Information
-
Patent Grant
-
6564480
-
Patent Number
6,564,480
-
Date Filed
Tuesday, November 28, 200023 years ago
-
Date Issued
Tuesday, May 20, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Pezzuto; Robert E.
- Petravick; Meredith
Agents
-
CPC
-
US Classifications
Field of Search
US
- 037 906
- 037 413
- 037 348
- 037 347
- 414 698
- 414 699
- 033 1 N
- 033 1 PT
-
International Classifications
-
Abstract
In a working apparatus, a recessed portion is formed at an end surface of a pin provided at a boom to house a case of an angle sensor in the recessed portion. A flange is projected from the case along the direction of the axis of an input shaft so as to enclose the input shaft outside the movement range of a lever. By projecting the flange further out than the distance over which the input axis projects out, the protection provided by the flange for the input shaft is enhanced.
Description
This application is a continuation of PCT International Application No.PCT/JP00/01997 filed Mar. 30, 2000.
INCORPORATION BY REFERENCE
The disclosures of the following priority applications are herein incorporated by reference: Japanese Patent Application No. 11-88797 Japanese Patent Application No. 11-88798 Japanese Patent Application No. 11-113794
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a working apparatus for construction machine and, more specifically, it relates to an working apparatus provided with an angle sensor that measures the relative rotating angles of members rotatably linked to each other such as the boom and the arm of a hydraulic shovel.
2. Related Art
In a construction machine such as a hydraulic shovel, an angle sensor is provided in the working apparatus. In such a working apparatus, the boom and the arm are linked with each other via a pin so as to allow them to rotate relative to each other, and their relative angles are detected by the angle sensor mounted at a side surface of the boom. The angle sensor, which comprises an input shaft, a sensor unit that detects the rotating angle of the input shaft and a case housing the input shaft and the sensor unit. The input shaft is linked or connected to the arm via a lever. When the arm is engaged in rotation relative to the pin, the input shaft at the angle sensor is caused to rotate via the lever which interlocks with the rotation of the arm. The rotating angle of the input shaft is detected by the sensor unit, and the relative angle of the arm is obtained based upon the detected value.
The angle sensor is mounted at the side surface of the boom so as to project out from the side surface, with one end of the lever linked to the input shaft of the angle sensor and the other end of the lever secured to a side surface of the arm. As a result, problems arise during operation in that the angle sensor and the lever projecting out to a side of the boom come into contact with soil and the like and that the angle sensor and the lever tend to interfere with objects in the vicinity.
These problems necessitate a large protective cover to be provided to protect the angle sensor from coming into contact with soil and the like. In addition, when soil or the like comes in contact with the lever, there is a risk of the angle sensor becoming damaged due to the impact to which the input shaft of the angle sensor is subjected via the lever.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a working apparatus for construction machine that prevents the angle sensor provided at the boom or the like from becoming damaged readily by soil and the like.
In order to achieve the object described above, the working apparatus for construction machine according to the present invention comprises a first member, a second member rotatably linked with the first member via a linking member provided as an integrated part thereof and an angle sensor having an input shaft driven to rotate by the first member and a sensor unit that detects the rotating angle of the input shaft, and a recessed portion is formed at an end surface of the linking member along the axial direction thereof to house, at least, an angle sensor case in its entirety within the recessed portion.
Thus, the distance by which the angle sensor projects out from the end surface of the linking member along the axial direction thereof is reduced, thereby reducing the risk of falling soil or the like coming into contact with the angle sensor during operation. In particular, by housing the entire angle sensor inside the recessed portion, soil or the like is not allowed to come into contact with the angle sensor readily, and thus, the protective cover can be omitted.
In addition, a communicating member that links the first member and the input shaft so as to drive the input shaft to rotate by interlocking with the rotation of the first member is provided, (a) a recessed portion is formed at an end surface of the linking member along the axial direction to house the case in the recessed portion and (b) a projected portion projecting out along the axial direction of the input shaft is provided at an end surface of the case so as to enclose the input shaft outside of the movement range of the communicating member. By forming such a projected portion, it is ensured that the input shaft is protected by the projected portion even when soil, rocks and the like come falling down.
Furthermore, by projecting the projected portion of the case out from the end surface thereof along the axial direction further than the distance over which the input shaft projects out, an improvement is achieved in the protective function of the projected portion in protecting the input shaft. By providing an input shaft protective cover, a further improvement is achieved in the degree of protection provided for the input shaft, and also, by securing the input shaft protective cover and the angle sensor to the linking member with a common fastener, the number of required parts can be reduced.
By forming a passage for a wiring harness in the angle sensor case, the wiring harness can be drawn out of the recessed portion from the sensor unit with ease. Alternatively, it is acceptable to provide a seal member that seals the external circumferential surface of the case and the internal circumferential surface of the recessed portion at the external circumferential surface, a groove formed at the external circumferential surface of the case and a passage for the wiring harness formed at the seal member at a position aligned with the position of the groove.
