, in a case where the ball

31

closes the PPC-valve pressure oil input portion

30

a

, the EPC-valve pressure oil input portion

30

b

communicates with shuttle-valve pressure oil output portion

30

c.

The shuttle-valve pressure oil output portion

30

c

communicates with the pilot line

19

through a shuttle-valve pilot passage

30

h

, as shown in FIG.

12

.

The oil pressure signal output device

1

can be manipulated by the manipulation section

35

shown in

FIG. 5

in addition to the operation lever

7

. The manipulation section

35

shown in

FIG. 5

is a wireless installation provided outside a driver's cab of a vehicle, which can send a control command by radio according to the manipulation of the manipulation section

35

. With this control command, an amount of a current to be flowed in the solenoid coil

25

is instructed. The receiving section

36

receives a control command sent by the manipulation section

35

. The control section

37

controls a current flowing through the solenoid coil

25

based on a control command received in the receiving section

36

.

Next, the actuation of the oil pressure signal output device

1

is described. First, a case where an operator manipulates the oil pressure signal output device

1

using the operation lever

7

inside the driver's cab is described with reference to

FIGS. 1-6

,

9

,

11

and

12

.

FIGS. 1

,

2

and

5

show a condition where the operation lever

7

stays in a neutral position. From this condition, swaying the operation lever

7

in the F direction causes the piston

6

to be pushed down through the disc plate

9

in a direction indicated by the arrow D. Then, the piston

6

displaces the spool

15

of the PPC-valve pressure reducing valve

14

F through the second spring

13

in a direction indicated by the arrow D. In a case where a displacement of the spool

15

in a direction indicated by the arrow D is less than a given amount, or where a quantity of swaying of the operation lever

7

is less than a given amount, the notch

15

a

of the spool

15

does not communicate with the pressure oil input portion

14

b

, and the notch

15

a

communicates with the tank

110

through the oil discharge portion

14

c

, PPC-valve tank passage

111

and tank port Ta. Therefore, a pilot pressure of the PPC-valve pressure oil output chamber

15

f

is not increased.

On the other hand, in a case where a displacement of the spool

15

in a direction indicated by the arrow D exceeds a given amount, or where a quantity of swaying of the operation lever

7

exceeds a given amount, the pressure oil input portion

14

b

of the PPC-valve pressure reducing valve

14

, which leads to the hydraulic pump

100

, opens into the notch

15

a

of the spool

15

, and pressure oil from the hydraulic pump

100

flows into the inner line

15

c

of the spool

15

depending on an overlapping area of the opening of the pressure oil input portion

14

b

and the notch

15

a

. Furthermore, the spool

15

receives a pressure of the pressure oil at the pressure receiving portion

15

d

,

15

e

to be displaced in a direction indicated by the arrow U shown in this drawing.

In association with this practice, an area of the opening portion where the pressure oil input portion

14

b

and the notch

15

a

overlap with each other is limited depending on a pressure of pilot oil. Thus, the pressure oil input to the PPC-valve pressure reducing valve

14

F from the hydraulic pump

100

undergoes a reduction in pressure and then it is output to the pilot line

19

through the shuttle valve

30

.

When swaying manipulation of the operation lever

7

becomes larger and thus the spool

15

is further pushed down, an opening area where the pressure oil input portion

14

b

and the notch

15

a

overlap with each other becomes larger and a pressure reduction amount of the pressure oil from the hydraulic pump

100

becomes smaller, and then a higher pressure of pilot pressure oil is supplied to the inner line

15

c

. The pilot pressure oil with a higher pressure that has entered the inner line

15

c

acts on the pressure receiving portions

15

d

,

15

e

of the spool

15

to cause the spool

15

to be displaced in a direction indicated by the arrow U shown in the drawing.

