AU2012390023A1

AU2012390023A1 - Mixer drum device

Info

Publication number: AU2012390023A1
Application number: AU2012390023A
Authority: AU
Inventors: Tetsuo KASAHARA; Yosuke Ota
Original assignee: Kayaba Industry Co Ltd
Current assignee: KYB Corp
Priority date: 2012-09-12
Filing date: 2012-09-12
Publication date: 2015-04-09
Anticipated expiration: 2032-09-12
Also published as: WO2014041644A1; AU2012390023B2; CN104619471A; NZ705831A; JP5933726B2; JPWO2014041644A1

Abstract

A mixer drum device for a mixer car, for stirring a stored material, provided with a drum arranged so as to be able to rotate on a vehicle body and formed so that one end thereof is an open end and the other end is a closed end, a drum blade arranged in a helical shape along an inner wall surface of the drum, and a sub blade extending from a distal end part of the drum blade toward the center of rotation of the drum. The sub blade is provided toward the open end of the drum.

Description

'J _ k 1'J I 1r 7 / % I (3u1"J't F _%,III%,C 1% DESCRIPTION TITLE OF INVENTION MIXER DRUM DEVICE TECHNICAL FIELD [0001] The present invention relates to a mixer drum device of a concrete mixer truck to agitate a storage object. BACKGROUND ART [0002] A concrete mixer truck is a vehicle to transport ready-mixed concrete (storage object) loaded in a drum rotatably disposed on a vehicle body. [0003] Japanese Unexamined Patent Application Publication No. 2006-298031 discloses a concrete mixer truck including a mixer drum device formed by a drum rotatably disposed on a vehicle body and mixing blades spirally disposed along an inner wall surface of the drum. SUMMARY OF INVENTION [0004] With such a concrete mixer truck, the ready-mixed concrete may overflow the mixing blade located at the rearmost of the drum and spill out from an opening end of the drum, when, for example, a vehicle starts to move forward or a moving vehicle makes a stop. The spillover of the ready-mixed concrete has been prevented conventionally by reducing a load capacity of the ready-mixed concrete or increasing the size of the drum. The reduction in the load capacity of the ready-mixed concrete or the increase in the size of the drum for the purpose of preventing leakage of the ready-mixed concrete causes an increase in transportation costs and drum manufacturing costs. 1 [0005] The present invention is made in view of the above-described problems, and it is an object of the present invention to provide a mixer drum device of a concrete mixer truck capable of preventing an increase in costs and preventing spillover of a storage object from a drum when, for example, a vehicle starts to move forward. [0006] According to one aspect of the present invention, a mixer drum device for a mixer truck to agitate a storage object is provided. The mixer drum device includes a drum rotatably disposed on a vehicle body and configured to have an opening end on one end side and a closure end on another end side, a mixing blade disposed spirally along an inner wall surface of the drum, and a sub-blade extended from an edge portion of the mixing blade toward a center of rotation of the drum. The sub-blade is provided near the opening end of the drum. [0007] The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS [0008] Fig 1 is a side view of a concrete mixer truck including a mixer drum device according to an embodiment of the present invention. Fig. 2 is a view showing a mixing blade viewed from the front side in an axial direction of the drum. Fig. 3 is a vertical sectional view of the mixing blade located near an opening end of the drum. Fig. 4 is a view explaining a distance between the center of rotation of the drum and an edge of a sub-blade at predetermined angle intervals in a circumferential direction of the drum. 2 Fig. 5A is a partial cross-sectional view of the mixer drum device according to this embodiment. Fig. 5B is a partial cross-sectional view of a mixer drum device according to a comparative example. Fig. 6 is a partial cross-sectional view of a mixer drum device according to a modification example of this embodiment. DESCRIPTION OF EMBODIMENT [0009] A concrete mixer truck 1 including a mixer drum device 10 according to an embodiment of the present invention will be explained with reference to Fig. 1 to Fig. 5A. [0010] As shown in Fig. 1, the concrete mixer truck 1 has the mixer drum device 10 to agitate ready-mixed concrete, on a vehicle body 2. [0011] The mixer drum device 10 includes a drum 20 that is rotatably disposed on the vehicle body 2, a pair of mixing blades 30 that are disposed spirally along an inner wall surface 21 of the drum 20, and a not-shown drum driving unit that allows the drum 20 to rotate based on engine power. [0012] The drum 20 is formed by a cylindrical portion 20A that is at the center in an axial direction, a front conical portion 20B that reduces its diameter from the cylindrical portion 20A toward the front of the vehicle, and a rear conical portion 20C that reduces its diameter from the cylindrical portion 20A toward the rear of the vehicle. The drum 20 has a bottomed cylindrical shape capable of receiving the ready-mixed concrete as a storage object. The front end of the drum 20 is formed as a closure end 22 closing the drum 20, and the rear end of the drum 20 is formed as an opening end 23 opening the drum 20. The ready-mixed concrete is charged and discharged through the opening end 23 of the drum 20. 