GB2152898A

GB2152898A - Waste collection apparatus

Info

Publication number: GB2152898A
Application number: GB08401305A
Authority: GB
Inventors: Michael John Howard
Original assignee: MACKRILL ENGINEERING Ltd D
Current assignee: MACKRILL ENGINEERING Ltd D
Priority date: 1984-01-18
Filing date: 1984-01-18
Publication date: 1985-08-14
Also published as: GB2152898B; GB8401305D0

Abstract

Waste collection apparatus is primarily for refuse vehicles and seeks to provide more even packing of the vehicle. The apparatus includes a container body into which waste is packed by packing means 8,9 at one end of the body. The body contains a reciprocal blade 4 controlled by a hydraulic multi-stage cylinder.The packing means includes hydraulic operating cylinders 6,7 and by controlling the movement of the blade 4 according to the pressure in the operating cylinders 6,7 an even packing of the waste in the body 2 is achieved. <IMAGE>

Description

SPECIFICATION Waste collection apparatus This invention relates to refuse collection apparatus equipped with means for collecting, compress ing and carrying waste for subsequent ejection and disposal.

Hitherto a vehicle chassis has been equipped with a large collection body inside which is an ejector blade capable of travelling to and fro along the full length of the body under the action of a multistage telescopic hydraulic cylinder. At an opening to the rear of the body is fitted a tailgate capable of receiving the waste and fitted internally with a pair of hinged blades powered by hydraulic cylinders; the blades operating in a controlled sequence to gather in and compress the waste into the body. At the commencement of the loading operation the ejector blade is positioned towards the rear of the body adjacent the tailgate and, as the waste is pushed into the body by the packing blades, it is compressed against the rear face of the ejector blade and the roof of the main body.As more waste is forced into the body the load on the ejector blade increases, the pressure in the ejector blade hydraulic cylinder rises and acts on the valve of a relief valve built into the hydraulic circuit.

When the pressure reaches a predetermined level the relief valve opens and oil is vented from the ejector blade hydraulic cylinder back to the hydraulic system oil reservoir, and the ejector blade moves forwards.

Conventionally the collection bodies are long, and in order to obtain the maximum usable volume and to achieve correct axle loading of the vehicle, the ejector blade must travel right up to the front of the body. Consequently the ejector blade hydraulic cylinder has a long extended length and a short retracted length necessitating the use of a multistage telescopic cylinder, in some cases having up to 5 or 6 stages. Since each stage must close inside the next stage the cylinder diameter of the first stage is much bigger than the diameter of the last stage, and the thrust produced by the cylinder varies by a large ratio over the total stroke of the cylinder against a fixed relief valve, the thrust being a minimum at full extension and a maximum just before full retraction.

When the initial loading commences the ejector blade hydraulic cylinder produces only a comparatively low reaction force to the waste compaction and the ejector blade moves forwards comparatively easily, and the initial loads are not very densely compacted. As the ejector blade moves further and further up the body the reaction force becomes higher and higher and the later loads are more densely compacted. This results in various disadvantages. Less waste is compacted into the body during the early loading operation than during the later stages, and the weight distribution of the waste in the body is biased towards the rear, leading to overloading of the vehicle rear axle.

An object of the invention is to provide improved waste collection apparatus in which a collection body is more evenly loaded with waste material.

According to the invention waste collection apparatus includes a container body, a blade movable reciprocally along the body to accommodate and eject waste material in the body, hydraulicallyoperated actuating means for resisting movement of the blade along the body during loading of the body and for driving the blade along the body during ejection of the waste material from the body, packing means for packing waste material into one end of the body against the blade, hydraulicallyoperated drive means for operating the packing means, control means for controlling movement of the blade during loading of the body by sensing the resistance to operation of the packing means and providing a signal to actuate movement of the blade during loading independently of the pressure in the actuating means for the blade whereby the control means enables the blade to move when pressure in the packing means reaches a predetermined level.

In this way the compaction pressure in the waste material is maintained substantially constant throughout a packing operation and the load in the body is more evenly distributed.

Further features of the invention appear from the following description of an embodiment of the invention given by way of example only and with reference to the drawings, in which: Figure 1 is a schematic side elevation of a commercial vehicle, Figures 2a, 2b, 2c and 2d are side elevations of the vehicle of Figure 1 showing a packing sequence, and Figure 3 is a circuit diagram showing the hydraulic circuit for the control of the apparatus.

Referring to Figure 1, a commercial vehicle chassis 1 is fitted with a container body 2. Inside the body 2 is an ejector blade 4, the blade having slides (not shown) engaging with longitudinal rails in the body 2 so that it is slidable from one end of the body to the other. Pivotally mounted from an upper rear crossmember of the body is a tailgate 3, shown in full lines in a lowered position for loading the body and in chain dotted lines, position 3', for load discharge. Connected between the lower rear edge of the ejector blade 4 and an upper front crossmember 10 of the collection body 2, is a multistage telescopic double acting hydraulic cylinder 5, arranged such that extension of the cylinder moves the ejector blade 4 towards the rear of the body and retraction of the cylinder moves the ejector blade towards the front of the body.

