JP6210825B2 - Power transmission device - Google Patents

Description

  When the inside of the casing tube inserted by rotation and push-in by the tubing device is excavated by the internal excavation device comprising the kelly bar and the excavation bucket, the force that causes the tubing device to rotate the casing tube is the kelly bar of the internal excavation device comprising the kelly bar and the excavation bucket. It is related with the power transmission device which transmits to a digging bucket via.

In the all casing method, when excavating the inside of the casing tube, or when creating a bottom-up pile at the lower part of the casing tube, internal excavation by an earth drill machine is performed.
In this case, if the excavation bucket is rotated through the kelly bar using the rotational force of the tubing device used in the all-casing method, a separate kelly drive for rotating the kelly bar is not required, thereby reducing costs. Can be realized.
Therefore, conventionally, a power transmission device has been conceived in which the casing tube and the kelly bar are directly connected, the casing tube is rotated by the hydraulic motor of the tubing device, and the rotational torque is directly transmitted to the kelly bar. For example, there is a tubing device shown in Patent Document 1 as an all-casing method.

JP2012-233392A

However, the method of directly connecting the casing tube and the kelly bar and directly transmitting the rotational torque of the tubing device to the kelly bar or the excavating bucket has the following problems.
The rated torque of the hydraulic motor of the tubing device is about 1000 to 2000 kN · m, while the rated torque of the hydraulic motor of the kelly drive that applies rotational torque to the kelly bar is about 100 kN · m. That is, generally speaking, the upper limit torque of the kelly bar or the excavating bucket is about 1/10 of the rated torque of the hydraulic motor of the tubing device.
Therefore, when the excavation bucket hits the bedrock while excavating with the kelly bar, there is a problem that an excessive torque higher than the upper limit torque acts on the kelly bar or the excavation bucket and the kelly bar or the excavation bucket is damaged.

  On the other hand, since the rated hydraulic pressure of the hydraulic motor of the tubing device is 30 MPa, it is conceivable to reduce the rotational torque transmitted to the Keriba by setting the hydraulic pressure used to about 3 MPa. However, a large rotational torque is required only by rotating the casing tube, and the rotational torque varies greatly due to the influence of mechanical loss and the like. Therefore, it is technically difficult to drive and control the Keriba by reducing the hydraulic pressure used to 3 MPa.

In order to solve the above problem, one of the present applicants proposed that a power transmission device be provided with a torque limiter mechanism according to Japanese Patent Application No. 2012-227926. That is, FIG. 15 shows the overall configuration of the power transmission device 900, and FIG. 13 shows the configuration of the torque limiter device of the power transmission device of the first reference example.
As shown in FIG. 15, a casing 902 is connected to the upper end of the casing tube 901 by a bolt 902a. Two protrusions 903 for transmitting torque are formed on the upper end surface of the casing 902.
On the other hand, as shown in FIG. 13, the kelly bar 906 is coupled to the torque limiter device 904 in the rotation direction by a kelly bar guide bar 907. Two extending portions 905 are formed on the outer periphery of the torque limiter device 904. The extending portion 905 engages with the convex portion 903 and transmits torque.
As shown in FIG. 13, the torque limiter device 904 includes an inner case 910 and an outer case 911. On the outer periphery of the inner case 910, triangular convex portions 912 are formed at eight locations. On the inner circumference of the outer case 911, concave portions are formed at eight locations, and a sliding member 909 having a triangular cross-section at the front end biased by the disc spring 908 is slidably held.

Next, the operation of the torque limiter device of the first reference example will be described.
When acting within the upper limit torque of the Kelly bar 906, the triangular convex portion 912 of the inner case 910 and the sliding member 909 of the outer case 911 are engaged. Therefore, the inner case 910 and the outer case 911 rotate integrally, and the rotational torque of the casing tube 901 is transmitted as it is to the kelly bar 906.
When an excessive torque exceeding the upper limit torque is applied to the kelly bar 906, the disc spring 908 is compressed and the sliding member 909 is retracted in the direction of the disc spring 908, so that the sliding member 909 and the triangular convex portion 912 The engagement state is released, and the sliding state is established, and the power transmission between the casing tube and the Kelly bar 906 is cut off. Therefore, an excessive rotational torque exceeding the upper limit torque of the Kelly bar 906 is not transmitted to the Kelly bar 906 any more.

Next, the configuration of the torque limiter device of the second reference example is shown in FIG. In the second reference example, the torque limiter device is incorporated in a casing 902 shown in FIG. Here, the kelly bar 906, the torque limiter device 904, and the extending portion 905 are integrally configured.
The upper end of the casing tube 901 extends outward, and an extended disc 901a is formed. The extended disc 901 a is sandwiched between a pair of brake pads 922 and 923 attached inside the casing 902. A predetermined pressing force is applied to the brake pad 922 by the hydraulic brake 921. Such hydraulic brakes are provided at a plurality of locations.
In the second reference example, the kelly bar 906 always rotates integrally with the extending portion 905.

