IE44503B1

IE44503B1 - Improvements in or relating to concrete mixers

Info

Publication number: IE44503B1
Application number: IE565/77A
Authority: IE
Original assignee: Hudelmaier Ingrid
Priority date: 1976-03-16
Filing date: 1977-03-15
Publication date: 1981-12-16
Also published as: IE44503L; DE2611054A1; JPS52128631A; BR7701586A; GB1533811A; ATA179777A; ZA771457B; FR2344389A1; DE2611054B2; AT346747B

Abstract

1533811 Concrete mixers I HUDELMAIER 4 March 1977 [16 March 1976] 09132/77 Heading B1C In a transport concrete mixer having a mixing drum I with elements 12 arranged on its inner surface for agitating concrete a supplementary mixing tool 19 is arranged coaxial in the drum and is rotatably drivable relative thereto characterised in that a controilable clutch 23 device is provided in the tool drive to permit disconnection of the drive to the mixing tool. In the embodiment described the drive to the drum incorporates drive to the tool and the clutch permits the disconnection of the tool from the drive to the drum. The drives are in the form of gears 13, 14 and 22, the tool 19 being driven in the opposite direction to the drum.

Description

This invention relates to a concrete mixing vehicle.

In one known form of concrete mixing vehicle, concrete is mixed in a rotatable mixing drum provided with fixed elements on its inner surface which agitate the concrete as the drum rotates, a mixing tool being also provided which projects into the drum coaxially thereof. The mixing tool is rotated by the same drive means as the mixing drum through a speed reducing gear drive. Therefore, the mixing tool and the drum always rotate simultaneously and it is not possible for the mixing tool to be either stationary or running freely, when the mixing drum is rotating.

In practice the mixing resistance in such concrete mixers occasionally rises so high that there is a danger that the drive means of the mixing drum drive will become jammed. This is because in certain mixing phases, the concrete is strongly compressed towards the end of the mixing drum having the mixing tool, by the mixing elements on the inner wall of the mixing drum and the mixing tool.

Furthermore, the energy requirement is unnecessarily high, because the mixing tool continues to operate during the filling and unloading processes, when supplementary mixing is not required. - 2 1 4 & ο 3 Jamming of the drive means can he prevented if tne concrete is able to flow away from the said end of the drum along a path in the area of the theoretical axis of the mixing drum.

According to the present invention there is provided a concrete mixing vehicle comprising a mixing drum which is rotatably mounted on the vehicle chassis and includes elements secured on its inner surface for agitating concrete held in the drum as the mixing drum rotates, a rotatable mixing tool projecting coaxially into the drum, and drive means for rotating the mixing drum and the mixing tool, the drive means including clutch means arranged so that the mixing tool can be disconnected from the drive means independently of the mixing drum.

A concrete mixing vehicle embodying the invention will now be particularly described, by way of example, with reference to the accompanying diagrammatic drawing in which: Figure 1 is a longitudinal section through the concrete mixing vehicle; and Figure 2 is a front view of a part of the concrete mixing vehicle of Fig. 1.

The illustrated concrete mixing vehicle comprises a mixing drum 1 which tapers conically toward both ends from an intermediate zone la_which has the greatest diameter. At the end of the rear tapering section lb is a filling and discharging opening 2, and at the end of the front tapering section l£ is a drum head 3. The mixing drum 1 is supported on a frame 4 which lies upon the chassis R of a transport vehicle F. The mixing drum 1 is arranged on the frame 4 so that its central longitudinal axis A is inclined upwards towards the filling and discharging opening 2. Surrounding the drum section lb. is a ring rail 5, which is supported on a pedestal 6 and acts as a rotatable support for the mixing drum 1. A further rotatable support is provided in the form of a hollow journal pin 7 which is connected to the drum head 3 and engages in a supporting base 8 seated on the frame 4. The supporting base 8 further carries a water tank 11.

AS03 Secured on the inner wall of the mixing -drum 1 are a series of inwardly extending blades 12 in a helical arrangement. They have a comparatively large pitch and are especially adapted for the conveyance of the concrete. When the mixing drum 1 rotates in one direction, the blades 12 draw the concrete, which has been loaded through the opening 2, toward the drum head 3, as indicated by an arrow P, when the mixing drum rotates in the opposite direction the concrete is conveyed out through the opening 2.

