Reduction gear

Abstract

To provide a reduction gear which enables improvement of output torque.SOLUTION: A reduction gear 1 has a sun gear 21, a plurality of planetary gears 22, a carrier 23, a plurality of shafts 11, a sun gear transmission path 13, and a carrier transmission path 14. The plurality of planetary gears 22 is disposed around the sun gear 21 and meshes with the sun gear 21. The carrier 23 rotatably supports the plurality of planetary gears 22. A ring gear 24 is disposed around the plurality of planetary gears 22 and meshes with the plurality of planetary gears 22. The output of the electric motor 2 can be input to each of the plurality of shafts 11. The sun gear transmission path 13 transmits power input to the shaft 11 to the sun gear 21 to rotate the sun gear 21. The carrier transmission path 14 transmits the power input to the shaft 11 to the carrier 23 to rotate the carrier 23.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a speed reducer.

Background Art

[0002] Conventionally, a speed reducer provided with a planetary gear mechanism for traveling has been used in a working machine (see, for example, Patent Document 1). The planetary gear mechanism includes a sun gear, a plurality of planetary gears arranged around the sun gear, and a ring gear arranged around the plurality of planetary gears. The plurality of planetary gears are supported by a planetary carrier.

[0003] In the speed reducer shown in Patent Document 1, a hydraulic motor is used as a drive source, and traveling is performed by reducing the input from the hydraulic motor and outputting it.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when an electric motor is used as a drive source in a conventional speed reducer for speeding up, the output torque may be insufficient.

[0006] An object of the present disclosure is to provide a speed reducer capable of improving output torque.

Means for Solving the Problems

[0007] The speed reducer according to the first disclosure includes a sun gear, a plurality of planetary gears, a carrier, a plurality of input shafts, a sun gear transmission path, and a carrier transmission path. The plurality of planetary gears are arranged around the sun gear and mesh with the sun gear. The carrier rotatably supports the plurality of planetary gears. The ring gear is arranged around the plurality of planetary gears and meshes with the plurality of planetary gears. The plurality of input shafts are each capable of receiving the output of a motor. The sun gear transmission path transmits the power input to the input shaft to the sun gear to rotate the sun gear. The carrier transmission path transmits the power input to the input shaft to the carrier to rotate the carrier.

[0008] The speed reducer according to the second disclosure includes a sun gear, a plurality of planetary gears, a carrier, an input shaft, and a carrier transmission path. The plurality of planetary gears are arranged around the sun gear and mesh with the sun gear. The ring gear is arranged around the plurality of planetary gears and meshes with the plurality of planetary gears. The input shaft is capable of receiving the output of a motor, and the sun gear is fixed. The carrier transmission path transmits the power input to the input shaft to the carrier to rotate the carrier.

Advantages of the Invention

[0009] According to the present disclosure, it is possible to provide a speed reducer capable of improving the output torque.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 5

Figure 6

Figure 7

[0011] The speed reducer according to the embodiment of the present disclosure will be described below with reference to the drawings. The speed reducer of the present disclosure can be used, for example, in a working machine or a traveling device of a vehicle. Examples of the working machine include a bulldozer, a wheel loader, and an excavator. Further, the speed reducer of the present disclosure is not limited to the traveling device, and may be used in a transmission, or may be used in a swing machinery for swinging a revolving body when the working machine has a revolving body. Further, the speed reducer of the present disclosure may be used for swinging at a joint of a working machine of a working machine. Furthermore, the object to which the speed reducer of the present disclosure is applied is not limited to a working machine or a vehicle, and may be used, for example, in a robot or the like, and can be used in a configuration for reducing the power of an electric motor and outputting it.

[0012] (Embodiment 1) (Outline of Speed Reducer 1) FIG. 1 is a perspective view showing the overall configuration of the speed reducer 1 according to Embodiment 1 of the present disclosure. FIG. 2 is a perspective view showing the overall configuration of the speed reducer 1 as viewed from the side opposite to FIG. 1. FIG. 3 is an explanatory view of the gear train of the speed reducer 1 according to the first embodiment.