Next, the operation of the torque limiter device of the second reference example will be described.
When operating within the upper limit torque of the Kelly bar 906, the brake pads 922 and 923 are engaged with the extended disk 901a, so that the casing 902 and the extended disk 901a are integrated with each other. The rotating torque of the casing tube 901 is transmitted to the Kelly bar 906 as it is.
When an excessive torque exceeding the upper limit torque is applied to the kelly bar 906, a slip occurs between the brake pads 922 and 923 and the extended disk 901a, and the power transmission between the casing tube and the kelly bar 906 is cut off. Therefore, an excessive rotational torque exceeding the upper limit torque of the Kelly bar 906 is not transmitted to the Kelly bar 906 any more.

Next, problems of the first and second reference examples will be described.
That is, the excavation bucket (not shown) attached to the tip of the Kelly bar 906 is rated for a plurality of allowable torques such as 100 kN · m, 75 kN · m, and 50 kN · m depending on the size. Therefore, every time the excavation bucket is replaced, the upper limit torque of the torque limiter device must be changed. In the first reference example, it is necessary to replace the eight disc springs 908, and there is a problem related to labor and time. Similarly, in the second reference example, it is necessary to replace a plurality of hydraulic brakes, and there is a problem of labor and time. Further, since the engagement is due to mechanical wear, wear at the frictional part is inevitable.

  The present invention has been made in order to solve the above-described problems, and when a drilling bucket to be used is changed, a power transmission device having a torque limiter device that can be easily adjusted to an allowable torque of the kelly bar or the drilling bucket. The purpose is to provide.

In order to achieve the above object, a power transmission device according to the present invention has the following configuration and functions.
(1) When the inside of a casing tube inserted by rotation and push-in by a tubing device is excavated by an internal excavation device comprising a kelly bar and a excavation bucket, the force that causes the tubing device to rotate the casing tube is And a power transmission device for transmitting to the excavation bucket, the torque limiter having a torque limiter for cutting off the power transmission between the casing tube and the kelly bar when the torque to be transmitted exceeds a preset upper limit torque. Has a hydraulic motor, and the upper limit torque is set by connecting an outlet port of the hydraulic motor to an inlet port via a relief valve.

  Thereby, since the torque is converted into the hydraulic pressure of the hydraulic motor and managed, the upper limit torque can be managed by the relief valve and the hydraulic pressure setting valve. Therefore, when the excavation bucket is changed, the upper limit torque of the torque limiter can be changed only by changing the connection between the relief valve and the hydraulic pressure setting valve, so that excavation bucket replacement can be easily handled. Therefore, the upper limit torque can be easily adjusted as compared with the torque limiters of the first reference example and the second reference example. In addition, since there is no mechanical friction engagement portion, it is not necessary to repair damage due to friction, so that maintenance costs can be reduced.

(2) In the power transmission device described in (1), the main body of the hydraulic motor is fixed to a torque limiter main body that engages with the casing tube, and an output shaft of the hydraulic motor is connected to a gear via a gear. It is connected to the Keriba, when the power is transmitted, the relief valve is closed, the output shaft of the hydraulic motor is fixed, and when the torque is over, the relief valve is open and the output of the hydraulic motor It is preferable that the shaft is in a free state.

(3) In the power transmission device described in (1) or (2), the power transmission device main body to which the main body of the hydraulic motor is attached has a plurality of extending portions, and the plurality of extending portions are It is preferable to engage with an uneven portion formed on the upper end surface of the casing tube, and a small gear attached to the output shaft of the hydraulic motor is engaged with a large gear connected to the Kelly bar.

  ADVANTAGE OF THE INVENTION According to this invention, when the excavation bucket to be used is changed, the power transmission device which has a torque limiter apparatus which can be easily adjusted to the allowable torque of the excavation bucket can be provided.

It is a front view of the power transmission device concerning a 1st embodiment. It is a side view of the power transmission device concerning a 1st embodiment. It is the partial cross section figure and circuit diagram (1) of the power transmission device which concern on 1st Embodiment. It is a side view of the state before the Keriba installation of the power transmission device which concerns on 1st Embodiment. It is a circuit diagram (2) of the power transmission device concerning a 2nd embodiment. It is a circuit diagram (3) of the power transmission device concerning a 3rd embodiment. It is a circuit diagram (4) of the power transmission device which concerns on 4th Embodiment. It is an excavation process figure (1) using the excavation apparatus concerning a 1st embodiment. It is an excavation process figure (2) using the excavation apparatus which concerns on 1st Embodiment. It is an excavation process figure (3) using the excavation apparatus which concerns on 1st Embodiment. It is a digging process figure (4) using the digging apparatus concerning a 1st embodiment. It is an excavation process figure (5) using the excavation apparatus which concerns on 1st Embodiment. It is sectional drawing of the power transmission device (1) which concerns on a 1st reference example. It is sectional drawing of the power transmission device (2) which concerns on a 2nd reference example. It is a perspective view of the tubing device concerning a reference example.