In order to rotate the mixing drum 1, an inner gear ring 13 is fastened to the exterior of the drum head 3 and engages with a pinion 14. The pinion 14 is mounted on a driven shaft 15 of a fluidmotor 16, carried by the supporting base 8. The fluid motor 16 is driven, via a pair of ducts 17, by a pump 18 which, in the illustrated embodiment, is driven by the motor of the vehicle F, but couTd, however, be driven by a separate drive motor.

In the mixing drum 1 there is provided a mixing tool 19 comprising three rings of blades 20 which are mounted on a shaft 21 and inclined with respect to one another at an angle of 120°. The star-shaped arrangement of the blades 20 and their arrangement on the shaft 21 is illustrated in detail in Fig. 2. The blades 20 of the middle ring are longer than the blades 20 of the two outer rings and so the former extends beyond the peripheries of the latter.

The shaft 21 projects into the interior of the mixing drum 1 from the drum head 3. It also extends outside the mixing drum 1 through the journal pin 7 and the supporting base 8. The shaft 21 is driven by the fluid motor 16 through the shaft 15 and a gear reduction drive 22 mounted laterally on the supporting base 8.

A clutch 23 is provided, controlled by a hand lever 24, whereby the shaft 21 can be engaged or disengaged from the gear reduction drive 22 and therefore from the fluid motor 16.

The mixing tool-19 is so dimensioned in the illustrated embodiment that it projects from the drum head 3 along the longitudinal axis of the mixing drum over abc-ut half the length of the mixing drum 1, but it could project for a somewhat shorter distance,'for example, a to j of the mixing drum length. - 4 .4503 The driven mixing tool 19 rotates in the opposite direction to the mixing drum 1, and the blades 20 are so arranged that they revolve closely within the inner edges of the helical blades 12. In this manner, positive mixing of the concrete in the mixing drum can be effected when the clutch 23 is engaged.

When the mixing tool 19 is required to rotate freely, the clutch 24 is disengaged. The mixing tool 19 is thereby disconnected from the driving action of the fluid motor 16, and can move independently of the mixing drum 1. This means that it can be completely stopped during filling and unloading of the mixing drum. Furthermore, it can be disengaged if a high mixing resitance occurs, so that the concrete which has been compressed in the neighbourhood of the drum head 3 can flow backwards in the direction opposite to that indicated by the arrow P, near the drum axis, freely rotating the mixing tool 19 as it passes.

In another embodiment of the invention a second fluid motor (also driven by the pump 18) may be provided for driving the mixing tool. In this case, instead of providing a mechanical clutch 23 in the zone of the gear reduction drive 22, a clutch dbvice would be provided in the connecting ducts between the pump 18 and the fluid motor of the mixing tool, to enable the pump output to the second fluid motor to be short circuited so that the second fluid motor could be stopped independently of the mixing drum.

From the foregoing it can been seen that by the introduction of a relatively simple structure into a concrete mixing vehicle, jamming of the mixing drum drive means can be prevented and energy usage can be reduced.

Claims

1. A concrete mixing vehicle comprising a mixing drum which is rotatably mounted oh the vehicle chassis and includes elements secured on its inner surface for agitating concrete held in the drum as the mixing drum rotates, a rotatable 5 mixing tool projecting coaxially into the drum, and drive means for rotating the mixing drum and the mixing tool, the drive means including clutch means arranged so that the mixing tool can be disconnected from the drive means independently of the mixing drum.

2. A concrete mixing vehicle according to Claim 1, wherein the drive means 10 comprises a pump arranged to drive a fluid motor whose output shaft is coupled both to the mixing drum and, via a gear reduction drive, to the mixing tool, the clutch means being arranged to engage or disengage the mixing tool from the gear reduction drive.

3. A concrete mixing vehicle according to Claim 1, wherein the drive means T5 comprises a pump arranged to drive two fluid motors, one of which serves to rotate the mixing drum and the other of which rotates the mixing tool,.the clutch means being arranged to engage or disengage the said, other fluid pump from the mixing tool.

4. - A concrete mixing vehicle, substantially as hereinbefore described with 20 reference to the accompanying drawing.