[0013] As shown in FIGS. 1 to 3, the speed reducer 1 of the present embodiment has a plurality of shafts 11, a planetary gear mechanism 12, a sun gear transmission path 13, and a carrier transmission path 14. As shown in FIG. 1, the plurality of shafts 11 are arranged parallel to each other. As shown in FIG. 3, the output of an electric motor 2 (an example of a motor) can be input to each shaft 11. The output shaft of the electric motor 2 can be connected to each shaft 11. As shown in FIG. 1, the speed reducer 1 of the present embodiment 1 has three shafts 11. In the explanatory diagram of the gear train in FIG. 3, only two shafts 11 are shown. In the present embodiment 1, the shaft 11 corresponds to an example of an input shaft.

[0014] As shown in FIG. 3, the driving force is transmitted from a sun gear shaft 43 (described later) to the planetary gear mechanism 12, and the driving force decelerated by the planetary gear mechanism 12 is output. Among the input shaft directions A along the shaft 11, the direction in which the output of the electric motor 2 is input to the shaft 11 is indicated by a first direction A1, and the direction opposite to the first direction A1 is indicated by a second direction A2. The planetary gear mechanism 12 is arranged on the first direction A1 side of the shaft 11.

[0015] As shown in FIG. 3, the sun gear transmission path 13 transmits the power input to the shaft 11 to the sun gear 21 of the planetary gear mechanism 12 to rotate the sun gear 21 (see the dotted line in FIG. 3). The carrier transmission path 14 transmits the power input to the shaft 11 to the carrier 23 of the planetary gear mechanism 12 to rotate the carrier 23 (see the dashed-dotted line in FIG. 3).

[0016] (Planetary Gear Mechanism 12) As shown in FIG. 2, the planetary gear mechanism 12 has a sun gear 21, a plurality of planetary gears 22, a carrier 23, and a ring gear 24. FIG. 4A is a view of the speed reducer 1 viewed from the first direction A1 side. FIG. 4B is a view of the speed reducer 1 viewed from the second direction A2 side. As shown in FIGS. 2 and 4A, the sun gear 21 is fixed to the sun gear shaft 43. The sun gear shaft 43 is arranged parallel to the shaft 11. In FIG. 3, the number of teeth of the sun gear 21 is indicated as Z1.

[0017] As shown in FIGS. 2 and 4A, a plurality of planetary gears 22 are arranged around the sun gear 21. Each planetary gear 22 meshes with the sun gear 21. When the sun gear 21 rotates, the planetary gears 22 rotate on their own axes. In the present embodiment, the planetary gear mechanism 12 has three planetary gears 22. In FIG. 3, the number of teeth of the planetary gear 22 is shown as Z2. Note that in the explanatory drawing of the gear train in FIG. 3, only two planetary gears 22 are shown.

[0018] The carrier 23 rotatably supports a plurality of planetary gears 22. FIG. 5 is a side view of the speed reducer 1 viewed along the direction of arrow B in FIG. 4A. FIG. 6 is a cross-sectional view taken along the line CC' in FIG. 4. As shown in FIGS. 5 and 6, the carrier 23 is arranged around the sun gear shaft 43 so as to be rotatable with respect to the sun gear shaft 43. The carrier 23 has a planetary gear support portion 31, a gear arrangement portion 32, and a connection portion 33.

[0019] The planetary gear support portion 31 is, for example, cylindrical as shown in FIG. 6. The planetary gear support portion 31 is arranged around the sun gear shaft 43 with the sun gear shaft 43 as the center. As shown in FIGS. 1 and 2, a plurality of through holes 31a are formed in the planetary gear support portion 31, and planetary gear shafts 34 for supporting the planetary gears 22 are arranged in the through holes 31a. The planetary gear shafts 34 are arranged along the input shaft direction A. The ends of the planetary gear shaft 34 on the first direction A1 side and the second direction A2 side are fixed to the edges of the through holes 31a of the planetary gear support portion 31. The planetary gears 22 are arranged inside the through holes 31a and are rotatably attached to the planetary gear shafts 34.

[0020] As shown in FIG. 6, the gear arrangement portion 32 is cylindrical. The gear arrangement portion 32 is arranged around the sun gear shaft 43 with the sun gear shaft 43 as the center. The gear arrangement portion 32 is arranged on the second direction A2 side of the planetary gear support portion 31. The gear arrangement portion 32 has a smaller diameter than the planetary gear support portion 31. A fourth driving gear 52, which will be described later, is fixed to the gear arrangement portion 32.