In this way, the spool

15

stops at a location where a pressure of pressure receiving portion

15

d

,

15

e

of the spool

15

and an urging force of the second spring

13

balance with each other, and a pressure of pilot pressure oil according to a quantity of swaying of the operation lever

7

is output to the PPC-valve pressure oil input portion

30

a

of the shuttle valve

30

through the PPC-valve pressure oil output chamber

15

f

and the pilot passage

30

f

inside the EPC valve.

As shown in

FIG. 11

, the pressure oil flowing into the PPC-valve pressure oil input portion

30

a

of the shuttle valve

30

moves the ball

31

leftward in the drawing (toward the left-side cover

63

a

) to close the EPC-valve pressure oil input portion

30

b

. This causes the PPC-valve pressure oil output chamber

15

f

of the PPC-valve pressure reducing valve

14

F corresponding to the piston

6

to communicate with the pilot line

19

through the shuttle valve

30

, shuttle-valve pressure oil output portion

30

c

and shuttle-valve pilot passage

30

h

, as shown in

FIGS. 1 and 12

.

Further, at this time, the pressure oil output portion

27

d

of the EPC-valve pressure reducing valve

27

F is cut off because the EPC-valve pressure oil input portion

30

b

of the shuttle valve

30

is closed. As for the PPC-valve pressure reducing valves

14

B,

14

L and

14

R except this one, while the pressure oil of the hydraulic pump

100

flows into them through the body

51

, the pressure oil input portion

14

b

is cut off by the spool

15

, thereby generating no pilot pressure oil.

In this manner, pilot pressure oil with a pressure depending on a quantity of swaying in the F direction of the operation lever

7

is output to the pilot line

19

. Likewise, in a case where the operation lever

7

is manipulated in the other directions, B, L and R to cause the pistons

3

,

4

and

5

to be displaced respectively, pilot pressure oils with pressures depending to quantities of swaying of the operation lever

7

in the respective directions are output to the pilot lines

16

,

17

and

18

shown in

FIGS. 5

,

24

A, and

24

B.

Next, referring to

FIGS. 1-6

and

FIGS. 10-12

, a case where construction machines including a hydraulic excavator are manipulated from outside a driver's cab is described.

FIGS. 1

,

2

and

5

show a case where no operator manipulates the machine and no current flows in the solenoid coil

25

. It is assumed that an operator manipulates the manipulation section

35

from outside the driver's cab to send a control command by radio in this condition. The control command is received in the receiving section

36

and sent to the control section

37

.

The control section

37

causes a current depending on an electrical quantity of the control command to flow in the solenoid coil

25

of the corresponding EPC valve

60

. As a result of this, the solenoid coil

25

produces a thrust depending on a quantity of the current to displace the plunger

26

inwardly in the drawing (in the U direction in

FIG. 10

, which hereinafter refers to a direction toward the center of the EPC valve body

61

), or toward the spool

28

. The spool

28

hereby receives a thrust caused by the plunger

26

to be displaced inwardly

When the spool

28

is displaced inwardly, the pressure oil input portion

27

b

, which leads to the hydraulic pump

100

, communicates with the notch

28

a

of the spool

28

, whereby pressure oil of the hydraulic pump

100

is supplied to the gap

27

c

through the notch

28

a

. The pilot pressure oil in the gap

27

c

acts on the annular portion

28

b

of the spool

28

to displace the spool

28

outwards in the drawing (in the D direction in

FIG. 10

, which hereinafter refers to a direction toward the plunger

26

).

In association with this practice, an area of the opening portion where the pressure oil input portion

27

b

and the notch

28

a

of the spool

28

overlap with each other is limited depending on a pressure of pilot oil. Thus, the pressure oil input to the EPC-valve pressure reducing valve

27

F from the hydraulic pump

100

undergoes a reduction in pressure and then it is output as pilot pressure oil through the gap

27

c

and the pressure oil output portion

27

d

and further output to the pilot line

19

through the shuttle valve

30

. In this time, the spool

28

stops at a location where a thrust of the plunger

26

and a pressure of the pilot pressure oil for pressing the annular portion

28

b

of the spool

28

balance with each other.