Moreover, by providing a communicating member linking the first member and the input shaft and allowing the link between the first member and the input shaft to become released when an external force equal to or exceeding a specific level is applied to the communicating member, it is possible to ensure that no excessive impact force is applied to the input shaft of the angle sensor, thereby increasing the service life of the angle sensor. For instance, the link may be released by allowing the end of the communicating member slidably inserted in a hole at the input shaft to slip out of the hole or by causing the communicating member to break, when an external force equal to or exceeding the specific level is applied.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
illustrates a schematic structure of a hydraulic shovel;
FIG. 2
is a sectional view illustrating the angle sensor in a mounted state in a first embodiment;
FIG. 3
illustrates the angle sensor
21
in
FIG. 2
in further detail;
FIG. 4A
is a front view of the case
21
a;
FIG. 4B
is a bottom view of the case
21
a
in
FIG. 4A
;
FIG. 4C
is a sectional view through B
1
—B
1
in
FIG. 4A
;
FIG. 5A
illustrates a portion of the pin
22
where the angle sensor is provided in a second embodiment, viewed from a side of the boom;
FIG. 5B
is a sectional view through X
1
—X
1
in
FIG. 5A
;
FIG. 6
illustrates a third embodiment;
FIG. 7
presents a sectional view of the pin
22
provided in a fourth embodiment;
FIG. 8
illustrates the angle sensor
21
in
FIG. 7
in further detail;
FIG. 9
illustrates a structure achieved by providing a flange
33
over the entire circumference of the input shaft
21
b;
FIG. 10
illustrates how the harness
216
is mounted;
FIG. 11A
is a front view of the case
21
a
A;
FIG. 11B
is a bottom view of the case
21
a
A in
FIG. 11A
;
FIG. 11C
is a sectional view through C—C in
FIG. 11A
;
FIG. 12A
presents a perspective of the case
21
a
B which is a variation of the case
21
a
A;
FIG. 12B
is a sectional view illustrating the case
21
a
B in detail;
FIG. 13A
is a plan view of the seal member
34
;
FIG. 13B
is a sectional view of
FIG. 13A
;
FIG. 14
is an enlarged view of the area in the vicinity of the pin
22
in the front operating apparatus
6
in
FIG. 1
;
FIG. 15
illustrates the linking area in
FIG. 14
, viewed from direction B
3
;
FIG. 16
illustrates the angle sensor
21
in
FIG. 15
in detail;
FIG. 17
is a sectional view illustrating the angle sensor
21
in
FIG. 16
in detail;
FIG. 18A
shows the angle sensor
21
and the lever
23
viewed from a side of the boom;
FIG. 18B
illustrates the angle sensor
21
and the lever
23
, with the protective cover
30
C in
FIG. 18A
removed;
FIG. 19A
illustrates the lever
23
in a state in which a load F
1
is applied;
FIG. 19B
illustrates the lever
23
in a state in which a load F
2
is applied;
FIG. 20A
illustrates the lever
23
in a state in which an external force F is applied;
FIG. 20B
shows the various dimensions of the lever
23
having undergone deformation;
FIG. 20C
shows the dimensions of the linking area where the lever
23
and the input shaft
21
b
are linked;
FIG. 21A
presents another example in which the link can be released, illustrating a state in which no impact load is applied to the lever
70
; and
FIG. 21B
illustrates a state in which the load F
2
is applied in the other example of link which can be released.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following is an explanation of the preferred embodiments of the present invention, given in reference to the drawings.
First Embodiment
In
FIG. 1
illustrating a schematic structure of a hydraulic shovel, an upper rotating body
2
is provided at a lower traveling body
1
via a rotating mechanism. A front working apparatus
6
comprising a boom
3
, an arm
4
and a bucket
5
is provided at the upper rotating body
2
. The boom
3
, the arm
4
and the bucket
5
are rotatably linked so as to allow them to rotate relative to the pins
12
,
22
and
32
.
FIG. 2
shows an angle sensor in a mounted state at the operating apparatus according to the present invention in a sectional view of the essential portion of the operating apparatus through line I—I in FIG.
1
. As explained earlier, the boom
3
and the arm
4
are rotatably connected with each other via the front pin
22
. The pin
22
is secured to the boom
3
with a bolt
24
and the arm
4
is rotatably linked to the pin
22
. At an end surface of the pin
22
, a recessed portion
22
a
having a circular cross-sectional shape is formed coaxially to the center of the axis of the pin
22
to house an angle sensor
21
. The angle sensor
21
comprises a case
21
a
, an input shaft
21
b
and a sensor unit
21
c
. The case
21
a
of the angle sensor
21
is housed inside the recessed portion
22
a
so as to allow the input shaft
21
b
to project out from the end surface of the pin
22
and is secured to the pin
22
through a screw
26
a.
While it is desirable to form the recessed portion
22
a
coaxially to the pin
22
in order to assure a high degree of detection accuracy, the recessed portion
22
a
does not need to be perfectly coaxial with the pin
22
as long as a sufficient degree of accuracy is assured with regard to the coaxial alignment of the input shaft
21
b
of the angle sensor
21
housed in the recessed portion
22
a
and the pin
22
.