Hereinafter, embodiments of a power transmission device of the present invention will be described with reference to the drawings. FIG. 1 is a front view of the power transmission device according to the first embodiment. FIG. 2 shows a side view of the power transmission device. FIG. 3 shows a cross-sectional view and a circuit diagram (1) of the main part of the power transmission device. FIG. 4 is a side view showing a state of the power transmission device before the installation of the kelly bar.
(First embodiment)
<Overall configuration of power transmission device>
The power transmission device 2 is a device for transmitting the power of the tubing device 3 to be described later to the kelly bar 9 and the excavation bucket attached to the tip thereof.
As shown in FIG. 1, the power transmission device 2 has a double structure of a torque limiter main body 20 of an outer cylinder and a Keriba rotator 29 of an inner cylinder.

First, the torque limiter main body 20 will be described. The torque limiter main body 20 cuts power transmission between the casing tube 4 and the kelly bar 9 when the torque to be transmitted exceeds a preset upper limit torque. As shown in FIG. 1, the cylindrical torque limiter main body portion 20 is provided with four extending portions 21 toward the outer periphery in the radial direction. As shown in FIG. 4, an engaging portion 22 that engages with an engaging recess 45 that is fixed to the casing tube 4 described later is attached to the lower surface of the extending portion 21.
Further, the hydraulic motor 10, the torque adjusting unit 17, and the relief valve 121 are attached above the torque limiter main body 20 in FIG. 1. As shown in FIG. 3, an output shaft 11 is rotatably held by the hydraulic motor 10, and a small gear 12 is attached to the output shaft 11. The small gear 12 meshes with a large gear 28 formed on the outer periphery of a Keriba rotator 29 described later.
The hydraulic motor 10 uses an axial piston motor in this embodiment, but other hydraulic motors can also be used. The rated hydraulic pressure of the hydraulic motor 10 is 30 MPa.

Next, the Keriba rotator 29 will be described. As shown in FIG. 3, a cylindrical kelly bar through hole 23 is formed at the center of the kelly bar rotating body 29. In FIG. 3, the kelly bar 9 is omitted. Further, as shown in FIG. 1, six kerber recesses 24 are formed on the inner peripheral surface of the kerever through hole 23 to engage with the kerber 9 and transmit torque. A drill bucket 41 (FIG. 8) or a widened bucket 42 (FIG. 10) is attached to the tip of the kelly bar 9.
As shown in FIG. 3, a large gear 28 is attached to the outer peripheral disk portion 29 a of the Keriba rotator 29. A pair of bearings 30 are attached to the upper and lower positions of the outer peripheral disk portion 29 a, and the Keriba rotator 29 is held rotatably with respect to the torque limiter main body portion 20.
Further, an upper damper 25 is attached to the upper position of the Keriba rotator 29, and a lower damper 26 is attached to the lower position.

Next, the configuration of the hydraulic circuit will be described with reference to FIG.
As shown in FIG. 3, the hydraulic motor 10 has a first port 101, a second port 102, and a drain port 103.
For example, when the output shaft 11 rotates clockwise, the first port 101 serves as an inlet port and the second port 102 serves as an outlet port. When the output shaft 11 rotates counterclockwise, the first port 101 becomes an outlet port and the second port 102 becomes an inlet port.

The first port 101 and the second port 102 are connected by piping to form a hydraulic circuit 110.
The first pipe 151 communicating with the first port 101 communicates with the third pipe 153 via the first check valve 141. The third pipe 153 communicates with the second pipe 152 via the second check valve 142. The second pipe 152 communicates with the second port 102.
The first check valve 141 is a check valve that allows the flow from the first pipe 151 to flow and stops the reverse flow from the third pipe 153. The second check valve 142 is a check valve that flows the flow from the second pipe 152 and stops the reverse flow from the third pipe 153.

Further, the first pipe 151 communicates with the fourth pipe 154 through the third check valve 143. The fourth pipe 154 communicates with the second pipe 152 via the fourth check valve 144.
The third check valve 143 is a check valve that allows the flow from the fourth pipe 154 to flow and stops the reverse flow from the first pipe 151. The fourth check valve 144 is a check valve that allows the flow from the fourth pipe 154 to flow and stops the reverse flow from the second pipe 152.
A fifth pipe 155 communicates with the third pipe 153, and the fifth pipe 155 communicates with the sixth pipe 156 via the relief valve 121. The sixth pipe 156 and the fourth pipe 154 communicate with each other.