Controlling a current flowing through the solenoid coil

25

to become larger: displaces the spool

28

more inwardly; makes larger an opening area where the pressure oil input portion

27

b

and the notch

28

a

of the spool

28

overlap with each other; makes a decreasing pressure of pressure oil from the hydraulic pump

100

smaller; and supplies the gap

27

c

with pilot pressure oil having a higher pressure. The high-pressure pilot pressure oil which has entered into the gap

27

c

acts on the annular portion

28

b

of the spool

28

to displace the spool

28

outwardly. The spool

28

stops at a location where a pressure of the pilot pressure oil and a thrust of the plunger

26

balance with each other.

Thus, pilot pressure oil having a pressure according to an amount of the current flowing through the solenoid coil

25

can be produced. The resulting pilot pressure oil is output to the EPC-valve pressure oil input portion

30

b

of the shuttle valve

30

through the pressure oil output portion

27

d

of the EPC valve

60

F and the EPC-valve pilot line

30

g.

As shown in

FIG. 11

, the pressure oil which has flowed into the EPC-valve pressure oil input portion

30

b

of the shuttle valve

30

moves the ball

31

rightward in the drawing (toward the center of the EPC valve body

61

) to close the PPC-valve pressure oil input portion

30

a

. This causes the pressure oil output portion

27

d

of the EPC-valve pressure reducing valve

27

F corresponding to the piston

6

to communicate with the pilot line

19

from the shuttle valve

30

through the shuttle-valve pressure oil output portion

30

c

and the shuttle-valve pilot passage

30

h

, as shown in

FIGS. 1 and 12

.

During this time, the pressure oil output portion

15

d

of the PPC-valve pressure reducing valve

14

F is cut off because the PPC-valve pressure oil input portion

30

a

of the shuttle valve

30

is closed. While the pressure oil of the hydraulic pump

100

flows into the inside-EPC-valve pump passage

103

in the EPC valve body

61

through the body

51

, the EPC-valve pressure reducing valve

27

B,

27

L and

27

R except the valve

27

F produce no pilot pressure oil because their pressure oil input portions

27

b

are cut off with the respective spools

28

. The inside-EPC-valve tank passage

113

in the EPC valve body

61

serves to bring return oil back to the tank

110

through the inside-PPC-valve tank passage

103

of the body

51

because the EPC valve body

61

is cut off by the covers

63

a

,

63

b.

Thus, pilot pressure oil having a pressure according to a control command sent from the manipulation section

35

by radio is output to the pilot line

19

. This allows the manipulation of working vehicles from outside a driver s cab, which enables operators to manipulate such working machines from a remote location, even when a worksite is located in a dangerous place, such as a disaster-stricken district.

The first embodiment can provide the following advantages.

Hydraulic apparatuses including a PPC valve

50

, EPC valves

60

and shuttle valves

30

are integrated. This makes it possible to reduce the occupied area of the hydraulic apparatuses, thereby to secure a larger space available for setting apparatuses or devices other than hydraulic apparatuses. More specifically, the EPC valve body

61

is disposed, in which the shuttle valves

30

are incorporated on the bottom surface of the PPC valve

50

, and the EPC valves

60

are mounted on the opposed side surfaces thereof; the covers

63

for blocking the pump passage

103

and the tank passage

113

are attached removably on the other opposed side surfaces of the EPC valve body

61

. For this reason, in the case of attaching an additional attachment, it is enough only to provide an EPC valve

60

A for manipulating the additional attachment between the factory-supplied EPC valve body

61

and the covers

63

. This allows an oil pressure signal output device capable of manipulating an additional attachment to be easily mounted without the need for adding a pump line and a tank line even after shipment.