One end of a lever
23
is linked to the input shaft
21
b
and the other end of the lever
23
is secured to the arm
4
through a bolt
25
. Thus, when the angle of the arm
4
changes, i.e., when the arm
4
is rotated by using the pin
22
as the fulcrum, the input shaft
21
b
of the angle sensor
21
is driven to rotate by the lever
23
secured to the arm
4
.
FIG. 3
is a sectional view illustrating the angle sensor
21
in detail. The input shaft
21
b
is mounted at the case
21
a
via bearings
212
. Above the bearings
212
in the figure, a seal
213
which prevents water, oil, mud or the like from entering the case is provided. Reference number
214
is a resistor secured to the input shaft
21
b
, which rotates together with the input shaft
21
b
, and a wiper
215
is provided at a position facing opposite the resistor
214
. The sensor unit
21
c
(see
FIG. 2
) mentioned earlier is constituted of the resistor
214
and the wiper
215
. When the input shaft
21
b
is driven to rotate by the lever
23
, the resistor
214
engages in rotation, causing the positions of the resistor
214
and the wiper
215
relative to each other to change, which results in a change in the output voltage. This change occurring in the output voltage is communicated to a controller
29
of the hydraulic shovel by a harness
216
connected to the wiper
215
, and a change in the angle of the arm
4
relative to the boom
3
is calculated at the controller
29
. A seal member
217
such as an O-ring is provided at a side surface of the case
21
a
to prevent water and the like from entering the bottom portion of the recessed portion
22
a.
The harness
216
is drawn out of the recessed portion
22
a
via a passage (grooves
41
and a hole
42
to be detailed later) extending from the bottom of the case
21
a
through the case
21
a
and is connected to the controller
29
. FIGS.
4
A˜
4
C illustrate the case
21
a
, with
FIG. 4A
presenting a front view of the case
21
a
,
FIG. 4B
showing the case
21
a
in
FIG. 4A
viewed from the lower side of the figure and
FIG. 4C
presenting a sectional view through B
1
—B
1
in FIG.
4
B. Inside the case
21
a
formed in a roughly cylindrical shape, a housing portion
211
a
for the seal
213
, housing portions
211
b
and
211
c
for the bearings
212
, a housing portion
211
d
for the resistor
214
and a housing portion
211
e
for the wiper
215
are individually formed. An O-ring groove
40
is formed as a recessed passage at the external circumference of the case
21
a
. Above and below the O-ring groove
40
, the grooves
41
running along the axial direction are formed, and the hole
42
communicating between the upper and lower grooves
41
is formed through the inside of the O-ring groove
40
. The harness
216
is threaded from the lower groove
41
to the upper groove
41
via the hole
42
, as indicated by the 2-point chain line in
FIG. 4C
, to be connected to the controller
29
as shown in FIG.
3
.
As described above, in this embodiment having the case
21
a
of the angle sensor
21
provided inside the recessed portion
22
a
formed at the end surface of the pin
22
along the axial direction, the distance over which the angle sensor
21
projects out from the boom side surface is reduced, thereby reducing the risk of soil, rocks and the like coming into contact with the angle sensor
21
during operation.
Second Embodiment
FIGS. 5A and 5B
illustrate the second embodiment of the present invention, with
FIG. 5A
showing the pin
22
over the area where the angle sensor is provided viewed from a side of the boom and
FIG. 5B
presenting a sectional view through X
1
—X
1
in FIG.
5
A. In the embodiments, a protective cover
30
A is provided at a side of the input shaft
21
b
. The protective cover
30
A, which is mounted at an end surface of the pin
22
with a bolt
26
B, achieves a shape which allows it to cover the case
21
a
and the input shaft
21
b
of the angle sensor
21
in their entirety viewed from a side of the boom
3
. The angle sensor
21
is protected by the protective cover
30
A in this manner, so that soil and the like are prevented from coming into contact with the angle sensor
21
from a side of the boom
3
.
Since the entire case
21
a
is housed inside the recessed portion
22
a
and the input shaft
21
b
alone is projected out to the side (the upper side in the figure) from the pin end surface
22
b
in this embodiment, too, the distance h over which the protective cover
30
A projects out can be reduced compared to the prior art.
Third Embodiment
In
FIG. 6
, illustrating the third embodiment of the present invention, the entire angle sensor
21
including the input shaft
21
b
is housed inside the recessed portion
22
a
of the pin
22
. By housing the entire angle sensor
21
inside the recessed portion
22
a
in this manner, only the lever
23
is projected out of a side of the boom, thereby making it possible to dispense with a protective cover for protecting the angle sensor
21
.
Fourth Embodiment
In
FIGS. 7 and 8
illustrating the fourth embodiment of the present invention, sectional views of the pin
22
are presented as in FIG.
2
.