[0021] As shown in FIGS. 5 and 6, the connection portion 33 connects the planetary gear support portion 31 and the gear arrangement portion 32. The connection portion 33 is formed from the end on the second direction A2 side of the planetary gear support portion 31 toward the sun gear shaft 43 and is connected to the end on the first direction A1 side of the gear arrangement portion 32. When the carrier 23 configured as described above rotates, the plurality of planetary gears 22 revolve around the sun gear 21.

[0022] The ring gear 24 is arranged so as to surround the plurality of planetary gears 22. The ring gear 24 has teeth protruding inward and meshes with each planetary gear 22. As shown in FIG. 3, power is output from the ring gear 24. The rotation of the ring gear 24 becomes the output of the speed reducer 1.

[0023] (Sun Gear Transmission Path 13) As shown in FIG. 3, the sun gear transmission path 13 transmits the power input to the shaft 11 to rotationally drive the sun gear 21. The sun gear transmission path 13 includes a first driving gear 41, a second driving gear 42, and a sun gear shaft 43. The first driving gear 41 is fixed to each shaft 11. The first driving gear 41 rotates with the rotation of the shaft 11. Since the speed reducer 1 of the present embodiment is provided with three shafts 11 as shown in FIGS. 1 and 4B, three first driving gears 41 are provided. As shown in FIG. 4B, the shaft 11 and the first driving gear 41 are arranged on the same circumference centered on the sun gear shaft 43. The first driving gear 41 is arranged on the second direction A2 side of the planetary gear mechanism 12 as shown in FIG. 5. In FIG. 3, the number of teeth of the first driving gear 41 is shown as Z6. In the explanatory diagram of the gear train in FIG. 3, only two first driving gears 41 are shown.

[0024] The second driving gear 42 is arranged inside a plurality of first driving gears 41. The second driving gear 42 meshes with each first driving gear 41. The second driving gear 42 is fixed to the sun gear shaft 43. The second driving gear 42 is arranged on the second direction A2 side of the planetary gear mechanism 12. In FIG. 3, the number of teeth of the second driving gear 42 is shown as Z4.

[0025] The second driving gear 42 and the sun gear 21 are fixed to the sun gear shaft 43. The sun gear shaft 43 is arranged along the input shaft direction A. The sun gear shaft 43 is arranged at the center of a plurality of shafts 11.

[0026] In the first embodiment, the first driving gear 41 corresponds to an example of the first sun gear driving gear, and the second driving gear 42 corresponds to an example of the second sun gear driving gear.

[0027] (Carrier transmission path 14) The carrier transmission path 14 transmits the power input to the shaft 11 to rotationally drive the carrier 23.

[0028] As shown in FIG. 3, the carrier transmission path 14 includes a plurality of third driving gears 51 and a fourth driving gear 52. As shown in FIG. 5, the third driving gears 51 are fixed to the respective shafts 11. The plurality of third driving gears 51 are arranged on the first direction A1 side of the first driving gear 41. As shown in FIG. 4A, the plurality of third driving gears 51 are arranged on the same circumference centered on the sun gear shaft 43. The plurality of third driving gears 51 are arranged outside the gear arrangement portion 32 of the carrier 23 so as to surround the gear arrangement portion 32. In the speed reducer 1 of the first embodiment, as shown in FIGS. 2 and 4A, three third driving gears 51 are provided. In FIG. 3, the number of teeth of the third driving gear 51 is shown as Z7. In the explanatory diagram of the gear train in FIG. 3, only two third driving gears 51 are shown.

[0029] As shown in FIGS. 5 and 6, the fourth driving gear 52 is fixed to the gear arrangement portion 32 of the carrier 23. The fourth driving gear 52 is arranged on the outer periphery of the gear arrangement portion 32. The fourth driving gear 52 is arranged inside the plurality of third driving gears 51. The fourth driving gear 52 meshes with each of the third driving gears 51. In FIG. 3, the number of teeth of the fourth driving gear 52 is shown as Z5.

[0030] In the first embodiment, the third driving gear 51 corresponds to an example of the first carrier driving gear, and the fourth driving gear 52 corresponds to an example of the second carrier driving gear.