3 [0013] The drum 20 is supported by supports 2A, 2B provided at the front and the rear of the vehicle body 2, so as to rotate about a rotation center line C. The drum 20 is arranged on the vehicle body 2 while it is leaning forward with the opening end 23 side being lifted upward. Therefore, the rotation center line C of the drum 20 declines toward the front of the vehicle. [0014] A hopper 3 for charging the ready-mixed concrete into the drum 20 is provided at an upper rear part of the opening end 23 of the drum 20. The ready-mixed concrete charged to the hopper 3 is introduced from the opening end 23 of the drum 20 into the drum 20. [0015] Further, a scoop 4 and a chute 5 for guiding the discharged ready-mixed concrete are provided at a lower rear part of the opening end 23 of the drum 20. The ready-mixed concrete discharged from the opening end 23 of the drum 20 is guided by the scoop 4 to the chute 5, and discharged by the chute 5 to a desired location. [0016] The mixing blades 30 are disposed spirally along the inner wall surface 21 of the drum 20. The pair of the mixing blades 30 are provided in the drum 20, and the mixing blades 30 are located to have a phase difference of 1800 with respect to a rotation center line C. [0017] When charging and agitating the ready-mixed concrete, the drum 20 is driven to rotate in a counterclockwise direction viewed from the rear of the vehicle. When the drum 20 is rotated normally like this, the ready-mixed concrete in the drum 20 is sent from the rear to the front of the drum 20 by the mixing blades 30 rotating with the drum 20. This allows the ready-mixed concrete to be charged and agitated. [0018] Meanwhile, when discharging the ready-mixed concrete, the drum 20 is driven to rotate in a clockwise direction viewed from the rear of the vehicle. When the drum 20 is rotated reversely like this, the ready-mixed concrete in the drum 20 is sent from the front to the 4 rear of the drum 20 by the mixing blades 30 rotating with the drum 20. This allows the ready-mixed concrete to be discharged from the opening end 23 of the drum 20. [0019] Next, the structure of each of the mixing blades 30 in the mixer drum device 10 will be explained with reference to Fig. 2 to Fig. 4. [0020] As shown in Fig. 2, the mixing blade 30 is formed as one spiral member by connecting a plurality of fan-shaped blade plates in a circumferential direction. [0021] As shown in Fig. 2 and Fig. 3, the mixing blade 30 is formed by an edge portion 30A on the center of rotation side of the drum 20, a base portion 30B on the inner wall surface 21 side of the drum 20, and a center portion 30C between the edge portion 30A and the base portion 30B. The base portion 30B of the mixing blade 30 is welded to the inner wall surface 21 of the drum 20 so that the mixing blade 30 is fixed to the drum 20. [0022] The center portion 30C of the mixing blade 30 is formed flatly, and the edge portion 30A and the base portion 30B are formed to curve from the center portion 30C toward the opening end 23 side of the drum 20. In other words, the mixing blade 30 is formed to have a bowl-shaped cross-sectional shape in a direction perpendicular to the rotation center line C. The bowl-shaped cross-sectional shape of the mixing blade 30 allows the ready-mixed concrete to slide smoothly on the mixing blade 30 at the time of discharging the ready-mixed concrete, so that discharging efficiency of the ready-mixed concrete can be improved. The discharging efficiency is excellent not only when the vehicle is on a flat ground, but also when the vehicle is inclined toward the front, such as when the vehicle is on a slope. [0023] The mixing blade 30 is provided spirally along the longitudinal direction of the drum 20, and a sub-blade 40 is integrally 5 formed at the edge portion 30A of the mixing blade 30 that is located near the opening end 23 of the drum 20, that is, at the rear of the drum 20. The sub-blade 40 extends from the edge portion 30A of the mixing blade 30 toward the center of rotation of the drum 20. This sub-blade 40 is a member to function as a dam wall that prevents the ready-mixed concrete from overflowing the mixing blade 30 located at the rearmost of the drum 20 when, for example, the vehicle starts to move forward. Incidentally, a corner portion 31 as a coupling portion between the sub-blade 40 and the mixing blade 30 is formed to curve with a predetermined curvature. [0024] As shown in Fig. 2, the sub-blade 40 is formed spirally along the edge portion 30A of the mixing blade 30. The sub-blade 40 is formed to make at least one turn in the drum 20, and is structured so that a front end portion 41 and a rear end portion 42 of the sub-blade 40 in the longitudinal direction of the drum overlap one another. When structured as above, it is possible for the sub-blade 40 to dam up a flow of the ready-mixed concrete that tends to overflow the mixing blade 30, regardless of a rotational position of the drum 20. [0025] As shown in Fig. 3, the sub-blade 40 is formed standingly from the edge portion 30A of the mixing blade 30 toward the center of rotation of the drum 20. From the viewpoint of efficiently damming up the ready-mixed concrete, it is desirable that an angle 0, which is between an extension line of the sub-blade 40 in an extension direction (broken line in Fig. 3) and the rotation center line C of the drum 20, facing the closure end 22 of the drum 20, is equal to or larger than 90' and smaller than 1800. [0026] However, when the sub-blade 40 is inclined too much toward the closure end 22 side of the drum 20, it is likely that the ready-mixed concrete adheres to and stays at the corner portion 31 formed between the edge portion 30A of the mixing blade 30 and the 6 sub-blade 40, and that chipping operation is difficult to perform at the time of cleaning the inside of the drum 20. Considering the above, it is further desirable that the angle 0, which is between the extension line of the sub-blade 40 in the extension direction and the rotation center line C of the drum 20, facing the closure end 22 of the drum 20, is equal to or larger than 900, and is equal to or smaller than 1350. [0027] Fig. 4 is a view showing the mixing blade 30 and the sub-blade 40, aligned from the opening end 23 side of the drum 20, at predetermined angle intervals (about 220) in the circumferential direction of the drum. [0028] As shown in Fig. 4, the sub-blade 40 in a region R1, from a position on the opening end 23 side of the drum 20 to a predetermined position on the closure end 22 side, is configured