FIG. 8
presents a more detailed sectional view which includes the angle sensor
21
. A case
21
a
A of the angle sensor
21
is housed inside the recessed portion
22
a
as in
FIG. 2
, and is secured to the in
22
with a screw (not shown) (the screw
26
A in FIG.
2
).
A flange
218
projects out at an end surface of the case
21
a
A, and by securing the flange
218
to the end surface
22
b
of the pin
22
with a bolt
26
C, the angle sensor
21
is mounted at the pin
22
. A protective cover
30
B, which protects the input shaft
21
b
from impact from soil and the like, is mounted as an integrated part of the angle sensor
21
at the pin
22
with the bolt
26
C.
One end of the lever
23
is linked to the input shaft
21
b
projecting out from the end surface
22
b
of the pin
22
, and the other end of the lever
23
is secured to the arm
4
with a bracket
27
. Reference number
28
indicates a bolt used to mount the bracket
27
at the arm
4
. An upper end surface
219
of the input shaft
21
b
in the figure projects out to the side (the upper side in the figure) from the end surface
22
b
of the pin
22
.
As shown in
FIG. 7
, one end of the lever
23
is secured to the arm
4
with a bracket
27
, and thus, the lever
23
causes the input shaft
21
b
of the angle sensor
21
to rotate when the arm
4
is rotated. The flange
218
is formed in an arc shape so as to remain outside of the movement range of the lever
23
. By forming the flange
218
in an arc shape in this manner, the distance over which the protective cover
30
B projects out from the side surface of the boom
3
(h
1
in
FIG. 8
) can be minimized. Namely, if the flange
218
is formed in a toroidal shape as a flange
33
in
FIG. 9
is, the input shaft
21
b
must be made to project out further than the flange
33
with the lever
23
provided further to the side (further toward the upper side in the figure) relative to the flange
33
. As a result, there is a problem in that the distance h
2
(>h
1
) over which the protective cover
30
C projects out from the side surface of the boom
3
becomes large. However, in the embodiment described above, the projecting distance can be minimized compared to that in the structure shown in
FIG. 9
, to prevent falling objects such as soil and rocks from coming into contact with the angle sensor
21
readily.
In addition, since the flange
218
projects out so as to enclose the input shaft
21
b
, the input shaft
21
b
is protected from falling soil and rocks along the pin end surface
22
b
(along the direction indicated by the arrow AL in
FIG. 8
) without having to provide the protective cover
30
B. Thus, by setting the end surface
219
of the input shaft
21
b
further toward the pin relative to an end a surface
220
of the flange
218
as illustrated in
FIG. 10
, it becomes possible to dispense with the protective cover
30
B in FIG.
8
. The boom pin (the pin
12
in
FIG. 1
) which is not likely to be impacted by soil from the direction of the pin end surface, in particular, does not require the protective cover
30
B in this structure.
Next, a specific method for mounting the harness
216
is explained. As illustrated in
FIG. 10
, the harness
216
is drawn out of the recessed portion
22
a
via a passage (grooves
41
and a hole
42
to be detailed later) extending from the bottom portion of the case
21
a
A through the case
21
a
A and is connected to the controller
29
.
FIGS. 11A
,
11
B and
11
C show the case
21
a
A, with
FIG. 11A
presenting a front view of the case
21
a
A,
FIG. 11B
showing the case
21
a
A in
FIG. 11A
viewed from the lower side of the figure and
FIG. 11C
presenting a sectional view through C—C in
FIG. 11A. A
flange
218
formed as shown in FIGS.
11
A˜
11
C is provided at the upper end of the case, and the case
21
a
A is identical to the case
21
a
shown in FIGS.
4
A˜
4
C except for the flange
218
.
At positions above and below the O-ring groove
40
, the grooves
41
extending along the axial direction are formed, and the hole
42
communicating between the upper and lower grooves
41
is formed through the inside of the O-ring groove
40
. It is to be noted that the upper groove
41
in the figures is formed at the lower surface of the flange
218
as well as at a side surface of the case
21
a
A. The portion of the groove
41
formed at the lower surface of the flange
218
extends along the direction of the radius of the case
21
a
A. The harness
216
is provided to extend from the lower groove
41
to the upper groove
41
via the hole
42
as indicated by the 2-point chain line and is drawn out of a flange
218
to be connected to the controller
29
, as illustrated in FIG.
10
.
A case
21
a
B shown in
FIGS. 12A and 12B
is a variation of the case
21
a
A, with
FIG. 12A
presenting a perspective of the case
21
a
B and
FIG. 12B
presenting a sectional view illustrating the case
21
a
B in detail. Inside the case
21
a
B, which is formed in a roughly cylindrical shape as is the case
21
a
A, a housing portion
211
a
for an oil seal
213
, housing portions
211
b
and
211
c
for the bearings
212
, a housing portion
211
d
for the resistor
214
and a housing portion
211
e
for the wiper
215
are individually formed. As illustrated in
FIG. 12A
, a seal member
34
is provided at the case
21
a
B.