When providing the EPC valves

60

on side surfaces of the EPC valve body

61

and a pilot line

19

for outputting pilot pressure oil on the side surface or the bottom surface St below the EPC valves

60

, the EPC valves

60

are not subjected to the interference of the pilot line

19

, so that the EPC valves can be easily mounted and removed and therefore the maintainability can be improved.

Referring now to

FIGS. 13-18

, the first oil pressure signal output device

1

A of the second embodiment is described.

FIG. 13

is a plan sectional view of EPC valves of a first oil pressure signal output device

1

A relating to this embodiment (a sectional view taken along the line B

1

—B

1

of FIG.

14

), which is equivalent to FIG.

6

.

FIG. 14

is a partial front outline view, which is equivalent to the side view taken from the direction indicated by the arrow Y of FIG.

2

.

FIG. 15

is a sectional view of the EPC valves (a sectional view taken along the line C

1

—C

1

of FIG.

14

), which is equivalent to FIG.

7

.

FIG. 16

is a sectional view of the EPC valves (a sectional view taken along the line E

1

—E

1

of FIG.

14

), which is equivalent to FIG.

11

.

FIG. 17

is a sectional view of the EPC valves (a sectional view taken along the line F

1

—F

1

of FIG.

14

), which is equivalent to FIG.

12

.

FIG. 18

is a hydraulic circuit diagram of the first oil pressure signal output device

1

A. Now, it should be noted that FIGS.

15

—

17

represent the structure of the EPC valves

60

for brevity.

The first oil pressure signal output device

1

A illustrated in

FIGS. 13

,

14

and

18

is a result of adding another EPC valve

60

A for additionally manipulating another hydraulic apparatus to the oil pressure signal output device

1

of the first embodiment. More specifically, the first oil pressure signal output device

1

A has another first EPC valve

60

A attached to the right side surface of the EPC valve body

61

of the oil pressure signal output device

1

with the right-side cover

63

b

removed for a time and the right-side cover

63

b

is installed on the right side surface of this first EPC valve

60

A.

The first EPC valve

60

A includes a first EPC valve body

61

a

, and a pair of the EPC valves

60

a

,

60

b

mounted on the first EPC valve body

61

a

. The pair of EPC valves

60

a

,

60

b

are respectively installed in EPC-valve holes

66

formed on the opposed side surfaces of the first EPC valve body

61

a

, namely on the sides where the four EPC valves

60

F,

60

B,

60

R and

60

L in the EPC valve body

61

of the oil pressure signal output device

1

are mounted.

The pump passage

67

, which leads to the inside-EPC-valve pump passage

103

of the EPC valve body

61

, penetrates the first EPC valve body

61

a

and opens into the EPC-valve hole

66

. The pump passage

67

is connected with the pressure oil input portion

27

b

of each of the EPC valves

60

to supply the EPC valves

60

a

,

60

b

with pressure oil of the hydraulic pump

100

.

Referring to

FIG. 15

, in which a tank passage

68

, which is connected to the inside-EPC-valve tank passage

113

of the EPC valve body

61

, penetrates the first EPC valve body

61

a

to be formed therein. The tank passage

68

has one end portion shut off by the right-side cover

63

b

, a center portion connected with the inside-EPC-valve tank passages

113

a

, which are connected to the oil discharge portions

27

e

of the EPC valves

60

a

,

60

b

, and the other end connected to the inside-EPC-valve tank passage

113

of the adjacent EPC valve

60

. The oil discharge portions

27

e

of the EPC valves

60

a

,

60

b

are connected through the inside-EPC-valve tank passage

113

a

,

68

and

113

, and the inside-PPC-valve tank passage

111

to the tank

110

to bring return oils of the EPC valves

60

a

,

60

b

back to the tank

110

.

The pump passage

67

and tank passage

68

, which penetrate the first EPC valve body

61

a

, communicate with the inside-EPC-valve pump passage

103

and the inside-EPC-valve tank passage

113

in the adjacent EPC valve

60

respectively, and are covered by the right-side cover

63

b

at their right-side end surface of the first EPC valve body

61

a

to prevent pressure oil or return oil from leaking outside.