to have a constant distance between the tip of the sub-blade 40 and the rotation center line C of the drum 20. When the interval between the tip of the sub-blade 40 and the center of rotation is made constant at the position near the opening end 23, it is possible to prevent the ready-mixed concrete from overflowing the mixing blade 30 in the vicinity of the opening end 23 more securely. [0029] The sub-blade 40 in a region R2, on the closure end 22 side than the predetermined position, is formed to increase the distance between the tip of the sub-blade 40 and the rotation center line C of the drum 20 as it approaches the closure end 22 side. When a projection amount of the sub-blade 40 is gradually reduced toward the closure end 22 like this, it is possible to prevent the flow of the ready-mixed concrete from being interrupted by the sub-blade 40, at the time of charging the ready-mixed concrete, for example. [0030] It should be noted that, when the predetermined position as a boundary between the region RI and the region R2 is set more inward in the drum 20 (closure end side), it is possible to increase a 7 limit load capacity of the ready-mixed concrete in the drum 20. The limit load capacity defines a limit capacity with which the ready-mixed concrete does not overflow the rearmost mixing blade 30 to spill out from the drum 20 while the vehicle is making a stop and performing agitation and rotation. It is preferable that the predetermined position as the boundary between the region RI and the region R2 is located at the position that is equal to or larger than 1500 in the circumferential direction of the blade from the opening end 23 of the drum 20 along the mixing blade 30. [0031] Next, the behavior of the ready-mixed concrete when the vehicle starts to move forward with a predetermined capacity of the ready-mixed concrete loaded thereon will be explained with reference to Fig. 5A and Fig. 5B. Fig. 5A is a view showing the concrete mixer truck 1 having the mixer drum device 10 according to this embodiment, and Fig. 5B is a view showing a concrete mixer truck 201 having a mixer drum device 210 as a comparative example. [0032] As shown in Fig. 5B, the concrete mixer truck 201 as the comparative example includes a bowl-shaped mixing blade 230 in a drum 220, but does not include a sub-blade formed at the tip of the mixing blade 230. Therefore, when the stopping concrete mixer truck 201 starts to move forward, a part of the ready-mixed concrete in the drum 220 may overflow the mixing blade 230 at the rearmost of the drum 220, as shown by arrows A2 in Fig. 5B, and spill out from an opening end 223 of the drum 220. [0033] Meanwhile, as shown in Fig. 5A, when the concrete mixer truck 1 according to this embodiment starts to move forward, the ready-mixed concrete is dammed up by the sub-blade 40 formed at the mixing blade 30 near the opening end 23 of the drum 20, as shown by an arrow Al in Fig. 5A, so that the ready-mixed concrete does not overflow the sub-blade 40. 8 [0034] The following effects can be obtained by the mixer drum device 10 of the concrete mixer truck 1 according to the above-described embodiment. [0035] In the mixer drum device 10 of the concrete mixer truck 1, the sub-blade 40 that is standingly provided from the edge portion 30A of the mixing blade 30 toward the center of rotation side of the drum is formed at the mixing blade 30 near the opening end 23 of the drum 20, so that the flow of the ready-mixed concrete toward the opening end 23 side can be dammed up, and the ready-mixed concrete can be prevented from spilling out of the drum 20, when, for example, the concrete mixer truck 1 starts to move forward. Further, it is not necessary to reduce a load capacity of the ready-mixed concrete or to increase the size of the drum 20 in order to prevent the ready-mixed concrete from spilling out of the drum, and therefore, loading efficiency of the ready-mixed concrete in the drum 20 is not reduced. [0036] When the sub-blade 40 is provided like this, it is possible to increase the load capacity of the ready-mixed concrete and to improve the loading efficiency of the ready-mixed concrete, even when the drum 20 having the same size as that of the conventional drum is used. [0037] The embodiment of the present invention has been explained thus far, but the above-described embodiment is only one of the application examples of the present invention, and does not intend to limit the technical scope of the present invention to the concrete structure of the above-described embodiment. [0038] According to this embodiment, the sub-blade 40 is integrally formed at the edge portion 30A of the mixing blade 30, but this is not restrictive. For example, the mixing blade 30 and the sub-blade 40 may be formed as separate members, and the sub-blade 40 may be fixed to the edge portion 30A of the mixing blade 30 by 9 welding and the like. [0039] Further, although the mixing blade 30 is configured to have the bowl-shaped cross-sectional shape according to this embodiment, it may be configured to have an I-shaped cross-sectional shape as shown in Fig. 6. By forming the sub-blade 40 at the mixing blade 30 near the opening end 23 of the drum 20, it is also possible for a concrete mixer truck 101 according to a modification example shown in Fig. 6 to prevent the ready-mixed concrete from spilling out from the opening end 23 of the drum 20 when, for example, the vehicle starts to move forward. However, when the vehicle is inclined toward the front, the discharging efficiency of the ready-mixed concrete is extremely poor in the case where the mixing blade 30 having the I-shaped cross-sectional shape is used, as compared with the case where the mixing blade 30 having the bowl-shaped cross-sectional shape is used. The mixing blade 30 having the I-shaped cross-sectional shape may be used, but it is desirable to use the mixing blade 30 having the bowl-shaped cross-sectional shape in order to improve the discharging efficiency. 10