Referring now to Figures 2a, 2b, 2c and 2d these show in greater detail the tailgate 3 of Figure 1. In Figures 2a and 2b a guide blade 9 is shown in an upper position. The blade 9 is mounted on rollers (not shown) running in channel guideways and can move from the upper position of Figures 2a and 2b to a lower position shown in Figures 2c and 2d.

Movement of the blade 9 is controlled by hydraulic cylinders, represented by dotted lines 6, pivotally mounted on the guide blade 9 by a pin 12 and on the tailgate 3 by a pin 13, the cylinders 6 being extended when the blade 9 is in an upper position and retracted when the blade is in a lower position. Pivoted to the lower end of the guide blade 9 is a swivel blade 8 driven by hydraulic cylinders represented by dotted lines 7. The cylinders 7 are pivotally connected to the swivel blade 8 by a pin 11 and to the guide blade 9 by a pin 12. Extension of the cylinders 7 closes the swivel blade in relation to the guide blade to the positions shown in Figures 2a and 2d and retraction of the cylinders opens the swivel blade to the positions shown in Figures 2b and 2c.

At the start of a loading cycle the blades 4, 8 and 9 are in the position shown in Figure 2a and waste is loaded into a lower curved receiving trough 14 of the tailgate 3. The swivel blade 8 is then opened and moved from the position of Figures 2a to that of Figure 2b by retraction of the hydraulic cylinders 7. The guide blade 9 then moves from the position of Figure 2b to that of Figure 2c under the retraction of hydraulic cylinders 6. When the guide blade 9 reaches its lower position of Figure 2c the swivel blade 8 closes from position of Figure 2c to that of Figure 2d under extension of hydraulic cylinders 7 to 'gather in' the waste. The guide blade 9 now moves from its lower position of Figure 2d to its upper position of Figure 2a under extension of the hydraulic cylinders 6 taking up with it the swivel blade 8.This upward motion of the blades 8 and 9 carries the waste up into the body 2 compressing the waste against the rear face of the ejector blade 4 and against the roof of the body.

The amount of force required to compress the waste depends on the spare space available between the blades 8 and 9, together called packing blades, and the ejector blade 4, and on the stiffness of the waste. The smaller the space available and the stiffer the waste the more force, and hence hydraulic pressure to the full bore side of hydraulic cylinders 6 is required.

As this pressure increases so the point of stall is progressively approached and for the cycle and subsequent loading to continue then the ejector blade 4 must be moved forwards to provide more space. To allow the ejector blade to move forwards, oil must be released from the ejector blade hydraulic ram 5.

Reference should now be made to Figure 3 showing a hydraulic circuit open loop servo control system for the ejector blade back pressure.

Shown on Figure 3 is one of the hydraulic cylinders 6 giving the movement to the guide blade 9.

Extension of these cylinders causes the guide blade 9, together with the swivel blade 8 to move upwards, thus compacting the waste. Under extension of the cylinder hydraulic oil is fed to the cylinder 6 through pipe 15 and from pipe 15 a connection is taken to a sequence valve 16. This valve is set at a predetermined pressure and, when the required packing force gives rise to this pressure, the sequence valve opens and permits oil to flow to a pressure regulator valve 17. This valve reduces the value of the input signal to a constant output pressure and this output is fed to an auto shuttle valve 18. In the feed line from the regulator valve 17 to the shuttle valve 18 a T-junction piece is fitted providing a flow path via a fixed orifice 22 back to a hydraulic system oil reservoir 24.This orifice 22 is fitted to ensure a continuous flow through the regulator thus providing output pressure stability and also the orifice provides a vent to eliminate any possible hydraulic lock at changeover of the auto shuttle valve 18. From the auto shuttle valve 18 which at this condition would be in the opposite mode from that shown, a signal is provided to the pilot of a pilot-operated load control valve 19. The load control valve is connected to the full bore of the ejector blade multistage telescopic hydraulic cylinder 5. Incorporated in the load control valve 19 is an additional internal pilot signal sensing the pressure in the ejector cylinder and a reverse-flow check valve 19'.