Referring to

FIGS. 16 and 17

, in which the first EPC valve body

61

a

is provided with pilot passages

69

for directing pilot pressure oils output from the EPC valves

60

a

,

60

b

to the respective pilot discharge openings

20

. These pilot passages

69

each have one end portion connected to the pressure oil output portion

27

d

of the EPC-valve pressure reducing valve

27

through the EPC-valve pilot line

30

g

, and the other end connected to the pilot discharge opening

20

.

To the pilot discharge openings

20

, the pilot lines

19

a

are each installed. The pilot lines

19

a

supply the respective pilot pressure oils output from the EPC valves

60

a

,

60

b

to an operating valve for an attachment (not shown).

In

FIG. 18

, the first oil pressure signal output device

1

A is provided with a manipulation section

70

for additionally manipulating another EPC valve

60

A in addition to the operation lever

7

and the manipulation section

35

, which are used for manipulating the oil pressure signal output device

1

shown in the first embodiment. The manipulation section

70

includes an electric operation lever

71

for manipulating the EPC valve

60

A from inside a driver's cab and a first manipulation section

35

a

for manipulating the EPC valve

60

A from outside the driver's cab.

As for the operation lever

7

and the manipulation section

35

, which are for manipulating the oil pressure signal output device

1

from inside and outside the driver's cab respectively, their descriptions are omitted because they are the same as those of the first embodiment. The first manipulation section

35

a

of the wireless installation is provided with an operating switch (not shown). When manipulating this operating switch, the first manipulation section

35

a

sends a control command by radio according to a quantity of the operation, like the manipulation section

35

. The receiving section

36

receives the control command sent by the first manipulation section

35

a

and send it to the first control section

37

a

. The first control section

37

a

controls a command current in the solenoid coil

25

of the corresponding EPC valve

60

based on the control command received in the receiving section

36

.

Inside the driver's cab, there are provided with the operation lever

7

and the electric operation lever

71

for the manipulating the EPC valve

60

A. In the electric operation lever

71

, a stroke sensor

72

for detecting the operation direction thereof and a quantity of the operation is attached. The stroke sensor

72

sends signals for the detected operation direction and the detected amount of stroke to the first control section

37

a.

The first control section

37

a

monitors a control command of the EPC valve

60

A based on signals of the operation direction of the electric operation lever

71

and an amount of stroke thereof, and a control command of the operating switch of the first manipulation section

35

a

to output a command current according to the higher control command to solenoid coils

25

of the EPC valves

60

a

,

60

b

. Based on this command current, each of the solenoid coils

25

controls the EPC valves

60

a

,

60

b

, as in the case of the EPC valves

60

of the first embodiment, and it outputs pilot pressure oil having a pressure in response to the command current to the pilot line

19

.

The pilot line

19

supplies the operating valve for an attachment (not shown), which is the additional hydraulic apparatus, with pilot pressure oils output from the EPC valves

60

a

,

60

b

differently.

Next, the actuation of the first oil pressure signal output device

1

A is described.

The description about a case where an operator manipulates the operation lever

7

inside the driver's cab or manipulates the device through the manipulation section

35

outside the driver's cab is omitted, because they are the same as in the case of the oil pressure signal output device

1

of the first embodiment. The respective cases where an operator manipulates the electric operation lever

71

inside the driver's cab and he or she manipulates the first manipulation section

35

a

outside the driver's cab are described here. For example, the electric operation lever

71

or first manipulation section

35

a

is manipulated to actuate the EPC valve

60

a

or

60

b

, and to supply pilot pressure oil to the operating valve for an attachment (not shown), which is an additional hydraulic apparatus, thereby manipulating the additional attachment, such as a clamshell.