FIGS. 13A and 13B
respectively present a plan view and a sectional view of the seal member
34
. The seal member comprises an O-ring portion
34
a
and the cable passing portion
34
b
that constitute an integrated component. A hole
34
c
through which a cable
216
passes is formed at the cable passing portion
34
b.
At the external circumferential surface of the case
21
a
B shown in
FIGS. 12A and 12B
, an O-ring groove
40
, in which the seal member
34
is placed, and the groove
43
extending along the axial direction in which the cable
216
is placed are formed. When mounting the seal member
34
in the groove
40
, the cable passing portion
34
b
of the seal member
34
is set at the groove
43
. The groove
43
is formed along the axial direction at the side surface of the case
21
a
B and along the direction of the radius (the horizontal direction in
FIG. 12B
) of the case
21
a
B at the lower surface of the flange
218
. The cable
216
is provided along the groove
43
from the bottom portion of the case
21
a
B, passes through the hole
34
c
at the cable passing portion
34
b
and is drawn out upward. The gap between the cable
216
and the hole
34
c
is sealed by using a molding material or the like.
Fifth Embodiment
Next, the fifth embodiment is explained in reference to FIGS.
14
˜
20
C. The fifth embodiment is characterized by the connection between the lever
23
and the input shaft
21
b
.
FIG. 14
is an enlarged view of the vicinity of the pin
22
at the front working apparatus
6
in FIG.
1
and
FIG. 15
shows the linking portion in
FIG. 14
viewed from direction B
3
. The pin
22
is secured to the boom
3
, and the arm
4
, which is rotatably linked to the pin
22
, is caused to rotate as a hydraulic cylinder
7
expands and contracts. That change in the angle of arm
4
relative to the boom
3
is detected by the angle sensor
21
provided at the pin
22
. In
FIG. 16
, which shows the angle sensor
21
in
FIG. 15
in detail, a recessed portion
22
a
having a substantially circular cross sectional shape is formed at an end surface of the pin
22
coaxially to the center of the axis of the pin
22
and the angle sensor
21
is provided in the recessed portion
22
a
as described earlier.
The angle sensor
21
in
FIG. 16
is provided with the case
21
a
B in
FIGS. 12A and 12B
. The case
21
a
B is mounted at the pin
22
with the bolt
26
C. Reference number
30
D indicates a protective cover which protects the input shaft
21
b
from the impact of soil and the like, and the protective cover
30
D is mounted at the pin
22
as an integrated part of the angle sensor
21
with the bolt
26
C. As explained earlier, while it is desirable to form the recessed portion
22
a
coaxially to the pin
22
, in order to achieve a higher degree of detection accuracy, the recessed portion
22
a
does not need to achieve perfect coaxial alignment with the pin
22
as long as the input shaft
21
b
of the angle sensor
21
provided inside the recessed portion
22
a
and the pin
22
achieve coaxial alignment within a specific range, i.e., as long as a sufficient degree of accuracy is assured.
One end of the lever
23
is linked to the input shaft
21
b
projecting out from the end surface
22
b
of the pin
22
, and the other end of the lever
23
is secured to the arm
4
with the bracket
27
. It is to be noted that the link between the input shaft
21
b
and the lever
23
is to be detailed later. The lever
23
, which is constituted of an elastic material such as a piano wire (the following explanation is given on the assumption that the lever
23
is constituted of a piano wire) is formed to extend along a path close to the side surfaces of the boom
3
and the arm
4
, as shown in FIG.
16
. By providing the lever
23
close to the side surfaces of the boom
3
and the arm
4
in this manner, the risk of impact from soil, rocks and the like occurring during operation can be reduced. When the angle of the arm
4
is changed, i.e., when the arm
4
is rotated by using the pin
22
as the fulcrum, the input shaft
21
b
of the angle sensor
21
is driven to rotate by the lever
23
secured to the arm
4
.
FIG. 17
is a sectional view illustrating the angle sensor
21
in detail. The input shaft
21
b
is mounted at the case
21
a
B via bearings
212
. A hole H substantially perpendicular to the axial direction is formed at the input shaft
21
b
, and by inserting an end of the lever
23
at the hole H the input shaft
21
b
and the lever
23
are linked. The diameter of the hole H is larger than the wire diameter of the lever
23
to allow the lever
23
to slide relative to the hole H along the horizontal direction in the figure.
Above the bearings
212
in the figure, oil seals
213
for preventing entry of water, oil, mud and the like into the case are provided. Reference number
214
indicates a resistor secured to the input shaft and caused to rotate together with the input shaft, and a wiper
215
is provided at a position facing opposite the resistor
214
. The sensor unit
21
c
mentioned earlier is constituted of the resistor
214
and the wiper
215
. When the input shaft
21
b
is driven to rotate by the lever
23
, the resistor
214
also rotates, which changes the positions of the resistor
214
and the wiper
215
relative to each other to change the output voltage from the resistor
214
. This change in the output voltage is communicated to the controller
29
of the hydraulic shovel through a cable
216
connected to the wiper
215
, and the change in the angle of the arm
4
relative to the boom
3
is calculated at the controller
29
.