[0031] (Power transmission) The power transmission of the speed reducer 1 of the present embodiment will be described. Note that it is not necessary to input the power from the electric motor to all of the plurality of shafts 11, and the power from the electric motor may be input only to a part of them.

[0032] The transmission of power in the sun gear transmission path 13 will be described. As shown in FIG. 3, when the power of the electric motor 2 is input to the shaft 11 and the shaft 11 rotates, the first driving gear 41 rotates. Due to the rotation of the first driving gear 41, the second driving gear 42 meshing with the first driving gear 41 rotates, and the sun gear shaft 43 rotates. Due to the rotation of the sun gear shaft 43, the sun gear 21 fixed to the sun gear shaft 43 rotates. Due to the rotation of the sun gear 21, the planetary gear 22 rotates about the planetary gear shaft 34.

[0033] Next, the transmission of power in the carrier transmission path 14 will be described. When the power of the electric motor 2 is input to the shaft 11 and the shaft 11 rotates, the third driving gear 51 rotates. Due to the rotation of the third driving gear 51, the fourth driving gear 52 meshing with the third driving gear 51 rotates. Due to the rotation of the fourth driving gear 52, the carrier 23 rotates. Due to the rotation of the carrier 23, the plurality of planetary gears 22 revolve around the sun gear 21.

[0034] The difference between the rotation of the planetary gear 22 due to the sun gear transmission path 13 and the revolution of the planetary gear 22 due to the carrier transmission path 14 is transmitted to the ring gear 24, the ring gear 24 rotates, and the rotation of the ring gear 24 is output to the outside.

[0035] In the speed reducer 1 of the present embodiment, by adjusting the number of teeth Z6 of the first driving gear 41, the number of teeth Z4 of the second driving gear 42, the number of teeth Z1 of the sun gear 21, and the number of teeth Z2 of the planetary gear 22, the rotation of the planetary gear 22 can be controlled.

[0036] Also, in the speed reducer 1 of the present embodiment, by adjusting the number of teeth Z7 of the third driving gear 51 and the number of teeth Z5 of the fourth driving gear 52, the rotation of the carrier 23 can be controlled to control the revolution of the planetary gear 22.

[0037] Thus, in the speed reducer 1 of this embodiment, the rotation and revolution of the planetary gear 22 can be controlled independently.

[0038] (Reduction ratio) In the speed reducer 1 of this embodiment, the reduction ratio I between the input shaft and the output shaft can be expressed as I = {I1 × I2 × (I3 - 1)} / (I1 × I3 - I2), where I1 = Z4 / Z6, I2 = Z5 / Z7, and I3 = 1 + (Z3 / Z1). The reduction ratio is preferably set to 200 or more. As an example, when Z1 = 26, Z2 = 25, Z3 = 76, Z4 = 26, Z5 = 42, Z6 = 29, and Z7 = 12, the reduction ratio I can be 532.

[0039] (Features, etc.) As shown in FIG. 3, the speed reducer 1 of this embodiment includes a plurality of shafts 11 into which the output of the electric motor 2 can be input, a sun gear transmission path 13 that transmits the power input to the shaft 11 to the sun gear 21 to rotate the sun gear 21, and a carrier transmission path 14 that transmits the power input to the shaft 11 to the carrier 23 to rotate the carrier 23. Thus, since the output of the electric motor 2 can be input to each of the plurality of shafts 11, by increasing the number of electric motors 2, the torque input to the speed reducer 1 can be increased, and the output torque can be improved.

[0040] (Embodiment 2) Next, the speed reducer 101 of this embodiment 2 will be described. The speed reducer 101 of this embodiment 2 is different from the speed reducer 1 of Embodiment 1 in the shaft to which the power from the electric motor 2 is input. In the speed reducer 1 of Embodiment 1, the power from the electric motor 2 is input to the shaft 11, but in the speed reducer 101 of this embodiment 2, the power from the electric motor 2 is input to the sun gear shaft 43. In this embodiment 2, for the components having the same functions as those in Embodiment 1, the same reference numerals as those in Embodiment 1 are used, and the description thereof is omitted.