In

FIG. 18

, when an operator manipulates the electric operation lever

71

inside a driver's cab, the stroke sensor

72

detects the operation direction and a quantity of the operation to send this detected signals to the first control section

37

a

. The first control section

37

a

outputs command currents according to the operation direction and an amount of stroke to the solenoid coil

25

of the corresponding EPC valve

60

a

or

60

b

to control the EPC valves

60

a

,

60

b

through the solenoid coils

25

by the same action as in the case of the EPC valves

60

of the first embodiment and to output pilot pressure oil having a pressure according to the command current to the pilot line

19

. This pilot pressure oil controls the operating valve for the attachment according to the operation direction and an amount of stroke of the electric operation lever

71

to actuate the attachment at a rate according to the amount of stroke.

Now, a case of manipulating the first manipulation section

35

a

outside a driver's cab is described. When manipulating the operating switch of the first manipulation section

35

a

, control commands are sent by radio according to the operation direction and a quantity of the operation and sent to the first control section

37

a

through the receiving section

36

.

The first control section

37

a

outputs a command current according to the size of the control command to the solenoid coil

25

of the corresponding EPC valve

60

a

or

60

b

, causes the solenoid coil

25

to produce a thrust according to an amount of the command current, controls the EPC valves

60

a

,

60

b

in the same manner as in the case of the electric operation lever

71

inside a driver's cab, and actuates the attachment according to the operation direction at a rate according to a quantity of the operation of the operating switch.

In the second embodiment, an example in which the electric operation lever

71

is used for the manipulation inside a driver's cab as a manipulation section

70

of an additional EPC valve

60

A (EPC valves

60

a

,

60

b

in the drawing) have been described. However, in another embodiment, a first PPC valve

75

similar to the PPC valve

50

in the first embodiment may be used instead of the electric operation lever

71

, as shown in FIG.

19

. In this case, the first PPC valve

75

is disposed inside a driver's cab and the first manipulation section

35

a

of a wireless installation is disposed outside the driver's cab as in the case of the second embodiment.

Referring to

FIG. 19

, when manipulating an additional EPC valve

60

A inside a driver's cab, the first PPC valve

75

is manipulated, thereby causing the PPC-valve pressure reducing valve (not shown) to produce pilot pressure oil and to output the pilot pressure oil through the first shuttle valve

30

A to the operating valve for the attachment. Likewise, in a case of manipulating an additional EPC valve

60

A outside a driver's cab, the operating switch provided in the first manipulation section

35

a

is manipulated, thereby causing the corresponding EPC valves

60

a

,

60

b

to produce pilot pressure oil having a pressure according to a quantity of the operation and to output the pilot pressure oil through the first shuttle valve

30

A to the operating valve for the attachment.

In the second embodiment, while the manipulation section

35

, first manipulation section

35

a

and electric operation lever

71

are each arranged to output a control command according to a quantity of the operation, a switch for ON-OFF switching may be used. Also, in this case, the EPC valve

60

may be an electromagnetic valve for ON-OFF operation.

The second embodiment can be provide the following advantages.

Like the first embodiment, the hydraulic apparatuses are integrated to constitute the first oil pressure signal output device

1

A, so that it becomes possible to reduce the occupied area by the hydraulic apparatuses, thereby to secure a larger space available for apparatuses or devices other than the hydraulic apparatuses.

Further, the first oil pressure signal output device

1

A is provided with a hydraulic pump passage and a tank passage, which communicate with each other, between a set of EPC valves

60

for hydraulic apparatuses as standard equipment and the adjacent EPC valve

60

A for an additional hydraulic apparatus. For this reason, in additionally installing an attachment, it is not required to provide a pump line, tank line and the like, which are used for the installation of the additional hydraulic apparatus, and therefore space-saving additional installation can be realized. This makes it possible to mount an oil pressure signal output device capable of manipulating an additional attachment easily and compactly, and to improve the ease of construction and maintainability, even at the time of and after the shipment of working vehicles.