Under loading operation as the packing pressure rises the pressure in the ejector cylinder 5 rises but is held by the load control valve 19, since the internal pilot pressure is insufficient to move the spool over against the spring, and thus compaction of the waste occurs. Eventually the packing pressure reaches a sufficient value to open the sequence valve 16, flow is initiated to the pressure regulator 17, an output is obtained from the regulator 17 and, via the auto shuttle valve 18, an external pilot signal is provided to the load control valve 19.The sum of this pressure on its acting area plus the internal pilot pressure on its acting area provide a sufficient force to overcome the spring of the load control valve 19 and the spool opens to permit oil to flow out of the ejector cylinder 5, through the load control valve 19 and via pipe 25 to a service port A of a three position directional control valve 21 and then through the valve 21 and back to the oil reservoir 24. As the oil flows out of the ejector cylinder 5 the ejector blade 4 moves forwards, the pressure in the cylinder 5 falls, the load control valve internal pilot pressure decays and the valve 19 moves towards a closed position thus progressively restoring the ejector cylinder back pressure.

Thus with this control system a continuous sensing exists, monitoring the packing system pressure and progressively controlling the ejector cylinder back pressure and the ejector blade position and resistive force to give a matched uniform packing of the waste regardless of ejector cylinder stage diameter or ejector blade position.

Several other components are included in the circuit to provide full operation. As the ejector cylinder 5 progressively closes oil is exhausted from the full bore side and oil is sucked into the annulus side of the cylinder from the oil reservoir 24 via the lightly spring loaded check valve 23, thus avoiding cavitation in the annulus.

A relief valve 20 is fitted to a T junction in the line connecting the ejector cylinder 5 to the load control valve 19 to provide a maximum limit to the ejector cylinder back pressure and a maximum limit to the feed pressure to the ejector cylinder.

The three position directional control valve 21, which is manually operated, provides fore and aft movement of the ejector blade 4. To extend the ejector cylinder 5 the valve spool of valve 21 is moved to the left, pressure feed is then available from port A and travels via pipe 25, the free flow check valve 19' in the load control valve 19 and thence to the ejector cylinder full bore, thus extending the cylinder 5. Oil from the cylinder annulus returns to the oil reservoir 24 via a port B in the control valve 21. To retract the ejector cylinder 5 the spool is moved to the right and pressure is then available at port B and is fed to the annulus of the ejector cylinder. To enable the full bore of the cylinder 6 to exhaust to the oil reservoir 24 it is necessary to open the load control valve 19. To achieve this, a signal line is taken from port B via the auto shuttle valve 18 to the pilot of the load control valve 19, the signal pressure being sufficient to open the load control valve completely and thus provide a free flow from the cylinder full bore via pipe 25, into port A of the control valve 21 and back to the oil reservoir 24.

Claims

1. Waste collection apparatus includes a container body, a blade movable reciprocally along the body to accommodate and eject waste material in the body, hydraulically-operated actuating means for resisting movement of the blade along the body during loading of the body and for deiving the blade along the body during ejection of the waste material from the body, packing means for packing waste material into one end of the body against the blade, hydraulically-operated drive means for operating the packing means, control means for controlling movement of the blade during loading of the body by sensing the resistance to operation of the packing means and providing a signal to actuate movement of the blade during loading independently of the pressure in the actuating means for the blade whereby the control means enables the blade to move when pressure in the packing means reaches a predetermined level.

2. Apparatus according to Claim 1 wherein the hydraulically-operated actuating means for the blade includes a multi-stage double-acting hydraulic cylinder.

3. Apparatus according to Claim 1 or 2 wherein the packing means includes a reciprocable guide blade and a pivotable blade, operable in synchronism by the hydraulically-operated drive means.

4. Apparatus according to Claim 1, 2 or 3 wherein the control means includes valve means which senses when a predetermined pressure level is reached in the packing means and operates a relief valve for the blade actuating means.

5. Apparatus according to Claim 4 wherein the valve means includes a sequence valve which is operated when said predetermined pressure level is reached and causes operation of a load control or relief valve controlling discharge of pressure from the blade actuating means.

6. Apparatus according to Claim 5 including a pressure regulating valve regulating the pressure from the sequence valve and feeding a shuttle valve connected to the load control valve.

7. Apparatus according to any one of the preceding claims wherein the control means includes a load control valve connected to the hydraulicallyoperated actuating means for the blade, the load control valve being actuated by sensing the pressure in the hydraulically-operated drive means for the packing means and the pressure in the hydraulically-operated actuating means for the blade.

7. Waste collection apparatus substantially as described with reference to the drawings.

New claims or amendments to claims filed on 11 January, 1985 Superseded claims 1 New or amended claims: 1 and 7

1. Waste collection apparatus includes a container body, a blade movable reciprocally along the body to accommodate and eject waste material from the body, hydraulically-operated actuating means for resisting movement of the blade along the body during loading of the body and for driving the blade along the body during ejection of the waste material from the body, packing means for packing waste material into one end of the body against the blade, hydraulically-operated drive means for operating the packing means, control means for controlling movement of the blade during loading of the body by sensing the resistance to operation of the packing means and providing a signal to actuate movement of the blade during loading whereby the control means enables the blade to move when pressure in the packing means reaches a predetermined level.