[0041] FIG. 7 is an explanatory diagram of the gear train of the speed reducer 101 according to Embodiment 2. The speed reducer 101 according to Embodiment 2 includes a planetary gear mechanism 12, a sun gear shaft 43, and a carrier transmission path 114. Power from the electric motor 2 is input to the sun gear shaft 43. Thereby, the sun gear shaft 43 rotates. Since the sun gear 21 is fixed to the sun gear shaft 43, it rotates together with the sun gear shaft 43. Due to the rotation of the sun gear 21, the planetary gear 22 rotates on its own axis. In Embodiment 2, the sun gear shaft 43 corresponds to an example of the input shaft (see the dotted line in FIG. 7).

[0042] The carrier transmission path 114 transmits the power input to the sun gear shaft 43 and rotationally drives the carrier 23 (see the dashed-dotted line in FIG. 7). The carrier transmission path 114 includes a second driving gear 42, a first driving gear 41, a shaft 11, a third driving gear 51, and a fourth driving gear 52.

[0043] When the sun gear shaft 43 rotates due to the output of the electric motor 2, the second driving gear 42 fixed to the sun gear shaft 43 also rotates. Due to the rotation of the second driving gear 42, a plurality of first driving gears 41 meshing with the second driving gear 42 rotate. Due to the rotation of the plurality of first driving gears 41, the shaft 11 to which each first driving gear 41 is fixed rotates, and the third driving gear 51 fixed to the shaft 11 also rotates. Due to the rotation of the plurality of third driving gears 51, the fourth driving gear 52 meshing with the plurality of third driving gears 51 rotates. Since the fourth driving gear 52 is fixed to the carrier 23, the carrier 23 rotates due to the rotation of the fourth driving gear 52. Due to the rotation of the carrier 23, the planetary gear 22 revolves around the sun gear 21. In Embodiment 2, the sun gear shaft 43 corresponds to an example of the input shaft, the second driving gear 42 corresponds to an example of the third carrier driving gear, the first driving gear 41 corresponds to the fourth carrier driving gear, the third driving gear 51 corresponds to an example of the fifth carrier driving gear, and the fourth driving gear 52 corresponds to an example of the sixth carrier driving gear.

[0044] In the speed reducer 101 of the present embodiment, by adjusting the number of teeth Z1 of the sun gear 21 and the number of teeth Z2 of the planetary gear 22, the rotation of the planetary gear 22 can be controlled.

[0045] Also, in the speed reducer 101 of the present embodiment, by adjusting the number of teeth Z4 of the second drive gear 42, the number of teeth Z6 of the first drive gear 41, the number of teeth Z7 of the third drive gear 51, and the number of teeth Z5 of the fourth drive gear 52, the rotation of the carrier 23 can be controlled to control the revolution of the planetary gear 22.

[0046] Thus, also in the speed reducer 101 of the present embodiment, similar to the speed reducer 1 of Embodiment 1, the rotation and revolution of the planetary gear 22 can be independently controlled.

[0047] In the speed reducer 101 of the present embodiment, the reduction ratio I between the input shaft and the output shaft can be expressed as I = {I2×(I3 - 1)} / (I1×I3 - I2), where I1 = Z4 / Z6, I2 = Z5 / Z7, and I3 = 1+(Z3 / Z1). When Z1 = 26, Z2 = 25, Z3 = 76, Z4 = 26, Z5 = 42, Z6 = 29, and Z7 = 12, the reduction ratio I = 593, and a higher reduction ratio can be obtained than in Embodiment 1, and the output torque can be improved.

[0048] (Features, etc.) The speed reducer 101 of the second embodiment can input the output of the electric motor 2, and includes a sun gear shaft 43 to which the sun gear 21 is fixed, and a carrier transmission path 114 that transmits the power input to the sun gear shaft 43 to the carrier 23 to rotate the carrier 23. By inputting the output of the electric motor 2 to the sun gear shaft 43, a high reduction ratio can be obtained, and the output torque can be improved. Also, the speed reducer 101 of the second embodiment can obtain a high output torque even if the input of the power from the electric motor 2 is at one location.

[0049] (Other embodiments) Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention. In particular, the plurality of embodiments and modifications described in this specification can be arbitrarily combined as needed.