Referring now to

FIGS. 20-22

, a second oil pressure signal output device

1

B of the third embodiment is described.

FIG. 20

is a sectional view of the EPC valves (a sectional view taken along the line B

2

—B

2

of FIG.

21

), which is equivalent to FIG.

6

.

FIG. 21

is a partial front outline view, which is equivalent to a side view taken from the direction indicated by the arrow Y of FIG.

2

.

FIG. 22

is a sectional view of the EPC valves (a sectional view taken along the line C

2

—C

2

of FIG.

21

), which is equivalent to FIG.

7

. Now, it should be noted that

FIG. 22

represents the structure inside the EPC valves

60

for brevity.

The second oil pressure signal output device

1

B shown in

FIGS. 20

,

21

and

22

is a result of adding an additional second EPC valve

60

D for manipulating another additional hydraulic apparatus to the first oil pressure signal output device

1

A described in the second embodiment. More specifically, in the second oil pressure signal output device

1

B of the embodiment, there are attached: an additional first EPC valve

60

A to the side surface of the EPC valve body

61

in the oil pressure signal output device

1

of the first embodiment on the right of the drawing; an additional second EPC valve

60

D to the side surface of the EPC valve body

61

on the left of the drawing; a right-side cover

63

b

to the right side surface of the first EPC valve

60

A; and a left-side cover

63

a

to the left side surface of the second EPC valve

60

D. The second EPC valve

60

D is arranged to be the same as the first EPC valve

60

A and to actuate in the same way. This makes it possible to additionally mount two operating valves for activating additional hydraulic apparatuses to the first embodiment.

In the case of the above second oil pressure signal output device

1

B, the additional first EPC valves

60

A for manipulating new additional hydraulic apparatuses are added on both side surfaces of the oil pressure signal output device

1

in the first embodiment, one for each additional hydraulic apparatus. However, it is not necessary to be so limited, and a plurality of such additional first EPC valves

60

A may be provided on at least one side surface. The added first EPC valve

60

A can be controlled by a manipulation section similar to that of the second embodiment (the manipulation section

70

inside/outside a driver's cab).

Also, in this case, the first EPC valves

60

A for an additional apparatuses to be provided on both the side surfaces of the standard-equipment EPC valves

60

are provided with an oil pressure pump passage and a tank passage, which communicate with each other, between the adjacent EPC valve

60

and the first EPC valves, so that it is not required to a pump line, a tank line and the like for the first EPC valve

60

A used for the additional apparatus. This makes it possible to easily and compactly mount an oil pressure signal output device capable of manipulating a new attachment even at the time of and after the shipment in the same way, thereby improving the ease of construction or maintainability and securing a larger space available for setting apparatuses or devices other than the hydraulic apparatuses.

While an example where a shuttle valve (See

FIG. 23A

) is used as a selecting output means is shown in the above-described embodiments, it is not necessary to be so limited and the device may be constituted by a combination of a plurality of check valves, for example, as shown in FIG.

23

B.

As described above, the invention can provide the following advantages.

The oil pressure signal output device has a PPC valve and EPC valves integrated, and a pump passage and tank passage, which communicate with each other, provided on the side surface of the EPC valve body. When providing an additional EPC valve; an additional EPC valve can be mounted on the EPC valve body side surface, a pump passage and a tank passage of the additional EPC valve communicate with a pump passage and a tank passage of the EPC valve body side surface respectively, so that no additional piping is required. Therefore, it is possible to reduce a space for the hydraulic apparatuses, to facilitate the piping work and to improve the ease of construction. Further, it is possible to provide an oil pressure signal output device capable of accommodating the addition of a new attachment easily even after shipment of vehicles.

Number	Date	Country
10204929	Aug 1998	JP
2000-147407	May 2002	JP

Oil pressure signal output device

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Term Extension

Abstract

Description

Claims

Foreign Referenced Citations (2)