Claims

1. A mixer drum device for a mixer truck to agitate a storage object, comprising: a drum rotatably disposed on a vehicle body and configured to have an opening end on one end side and a closure end on another end side; a mixing blade disposed spirally along an inner wall surface of the drum; and a sub-blade extended from an edge portion of the mixing blade toward a center of rotation of the drum, wherein the sub-blade is provided near the opening end of the drum.

2. The mixer drum device as defined in claim 1, wherein the sub-blade is configured to make at least one turn along the edge portion of the mixing blade.

3. The mixer drum device as defined in claim 1 or claim 2, wherein the sub-blade is configured that an angle, which is in face of the closure end between an extension line of the sub-blade in an extension direction and a rotation center line of the drum, is equal to or larger than 900 and is equal to or smaller than 1350.

4. The mixer drum device as defined in any one of claim 1 to claim 3, wherein the sub-blade from the opening end to a predetermined position on a closure end side is configured to have a constant distance between a tip of the sub-blade and the center of rotation of the drum.

5. The mixer drum device as defined in claim 4, wherein the 11 sub-blade located on the closure end side from the predetermined position is configured to increase a distance between the tip of the sub-blade and the center of rotation of the drum as the sub-blade approaches the closure end.

6. The mixer drum device as defined in claim 4, wherein the predetermined position is set at a position equal to or larger than 1500 in a circumferential direction of the mixing blade from the opening end along the mixing blade.

7. The mixer drum device as defined in any one of claim 1 to claim 6, wherein the mixing blade and the sub-blade are integrally formed.

8. The mixer drum device as defined in any one of claim 1 to claim 7, wherein the mixing blade comprises the edge portion on the side of center of drum rotation, a base portion on the side of an inner wall surface of the drum, and a center portion which is located between the edge portion and the base portion, and the edge portion and the base portion are formed to curve from the center portion toward the opening end side. 12