As shown in FIG. 3, the vent port 121 a of the relief valve 121 communicates with the pilot pipe 157. The vent port 121a is for changing the upper limit torque at which the relief valve 121 acts. As shown in FIGS. 1 and 3, the pilot pipe 157 can be arbitrarily connected to a first connection pipe 117, a second connection pipe 118, and a third connection pipe 119. In the present embodiment, the pilot pipe 157 is connected to the first connection pipe 117 as shown in FIG. The first connection pipe 117 is connected to a first hydraulic pressure setting valve 122 for setting the upper limit hydraulic pressure of the relief valve 121 to 20 MPa, and the second connection pipe 118 is a second pressure for setting the upper limit hydraulic pressure of the relief valve 121 to 15 MPa. The third connection pipe 119 is connected to a third hydraulic pressure setting valve 124 for setting the upper limit hydraulic pressure of the relief valve 121 to 10 MPa.
For example, when using a drill bucket 41 with an upper limit torque of 100 kN · m attached to the tip of the kelly bar 9, a set hydraulic pressure of 20 MPa, when the upper limit torque is 75 kN · m, a set hydraulic pressure of 15 MPa and an expanded bottom bucket with an upper limit torque of 50 kN · m By changing the connection destination of the pilot pipe 157 of the relief valve 121 so that the set hydraulic pressure becomes 10 MPa when using 42, the upper limit torque transmitted to the kelly bar 9 can be arbitrarily changed.

Therefore, when the excavation bucket attached to the tip of the kelly bar 9 is changed, only the connection destination of the relief valve 121 and the first hydraulic pressure setting valve 122, the second hydraulic pressure setting valve 123, and the third hydraulic pressure setting valve 124 is changed. Thus, the upper limit hydraulic pressure of the torque limiter can be changed, and the drill bucket 41 or the widened bucket 42 can be easily replaced.
Further, each of the first hydraulic pressure setting valve 122 connected to the first connection pipe 117, the second hydraulic pressure setting valve 123 connected to the second connection pipe 118, and the third hydraulic pressure setting valve 124 connected to the third connection pipe 119 at the construction site. By adjusting the set oil pressures to 20 MPa, 15 MPa, and 10 MPa corresponding to a plurality of Keriba used in the construction work process, it is possible to save the labor of adjustment at the site, so that the construction efficiency can be improved.
The first hydraulic pressure setting valve 122, the second hydraulic pressure setting valve 123, and the third hydraulic pressure setting valve 124 are all connected to a reserve pipe 114 that is connected to the reservoir tank 126.
As shown in FIG. 3, the drain port 103 is connected to a drain pipe 160 connected to the reservoir tank 126.

<Effect of drilling equipment>
Next, excavation work by the kelly bar 9 and excavation bucket using the power transmission device will be described with reference to FIGS.
A rotational force is transmitted from the casing tube 4 to the power transmission device 2.
In this embodiment, the tubing device 3 is fixed to the ground J in advance as shown in FIG. In this state, the casing tube 4 is excavated and pushed into the ground J by holding the outer periphery of the casing tube 4 with the holding member 35 and pushing down the casing tube 4 in the axial direction while rotating the casing tube 4. The casing tube 4 is set so that the engagement recess 45 comes to the uppermost part of the casing tube 4. The engagement recesses 45 are fixed at four positions on the diagonal line of the uppermost surface of the casing tube 4. Since the operation effect of the tubing device 3 is not different from that of the prior art, a detailed description is omitted. After the casing tube 4 is inserted, the power transmission device 2 is positioned above the casing tube 4 as shown in FIG.

Subsequently, as shown in FIG. 9, the engaging recess 45 attached to the upper end of the casing tube 4 is engaged with the engaging portion 22 of the power transmission device 2. Thereby, the motive power of the casing tube 4 can be transmitted to the kelly bar 9.
The power transmission device 2 rotates the kelly bar 9 and excavates the earth and sand in the casing tube 4 with the drill bucket 41 at the tip thereof. The excavation is finished when the soil is excavated to the target.
As shown in FIG. 10, the power transmission device 2 is lifted to the ground, and the drill bucket 41 attached to the tip of the kelly bar 9 is replaced with the expanded bottom bucket 42.
As shown in FIG. 11, the engagement recess 45 provided at the upper end of the casing tube 4 is engaged with the engagement portion 22 of the power transmission device 2. Thereby, the motive power of the casing tube 4 can be transmitted to the kelly bar 9.
Next, as shown in FIG. 12, the power transmission device 2 rotates the kelly bar 9 to expand the diameter of the bottom-expanded bucket 42 at the tip thereof, thereby expanding the bottom. Thereby, an expanded bottom pile can be created.
The excavation work is thus completed.

<Effect of power transmission device>
-Normal use state In this embodiment, the 1st port 101 shown in Drawing 3 is an exit port, and the 2nd port 102 is an entrance port.
Under normal conditions, the oil flowing out to the first port 101 increases the pressure in the third pipe 153 via the first pipe 151 and the first check valve 141. The oil that is about to flow out to the third pipe 153 does not flow out to the second pipe 152 by the second check valve 142.