[0050] (A) In the above Embodiments 1 and 2, as shown in FIGS. 3 and 7, the gears are arranged in three rows along the input shaft direction A, but it is not limited to three rows, and may be four rows or more.

[0051] (B) In the speed reducers 1 and 101 of the above Embodiments 1 and 2, three shafts 11 are provided, and three first driving gears 41 and three third driving gears 51 arranged on the shafts 11 are also provided, but it is not limited to three, and may be two or four or more.

[0052] (C) In the speed reducers 1 and 101 of the above Embodiments 1 and 2, three planetary gears 22 are provided, but it is not limited to three, and may be two or four or more. Also, the number of planetary gears 22 may be different from the number of shafts 11.

[0053] (D) In the above Embodiment 1, the shaft 11 is composed of one member as shown in FIG. 6, but it may be composed of a plurality of members connected together. In the above Embodiment 2, the sun gear shaft 43 is composed of one member as shown in FIG. 6, but it may be composed of a plurality of members connected together.

[0054] (E) In the above embodiment, an electric motor 2 is used as an example of the motor, but it is not limited thereto, and for example, a hydraulic motor may be used.

Industrial Applicability

[0055] The speed reducer of the present disclosure has the effect of being able to improve the output torque and is useful as a traveling device and a transmission of a working machine, etc.

Explanation of Signs

[0056] 1: Speed reducer 2: Electric motor (motor) 11: Shaft (input shaft) 12: Planetary gear mechanism 13: Sun gear transmission path 14: Carrier transmission path 21: Sun gear 22: Planetary gear 23: Carrier 24: Ring gear 31: Planetary gear support part 31a: Through hole 32: Gear arrangement part 33: Connection part 34: Planetary gear shaft 41: First driving gear (first sun gear driving gear, fourth carrier driving gear) 42: Second driving gear (second sun gear driving gear, third carrier driving gear) 43: Sun gear shaft (input shaft) 51: Third driving gear (first carrier driving gear, fifth carrier driving gear) 52: Fourth driving gear (second carrier driving gear, sixth carrier driving gear) 101: Speed reducer 114: Carrier transmission path

Claims

1. A sun gear, a plurality of planetary gears disposed around the sun gear and meshing with the sun gear, a carrier rotatably supporting the plurality of planetary gears, a ring gear disposed around the plurality of planetary gears and meshing with the plurality of planetary gears, a plurality of input shafts each capable of receiving the output of a motor, a sun gear transmission path for transmitting the power input to the input shaft to the sun gear to rotate the sun gear, a carrier transmission path for transmitting the power input to the input shaft to the carrier to rotate the carrier, a speed reducer.

2. A sun gear, a plurality of planetary gears disposed around the sun gear and meshing with the sun gear, a carrier rotatably supporting the plurality of planetary gears, a ring gear disposed around the plurality of planetary gears and meshing with the plurality of planetary gears, an input shaft capable of receiving the output of a motor and having the sun gear fixed thereto, a carrier transmission path for transmitting the power input to the input shaft to the carrier to rotate the carrier, a speed reducer.

3. The speed reducer according to claim 1 or 2, having a reduction ratio of 200 or more. The speed reducer according to claim 1 or 2.

4. The speed reducer according to claim 1 or 2, wherein power is output from the ring gear. The speed reducer according to claim 1 or 2.

5. The sun gear transmission path includes a first sun gear driving gear fixed to each of the plurality of input shafts, a second sun gear driving gear disposed inside the plurality of first sun gear driving gears, meshing with the plurality of first sun gear driving gears, and fixed to a sun gear shaft to which the sun gear is fixed. The carrier transmission path includes a first carrier driving gear fixed to each of the input shafts, a second carrier driving gear meshing with the plurality of first carrier driving gears and fixed to the carrier. The speed reducer according to claim 1.

6. The carrier transmission path includes a third carrier driving gear fixed to the input shaft, a plurality of fourth carrier driving gears disposed around the third carrier driving gear and meshing with the third carrier driving gear, a fifth carrier driving gear disposed coaxially with each of the plurality of fourth carrier driving gears and rotating together with the fourth carrier driving gear, a sixth carrier driving gear meshing with the plurality of fifth carrier driving gears and fixed to the carrier. The speed reducer according to claim 2.

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