The seal member
34
mentioned earlier (see
FIGS. 13A and 13B
) is provided at the side surface of the case
21
a
B to prevent entry of water and the like into the bottom portion of the recessed portion
22
a
. The cable
216
passes through the case
21
a
B and the seal member
34
, is drawn out of the sensor through the flange
218
and is connected to the controller
29
.
FIGS. 18A and 18B
show the angle sensor
21
and the lever
23
viewed from a side of the boom.
FIG. 18B
shows them in a state in which the protective cover
30
D is removed. The left end of the lever
23
is secured to the arm
4
with the bracket
27
, and when the arm
4
is rotated and its angle changes, the lever
23
causes the input shaft
21
b
of the angle sensor
21
to rotate. The rotating range of the arm
4
over which the arm
4
rotates relative to the boom
3
is limited to a specific angle range by the stroke of the hydraulic cylinder
7
shown in
FIG. 14 and
, in the example presented in
FIG. 18B
, the lever
23
interlocking with the arm
4
rotates over the range A
1
˜A
2
(±α°) indicated by the 2-point chain line. It is to be noted that the lever
23
is set at A
1
when the state of the arm
4
is as indicated by the solid line in
FIG. 14
, whereas the lever
23
is set at A
2
when the arm
4
has rotated as indicated by the dotted line
4
.
As described above, the lever
23
rotates within the range A
1
˜A
2
, and accordingly, the flange
218
is formed in an arc shape to ensure that the lever
23
and the flange
218
do not interfere with each other, as illustrated in FIG.
18
B. By projecting out the arc-shaped flange
218
so as to enclose the input shaft
21
b
in this manner, the input shaft
21
b
is protected from falling soil, rocks and the like along the end surface of the pin
22
(along the direction indicated by the arrow AL in
FIG. 18B
) even without the protective cover
30
C. It is not necessary to provide the protective cover
30
D especially for the boom pin (pin
12
in
FIG. 1
) which is less likely to impact with soil from the direction of the end surface of the pin
22
.
The embodiment having the lever
23
constituted of an elastic material such as piano wire and slidably inserted at the hole H of the input shaft
21
b
achieves the following advantages. Namely, the lever
23
undergoes elastic deformation if it is struck by soil or the like to slip out of the hole H, thereby releasing the link between the lever
23
and the input shaft
21
b
. As a result, the input shaft
21
b
can not be subjected to an excessive degree of impact.
FIGS. 19A and 19B
conceptually illustrate the lever
23
to which loads F
1
and F
2
along the side surface of the boom
3
applied when the lever
23
comes into contact with soil. The load F
1
in
FIG. 19A
is relatively small, whereas
FIG. 19B
presents an example in which a larger load F
2
(F
2
>F
1
) is applied to the lever
23
. In
FIG. 19A
, indicated by the dotted line is the lever
23
in a normal state in which no impact load is applied to it. It is to be noted that the explanation is given on the assumption that the lever
23
is constituted of a linear piano wire.
In the example presented in
FIG. 19A
, the lever
23
becomes deformed to bend downward due to the load F
1
(deformation quantity Δ), and this deformation causes the input shaft
21
b
to rotate counterclockwise by an angle θ
1
. In addition, the deformation of the lever
23
reduces the length of the lever
23
over which it is inserted at the hole H. In the example presented in
FIG. 19B
, with the larger load F
2
applied to the lever
23
, the deformation quantity Δ of the lever
23
increases, causing the input shaft
21
b
to rotate counterclockwise by a larger angle θ
2
(>θ
1
) and, as a result, the length of the lever
23
inserted at the hole H is greatly reduced. If a load even larger than F
2
is applied to the lever
23
, i.e., if (impact load)>F
2
, the deformation quantity Δ of the lever
23
and the rotating angle of the input shaft
21
b
further increase, to result in the lever
23
slipping out of the hole H as indicated by the two-point chain line, thereby releasing the link between the lever
23
and the input shaft
21
b.
If a strong lever constituted of a steel plate, for instance, as in the prior art is secured to the input shaft
21
b
, the link between the input shaft
21
b
and the lever is not released even when an excessive load is applied to the lever, resulting in a great impact force being applied to the input shaft
21
b
. This presents a risk of the bearings
212
supporting the input shaft
21
b
and the sensor unit
21
c
becoming damaged when the lever comes in contact with rocks and the like. However, in this embodiment, in which the link between the lever
23
and the input shaft
21
b
is released if an excessive load is applied to the lever
23
as described above, no excessively large impact force is applied to the input shaft
21
b
and an increase in the service life of the angle sensor
21
is achieved.