Normally, when drilling the earth and sand with the drill bucket 41, it rotates within the upper limit torque. Therefore, excessive torque exceeding the upper limit torque of 100 kN · m of the drill bucket 41 attached to the tip of the kelly bar 9 is small. The output shaft 11 is not applied via the gear 12. The output shaft 11 receives the rotational torque of the kelly bar 9 via the large gear 28 and the small gear 12. However, excessive torque exceeding the upper limit torque of 100 kN · m for the normal rotation of the kelly bar 9 is not applied to the output shaft 11. Therefore, since the oil tends to flow out to the third pipe 153, the pressure in the third pipe 153 increases. However, in normal times, the pressure in the third pipe 153 does not exceed the upper limit hydraulic pressure of 20 MPa. Therefore, the relief valve 121 which does not operate unless the upper limit hydraulic pressure is 20 MPa or more does not operate.
Since the relief valve 121 does not operate, the first port 101 and the second port 102 are not in communication and the output shaft 11 does not rotate. Therefore, the output shaft 11 always rotates integrally with the large gear 28.

  From the above, in the normal state, when the casing tube 4 rotates, the torque limiter main body portion 20 engaged through the engaging portion 22 rotates. Since the output shaft 11 and the large gear 28 are integrally rotated, the kelly bar rotating body 29 that engages with the torque limiter main body 20 rotates in the same manner, and the kelly bar 9 fixed in the kelly bar rotating body 29 rotates. .

・ Usage condition where excessive torque exceeding the upper limit torque is applied to the Keriba For example, the rated torque of the hydraulic motor 10 of the tubing device 3 is about 1000 to 2000 kN · m, while the rated torque of the hydraulic motor 10 that gives rotational torque to the Keriba 9 The torque is about 100 kN · m. That is, the upper limit torque of the kelly bar 9 and the excavating bucket attached to the tip thereof is generally about 1/10 of the rated torque of the tubing device 3.
Therefore, when the excavation bucket hits the bedrock while excavating with the kelly bar 9 and the excavation bucket, excessive torque exceeding the upper limit torque acts on the kelly bar 9 and the excavation bucket, and the kelly bar 9 or the excavation bucket may be damaged. There is sex.
In the present embodiment, the hydraulic motor 10 cuts off the power transmission between the casing tube 4 and the kelly bar 9 when the torque transmitted by the excavation bucket hitting the rock mass exceeds a preset upper limit torque. Therefore, an excessive torque equal to or higher than the upper limit torque does not act on the kelly bar 9 and the kelly bar 9 or the excavation bucket is not damaged.

Specifically, oil that is about to flow out to the first port 101 flows out to the third pipe 153 via the first pipe 151 and the first check valve 141. The oil that has flowed out to the third pipe 153 does not flow out to the second pipe 152 by the second check valve 142.
When an excessive torque exceeding the upper limit torque is applied to the kelly bar 9, the excessive torque is received by the output shaft 11 via the small gear 12. Therefore, an excessive torque is applied to the output shaft 11 to increase the pressure of the oil flowing out into the third pipe 153 and exceed the upper limit hydraulic pressure of 20 MPa. Accordingly, the pressure in the third pipe 153 increases beyond the upper limit hydraulic pressure of 20 MPa, the relief valve 121 is activated, and the valve is opened.

When the relief valve 121 is opened, the third pipe 153 and the sixth pipe 156 communicate with each other. The oil that flows out to the sixth pipe 156 flows out to the second pipe 152 via the fourth pipe 154 and the fourth check valve 144 and then flows out to the second port 102. That is, the first port 101 and the second port 102 are communicated.
When the first port 101 and the second port 102 communicate with each other, the output shaft 11 rotates, and the output shaft 11 and the large gear 28 are released from the integrated state and become free.

Further, for example, in the present embodiment, the drill bucket 41 has an upper limit torque of 100 kN · m, and the widened bucket 42 has an upper limit torque of 50 kN · m. The reason is that, compared with the drill bucket 41 that excavates in the downward direction, the diameter of the bottom expansion bucket 42 is increased, and thus the shape is complicated. For this reason, the bottom expansion bucket 42 is more complicated, so the failure frequency is high and the upper limit torque needs to be reduced.
For example, as shown in FIG. 8, when using the drill bucket 41, the pilot pipe 157 is connected to the first connection pipe 117 in order to set the upper limit hydraulic pressure to 20 MPa. On the other hand, as shown in FIGS. 11 and 12, when the bottomed bucket 42 is used, the pilot pipe 157 is connected to the third connection pipe 119 in order to set the upper limit hydraulic pressure to 10 MPa. In the present embodiment, the upper limit torque can be easily changed by changing the connection destination of the pilot pipe 157 of the relief valve 121.

When the pilot pipe 157 is connected to the third connection pipe 119, the pilot pipe 157 is connected to the third hydraulic pressure setting valve 124, and the upper limit hydraulic pressure becomes 10 MPa.
When an excessive torque exceeding the upper limit torque is applied to the kelly bar 9, the excessive torque is received by the output shaft 11 via the small gear 12. Therefore, an excessive torque is applied to the output shaft 11 to increase the pressure of the oil flowing out into the third pipe 153 and exceed the upper limit hydraulic pressure of 10 MPa. Therefore, the pressure in the third pipe 153 increases beyond the upper limit oil pressure of 10 MPa, the relief valve 121 is activated, and the valve is opened.

When the relief valve 121 is opened, the third pipe 153 and the sixth pipe 156 communicate with each other. The oil that flows out to the sixth pipe 156 flows out to the second pipe 152 via the fourth pipe 154 and the fourth check valve 144 and then flows out to the second port 102. That is, the first port 101 and the second port 102 are communicated.
When the first port 101 and the second port 102 communicate with each other, the output shaft 11 rotates, and the output shaft 11 and the large gear 28 are released from the integrated state and become free.

  From the above, when an excessive torque exceeding the upper limit torque of the excavation bucket attached to the tip of the kelly bar 9 is applied to the kelly bar 9, when the casing tube 4 rotates, the torque limiter is engaged via the engaging portion 22. The main body 20 rotates. Since the integration of the output shaft 11 and the large gear 28 is released, the Keriba rotating body 29 engaged with the torque limiter main body 20 rotates separately, and an excessive torque is applied to the Keriva 9 fixed in the Keriba rotating body 29. Will not take. Therefore, the Keriba 9 or the excavation bucket is not damaged.

  In the present embodiment, there is a hydraulic motor 10 that cuts off the power transmission between the casing tube 4 and the kelly bar 9 when the torque to be transmitted exceeds a preset upper hydraulic pressure of 20 MPa. Further, the first port 101 that is the outlet port of the hydraulic motor 10 is connected to the second port 102 that is the inlet port via the relief valve 121. Therefore, it is possible to prevent the excessive torque from being transmitted to the kelly bar 9 only by adjusting the hydraulic pressure of the relief valve 121.

As described above in detail, the power transmission device according to the present invention has the following configurations and operational effects.
(1) When the inside of the casing tube 4 inserted by rotation and push-in by the tubing device 3 is excavated by the internal excavation device comprising the kelly bar 9 and the excavation bucket, the force that causes the tubing device 3 to rotate the casing tube 4 is And a power transmission device 2 for transmitting to the kelly bar 9 of the internal excavator comprising the excavation bucket. Moreover, the torque limiter main body 20 for cutting off the power transmission between the casing tube 4 and the kelly bar 9 when the torque to be transmitted exceeds a preset upper limit torque. Further, the torque limiter body 20 has the hydraulic motor 10, and the upper limit torque is set by connecting the outlet port of the hydraulic motor 10 to the inlet port via the relief valve 121.
Accordingly, since the torque is managed by converting into the hydraulic pressure of the hydraulic motor 10, for example, when the drill bucket 41 is used, the relief valve 121 and the first hydraulic pressure setting valve 122 are connected, and when the bottom expansion bucket 42 is used, the relief valve is connected. The torque can be managed by connecting the valve 121 and the third hydraulic pressure setting valve 124. Therefore, when the drill bucket 41 and the bottom expansion bucket 42 are changed, the torque limiter main body can be simply changed by changing the connection between the relief valve 121 and the first hydraulic pressure setting valve 122, the second hydraulic pressure setting valve 123, and the third hydraulic pressure setting valve 124. Since the upper limit torque of the portion 20 can be changed, the drill bucket 41 and the widened bucket 42 can be easily replaced.

Furthermore, in the power transmission device 2 described in (1), the main body of the hydraulic motor 10 is connected to the casing tube 4, and the output shaft 11 of the hydraulic motor 10 is connected to the kelly bar 9 via the small gear 12. . When the power is transmitted, the relief valve 121 is closed and the output shaft 11 of the hydraulic motor 10 is fixed. When the torque is over, the relief valve 121 is open and the output shaft 11 of the hydraulic motor 10 is free. State.
Thereby, the torque can be converted into the hydraulic pressure of the hydraulic motor 10 and managed.

  Further, since there is no mechanical friction engagement portion, it is not necessary to repair against wear due to friction, so that maintenance costs can be reduced.

(Second Embodiment)
The second embodiment is different from the first embodiment only in the configuration of the hydraulic circuit, and the rest of the configuration is the same as that of the first embodiment.
FIG. 5 shows the hydraulic circuit 210. 5 that are similar to those of the hydraulic circuit 110 according to the first embodiment shown in FIG.
As shown in FIG. 5, the relief valve 121 communicates with the pilot pipe 157. The pilot pipe 157 communicates with the connection pipe 213 and the first connection pipe 117 via the first manual valve 211. The connection pipe 213 communicates with the second connection pipe 118 and the third connection pipe 119 via the second manual valve 212.

In the present embodiment, the pilot pipe 157 is connected to the first connection pipe 117 via the first manual valve 211 since the first manual valve 211 is in the ON state as shown in FIG. The connection pipe 117 is connected to the first hydraulic pressure setting valve 122 having an upper limit hydraulic pressure of 20 MPa. The pilot pipe 157 communicates with the second connection pipe 118 via the first connection pipe 213 and the second manual valve 212. The second connection pipe 118 is connected to the second hydraulic pressure setting valve 123 having an upper limit hydraulic pressure of 15 MPa. It is connected. The pilot pipe 157 is connected to the third connection pipe 119 via the connection pipe 213 and the second manual valve 212. The third connection pipe 119 is connected to the third hydraulic pressure setting valve 124 having an upper limit hydraulic pressure of 10 MPa. ing.
The relief valve 121 changes the connection destination to the first hydraulic pressure setting valve 122, the second hydraulic pressure setting valve 123, and the third hydraulic pressure setting valve 124 by switching ON / OFF of the first manual valve 211 and the second manual valve 212. The upper limit torque can be adjusted.