The level of the load required for the lever
23
to slip out of the hole H at the input shaft
21
b
is determined in conformance to the elastic coefficient of the piano wire constituting the lever
23
, the diameter of the piano wire, the length of the lever
23
over which it is inserted at the hole H and the like, and should be set as appropriate in correspondence to the level of the load tolerated by the angle sensor
21
. For instance, by reducing the diameter of the piano wire to allow for easy deformation or by reducing the length over which the lever is inserted at the hole, the lever
23
is allowed to slip out of the hole H even at a small load, to reduce the degree to which the angle sensor
21
is affected.
An example of the method for setting the dimensions of the lever
23
is now explained in reference to FIGS.
20
A˜
20
D.
FIG. 20A
illustrates the lever
23
, whose one side is fixed and the other side is a free, to which an external force F applied at the center thereof. The deflection Δ of the lever
23
occurring in this situation is the largest at a position distanced from the free end by a distance L
2
. The reactive force R applied to the free end is calculated through the following formula (3), and the dimensions of the lever
23
should be set by ensuring that the lever
23
becomes disengaged from the input shaft
21
b
before the reactive force R exceeds the load limit Sf of the angle sensor
21
. In addition, L
2
and Δ are calculated through formulae (1) and (2).
L
2
=(1{square root over (5)})·
L
(1)
Δ=(
F·L
3
)/(48{square root over (5)}
·E·I
) (2)
R
=(5/16)·
F
(3)
It is to be noted that d represents the wire diameter of the lever
23
, L represents the full length of the lever
23
, E represents the longitudinal elastic coefficient of the lever
23
and I represents the sectional secondary moment of the lever
23
.
FIG. 20B
presents the various dimensions resulting from a deformation of the lever
23
due to the deflection Δ and
FIG. 20C
shows the dimensions of the linking portion where the lever
23
and the input shaft
21
b
are linked. The individual dimensions L
3
˜L
5
in
FIG. 20B
are calculated through the following formulae (4)˜(6);
L
3={square root over ((
L−L
2)
2
+Δ
2
)} (4)
L
4={square root over ((
L
2
2
+Δ
2
))} (5)
L
5
=L−L
3
−L
4 (6)
Namely, by ensuring that (L
5
+a
1
) is larger than “a” when the deflection Δ has occurred, the lever
23
is allowed to disengage from the input shaft
21
b
. For instance, the wire diameter d of the lever
23
may be determined in correspondence to the full length L of the lever
23
and the deflection Δ. By setting the full length L and the deflection Δ of the lever
23
at specific values and using those values for L and Δ in the following formula (7) which is obtained from formula (2), for substitution, the cross sectional secondary moment I is calculated. The cross sectional secondary moment I thus calculated is then used for substitution in relational expression (8) expressing the relationship between the wire diameter d and I, and then the wire diameter d is calculated through a reverse operation. Alternatively, the full length L of the lever
23
may be determined in correspondence to the wire diameter d and the deflection Δ of the lever
23
.
I
=(
F·L
3
)/(48{square root over (5)}
·E
·Δ) (7)
I
=(π/64)·
d
4
(8)
While an explanation is given in reference to the embodiment above on an example in which the link between the lever
23
and the input shaft
21
b
is released, the link between the arm
4
and a lever
70
may be released as illustrated in
FIGS. 21A and 21B
instead.
FIG. 21A
illustrates a normal state in which the lever
70
constituted of an arm link portion
70
a
, an input shaft securing portion
70
b
and a shaft portion
70
c
formed from piano wire or the like is not subjected to any impact load. An elongated hole
701
is formed at the arm link portion
70
a
. A connector pin
72
provided at the arm
4
is connected at the elongated hole
701
and the lever
70
and the arm
4
are linked each other. The input shaft securing portion
70
b
is secured to the input shaft
21
b
with a bolt
71
.
If the load F
2
(the force working along the side surface of the boom
3
) is applied to the shaft portion
70
c
of the lever
70
as shown in
FIG. 21B
, the shaft portion
70
c
becomes deformed to bend out downward to cause the input shaft
21
b
to rotate counterclockwise by an angle θ
4
and to tilt the arm link portion
70
a
by an angle θ
3
relative to the horizontal direction. While the elongated hole
701
of the arm link portion
70
a
is still connected with the pin
22
in this state, the connection of the elongated hole
701
and the pin
72
, i.e., the link between the lever
70
and the arm
4
, is released, as indicated by the two-point chain line in
FIG. 21B
if a load any larger than F
2
is applied.
Furthermore, the mechanical strength of the lever
23
may be set so as to cause the lever
23
to break (e.g., to undergo plastic deformation or rupture) if a load equal to or exceeding a specific level is applied to the lever
23
to release the link. While it is necessary to replace the broken lever with a new lever, the lever
23
can be reused if the lever
23
is allowed to slip out of the hole H through elastic deformation, as described earlier. However, by allowing the lever
23
to rupture to release the link, the need to form an end of the lever
23
in such a manner that it can slide relative to the input shaft
21
b
is eliminated.