<Effect of power transmission device>
-Use state in which excessive torque exceeding upper limit torque is applied to Keriba The operational effect of the power transmission device of the second embodiment is the same as that of the power transmission device of the first embodiment. Only different operational effects will be described below.
For example, in the present embodiment, the upper limit torque differs between the drill bucket 41 and the bottom expanded bucket 42. The reason is that, compared with the drill bucket 41 that excavates in the downward direction, the diameter of the bottom expansion bucket 42 is increased, and thus the shape is complicated. Therefore, since the bottom expansion bucket 42 has a higher failure frequency, the upper limit torque needs to be small.
For example, as shown in FIG. 9, when the drill bucket 41 is used, the first manual valve 211 is turned on in order to set the upper limit hydraulic pressure to 20 MPa. On the other hand, as shown in FIGS. 11 and 12, when using the bottomed bucket 42, the first manual valve 211 is turned off and the second manual valve 212 is turned off in order to set the upper limit hydraulic pressure to 10 MPa. . In the present embodiment, the connection destination of the relief valve 121 can be changed by adjusting ON / OFF of the first manual valve 211 and the second manual valve 212, and the upper limit torque can be adjusted. Therefore, since the upper limit torque can be adjusted without changing the connection of the pilot pipe 157 as compared with the first embodiment, the workability is good.

Specifically, as shown in FIG. 5, when the first manual valve 211 is in the ON state, the pilot pipe 157 communicates with the first connection pipe 117 via the first manual valve 211. Further, since the first hydraulic pressure setting valve 122 communicates, the relief valve 121 is opened when the rated hydraulic pressure becomes 20 MPa or more.
When the first manual valve 211 is in the OFF state and the second manual valve 212 is in the ON state, the pilot pipe 157 passes through the first manual valve 211, the first connection pipe 213, and the second manual valve 212. The second connection pipe 118 communicates. Further, since the second hydraulic pressure setting valve 123 communicates, the relief valve 121 is opened when the rated hydraulic pressure becomes 15 MPa or more.
When the first manual valve 211 is in the OFF state and the second manual valve 212 is in the OFF state, the pilot pipe 157 passes through the first manual valve 211, the first connection pipe 213, and the second manual valve 212. The third connection pipe 119 communicates. Further, since the third hydraulic pressure setting valve 124 is communicated, the relief valve 121 is opened when the rated hydraulic pressure becomes 10 MPa or more.
In addition, it is not necessary to reconnect the pipes simply by operating the first manual valve 211 and the second manual valve 212, so that construction efficiency can be further improved.

  In the present embodiment, the use of the relief valve can be selected by turning on / off the first manual valve 211 and the second manual valve 212.

(Third embodiment)
The third embodiment is different from the first embodiment only in the configuration of the hydraulic circuit, and the rest of the configuration is the same as that of the first embodiment. Therefore, the hydraulic circuit having a different configuration will be described.
FIG. 6 shows the hydraulic circuit 310. 6 that are the same as those of the hydraulic circuit 110 according to the first embodiment shown in FIG.
As shown in FIG. 6, the first port 101 and the second port 102 are connected by piping to form a hydraulic circuit 310. The hydraulic circuit 310 has no connection piping connected to the relief valve 121 as compared to the hydraulic circuit 110 in the first embodiment shown in FIG. This is the minimum configuration when it is not necessary to easily change the upper limit torque.
Therefore, since no hydraulic setting valve other than the relief valve 121 is required, the equipment cost can be reduced. In addition, the set hydraulic pressure can be changed by changing the spring attached to the relief valve 121.
The effect of the power transmission device is the same as that of the first embodiment except that the upper limit torque cannot be easily changed by changing the connection piping.

(Fourth embodiment)
The fourth embodiment is different from the first embodiment only in the configuration of the hydraulic circuit, and the rest of the configuration is the same as that of the first embodiment. Therefore, the hydraulic circuit having a different configuration will be described.
FIG. 7 shows the hydraulic circuit 410. 7 that are similar to those of the hydraulic circuit 110 according to the first embodiment shown in FIG.
The first pipe 151 communicating with the first port 101 communicates with the third pipe 153C via the first check valve 141C. The third pipe 153C communicates with the second pipe 152 via a relief valve 155C. Further, the third pipe 153C communicates with the sixth pipe 156C. The second pipe 152 communicates with the second port 102.
The first check valve 141C is a check valve that stops backflow from the first pipe 151 and flows from the second pipe 152C.