While an explanation is given above in reference to the embodiments on an example in which the present invention is adopted in an angle sensor that detects the angles of the boom
3
and the arm
4
relative to each other, the present invention may be adopted in an angle sensor that detects the boom angle representing the angles of the upper rotating body
1
and the boom
3
of the hydraulic shovel relative to each other or the bucket angle representing the angles of the arm
4
and the bucket
5
relative to each other, an angle sensor that detects the angles of the booms and jibs of various cranes and an angle sensor that detects the angles of articulated arms of an articulated working apparatus.
Claims
- 1. A working apparatus for construction machine comprising:a first member; a second member rotatably linked with said first member via a linking member provided as an integrated part thereof; and an angle sensor having an input shaft driven to rotate by said first member and a sensor unit for detecting a rotating angle of said input shaft provided inside a case secured to said linking member, that detects a rotating angle of said first member relative to said second member, wherein; a recessed portion is formed at an end surface of said linking member along an axial direction thereof to house, at least, said case entirely within said recessed portion.
- 2. A working apparatus for construction machine comprising:a first member; a second member rotatably linked with said first member via a linking member provided as an integrated part thereof; an angle sensor internally provided with a sensor unit for detecting a rotating angle of an input shaft in a case secured to said linking member; and a communicating member that links said first member to said input shaft so as to drive said input shaft to rotate by interlocking with the rotation of said first member, wherein; (a) a recessed portion is formed at an end surface of said linking member along an axial direction thereof to house said case within said recessed portion; and (b) a projected portion projecting out along an axial direction of said input shaft is provided at an end surface of said case so as to enclose said input shaft outside a movement range of said communicating member.
- 3. A working apparatus according to claim 2, wherein;a distance over which said projected portion projects out from the end surface of said linking member along the axial direction thereof is set larger than the distance over which the end surface of said input shaft projects out from the end of the linking member along the axial direction of said input shaft.
- 4. A working apparatus according to claim 2, wherein;an input shaft protective cover that covers said input shaft for protection is provided, and said input shaft protective cover and said case are secured to said linking member with a common fastener.
- 5. A working apparatus according to claim 2, wherein;a passage for allowing a wiring harness extending from said sensor unit to be drawn out of said recessed portion is formed at said case.
- 6. A working apparatus according to claim 1, wherein;a seal member that seals an external circumferential surface of said case and an internal circumferential surface of said recessed portion is provided at said external circumferential surface; and a groove that allows a wiring harness extending from said sensor unit to be drawn out of said recessed portion is formed at said external circumferential surface and a passage for said wiring harness is formed at said seal member at a position aligned with said groove.
- 7. A working apparatus for construction machine comprising:a first member; a second member rotatably linked with said first member via a linking member provided as an integrated part thereof; an angle sensor having a sensor unit for detecting a rotating angle of an input shaft; and a communicating member that links said first member to said input shaft so as to drive said input shaft of said angle sensor to rotate by interlocking with rotation of said first member and a link between said first member and said input shaft is released when an external force equal to or exceeding a specific level is applied to said communicating member.
- 8. A working apparatus according to claim 7, wherein;one end of said communicating member is slidably inserted at a hole formed at said input shaft and another end thereof is secured to said first member, and the mechanical strength of said communicating member and the length over which said communicating member is inserted at said hole are set so as to allow a deformation resulting from an external force equal to or exceeding the specific level applied to said communicating member to cause said one end to slip out of said hole to release the link.
- 9. A working apparatus according to claim 7, wherein;the mechanical strength of said communicating member is set so as to cause said communicating member to become broken to release the link between said input shaft and said communicating member when an external force equal to or exceeding the specific level is applied to said communicating member.
- 10. A working apparatus according to claims 7, wherein;said angle sensor is provided with a case for housing said input shaft and said sensor unit; and a recessed portion is formed at an end surface of said linking member along an axial direction thereof to house, at least, the said case entirely within said recessed portion.
- 11. A working apparatus according to claims 7, wherein;said angle sensor is provided with a case for housing said input shaft and said sensor unit; (a) a recessed portion is formed at an end surface of said linking member along an axial direction thereof to provide said case in said recessed portion; and (b) a projected portion projecting out along an axial direction of said input shaft is provided at an end surface of said case so as to enclose said input shaft outside the movement range of said communicating member.
- 12. A working apparatus according to claims 1, wherein;said first member is an arm and said second member is a boom.
Priority Claims (3)
Number |
Date |
Country |
Kind |
11-088797 |
Mar 1999 |
JP |
|
11-088798 |
Mar 1999 |
JP |
|
11-113794 |
Apr 1999 |
JP |
|
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
5657544 |
Ota et al. |
Aug 1997 |
A |
Foreign Referenced Citations (5)
Number |
Date |
Country |
56-81504 |
May 1984 |
JP |
3-106406 |
Nov 1991 |
JP |
8-260525 |
Oct 1996 |
JP |
2000-170217 |
Jun 2000 |
JP |
2001-330022 |
Nov 2001 |
JP |
Continuations (1)
|
Number |
Date |
Country |
Parent |
PCT/JP00/01997 |
Mar 2000 |
US |
Child |
09/722566 |
|
US |