Further, the first pipe 151 communicates with the fourth pipe 154C via a relief valve 159C. The fourth pipe 154C communicates with the second pipe 152 via the fourth check valve 144C. The fourth pipe 154C communicates with the sixth pipe 156C.
The third check valve 143C is a check valve that allows the flow from the first pipe 151 to flow and stops the reverse flow from the sixth pipe 156C. The second check valve 142C is a check valve that stops the backflow from the second pipe 152 and flows the flow from the fourth pipe 154C. The sixth pipe 156C also communicates with the reservoir tank 126.

<Effect of power transmission device>
A usage state in which excessive torque exceeding the upper limit torque is applied to the kelly bar For example, when excessive torque is applied to the kelly bar 9 in the clockwise direction, the excessive torque is received by the output shaft 11 via the small gear 12. Therefore, an excessive torque is applied to the output shaft 11 in the direction corresponding to the clockwise rotation of the kelly bar 9, so that the pressure of the oil flowing into the first pipe 151 is increased. Therefore, the pressure in the first pipe 151C increases to exceed 20 MPa, the relief valve 159C is activated, and the valve is opened.

When the relief valve 159C is opened, the first pipe 151 and the fourth pipe 154C communicate with each other. The oil from the fourth pipe 154C goes to the second pipe 152 via the fourth check valve 144C and flows out to the second port 102. Thereby, the first port 101 and the second port 102 are communicated.
When the first port 101 and the second port 102 communicate with each other, the output shaft 11 rotates, and the output shaft 11 and the large gear 28 are not integrated.

  From the above, when the excessive torque acts on the kelly bar 9 in the clockwise direction, when the casing tube 4 rotates, the torque limiter main body portion 20 engaged through the engaging portion 22 rotates. Since the integration of the output shaft 11 and the large gear 28 is released, the kerber rotator 29 that engages with the torque limiter main body 20 rotates separately, and the keliva 9 fixed in the kerrier rotator 29 rotates clockwise. No excessive torque is applied. Therefore, the Keriba 9 is not damaged.

  In the present embodiment, the relief valve used differs depending on whether the hydraulic motor 10 rotates to the right or to the left. Therefore, when the torque is different between the right rotation and the left rotation, it is effective because the torque can be changed. For example, when the rock is excavated by the kelly bar 9 when rotating clockwise, the work does not proceed if the torque setting is low. On the contrary, the torque setting may be high because there is no risk of damage to the kelly bar 9 during the left rotation. Thus, it is effective when the torque differs between right rotation and left rotation.

<Modification>
Note that the present invention is not limited to the above-described embodiment, and various applications are possible without departing from the spirit of the invention.
For example, in the present embodiment, three hydraulic pressure setting valves having different set hydraulic pressures are installed, but four or more hydraulic pressure setting valves can be installed. By installing four or more, the upper limit torque can be changed to four or more. Further, when there are two hydraulic pressure setting valves, the hydraulic pressure setting can be changed.
For example, in this embodiment, the engaging portion 22 that engages with the engaging recess 45 fixed to the casing tube 4 is attached to the lower surface of the extending portion 21. It is also possible to provide an engagement concave portion on the lower surface and provide an engagement convex portion on the casing tube 4.

DESCRIPTION OF SYMBOLS 1 Excavator 2 Power transmission device 3 Tubing device 4 Casing tube 9 Keriba 10 Hydraulic motor 20 Torque limiter main-body part 121 Relief valve

Claims (2)

When the inside of the casing tube inserted by rotation and push-in by the tubing device is excavated by an internal excavation device comprising a kelly bar and a excavation bucket, the force that causes the tubing device to rotate the casing tube is transmitted to the kelly bar of the internal excavation device. In the power transmission device to
Having a torque limiter that cuts off power transmission between the casing tube and the Keriba when the torque to be transmitted exceeds a preset upper limit torque;
The torque limiter has a hydraulic motor;
Setting the upper limit torque by connecting an outlet port of the hydraulic motor with an inlet port via a relief valve;
The main body of the hydraulic motor is fixed to a torque limiter main body that engages with the casing tube, and the output shaft of the hydraulic motor is connected to the Keriba via a gear;
When power is transmitted, the relief valve is closed and the output shaft of the hydraulic motor is fixed. When torque is over, the relief valve is open and the output shaft of the hydraulic motor is free. ,
A power transmission device characterized by. When the inside of the casing tube inserted by rotation and push-in by the tubing device is excavated by an internal excavation device comprising a kelly bar and a excavation bucket, the force that causes the tubing device to rotate the casing tube is transmitted to the kelly bar of the internal excavation device. In the power transmission device to
Having a torque limiter that cuts off power transmission between the casing tube and the Keriba when the torque to be transmitted exceeds a preset upper limit torque;
The torque limiter has a hydraulic motor;
Setting the upper limit torque by connecting an outlet port of the hydraulic motor with an inlet port via a relief valve;
A power transmission device main body to which the main body of the hydraulic motor is attached has a plurality of extending portions, and the plurality of extending portions engage with an uneven portion formed on an upper end surface of the casing tube;
A small gear attached to an output shaft of the hydraulic motor is engaged with a large gear connected to the Keriba;
A power transmission device characterized by.

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