GB2288782A

GB2288782A - Waste collection apparatus

Info

Publication number: GB2288782A
Application number: GB9408397A
Authority: GB
Inventors: David Mackrill; Michael John Howard
Original assignee: MACKRILL DAVID ENG Ltd
Current assignee: MACKRILL DAVID ENG Ltd
Priority date: 1994-04-28
Filing date: 1994-04-28
Publication date: 1995-11-01
Also published as: GB9408397D0

Abstract

Waste Collection Apparatus is equipped with means for collecting, compressing and carrying waste for subsequent ejection and disposal. The apparatus includes a container body 8, a blade 9 moveable along the body to accommodate and eject waste material from the body, hydraulically operated actuating means (Figs. 1 and 3) 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 (not shown) for packing waste material into one end of the body against the blade, hydraulically operated drive means for operating the packing means, and control means for controlling hydraulic movement of the blade during loading of the body. The position of the blade along the container body and is sensed by sensors 10 and 11 and a valve changes the resistance to movement of the blade in dependance on the blade position. Allows the material to be packed to a greater density over part of its length. <IMAGE>

Description

Waste Collection Apparatus This invention relates to refuse collection apparatus equipped with means for collecting, compressing and carrying waste for subsequent ejection and disposal.

In our prior British patent specification No. 2152898 there is described and shown waste collection apparatus which includes a container body, a blade movable reciprocally along the body under hydraulic control 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 hydraulically movement of the blade during loading of the body by sensing the hydraulic pressure in the drive means for the packing means and hence the resistance to operation of the packing means and providing a hydraulic signal to actuate movement of the blade during loading whereby the control means enables the blade to move when said hydraulic pressure in the packing means reaches a predetermined level.

By the arrangement described in British patent specification 2152898 it is possible to ensure that an even compaction of compressed waste takes place throughout the length of the collection body. In some cases, particularly when it is desirable to place more of the weight of the contents of the body in the forward area of the body it is useful to pack the waste material at a higher density over one portion of the length of the body compared with another portion.

An object of the invention is to provide waste collection apparatus which is an improvement over existing apparatus and is capable of meeting the above requirement.

According to one aspect of the invention there is provided control means for the waste collection apparatus which is able to sense the position of the blade along the container body generating a signal according to said position, the control means further comprising valve means to change the resistance to movement of the blade, the valve means being actuated according to the position of the blade along the container.

Further features of the invention will appear in the following description given, by way of example only and with reference to the drawings in which: Fig. 1 is a schematic diagram of a hydraulic system, Fig. 2 is a schematic vertical section through the collector body of waste collection apparatus, and Fig. 3 is a schematic diagram of an electrical circuit.

Referring to the drawings and firstly to Fig. 1 there is shown a control valve assembly 1 and a multistage hydraulic ejector ram 2. The valve assembly 1 is arranged in accordance with the disclosure in our patent specification 2152898. The hydraulic ram 2 is a multistage ram of the kind also described in our specification 2152898.

Interposed between the valve and the ram 2 is a supplementary circuit having check valves 3 and 4, a pilot operated check valve 5, an adjustable relief valve 6, shown by way of example, set at 30 bar, and a two position directional valve 7 which is operated by oppositely directed solenoids a and b.

The spool of the valve is locatable by detents.

Energisation of solenoid a of valve 7 causes the spool of the valve 7 to move to the position shown in Fig. 1 and is held in this position by its detent, even if the solenoid is deenergised. In this condition port P of valve 7 is connected to port A and the blanked port B is connected to port T.

Accordingly hydraulic fluid exhausting from the ejector ram 2 whilst it is under compaction is inhibited from returning to valve 1 by the closed pilot check valve 5, but returns via port P to port A in the valve 7, through the check valve 3 and then to valve 1. Whilst the valve is in this position the entire system operates in accordance with the arrangement described in patent specification 2152898.

When solenoid b of the valve 7 is energised, the spool of the valve moves to the right and is held in this position by detent means. The port P of the valve 7 is now connected to the blanked port B and port A is now connected to the port T.

Hydraulic fluid exhausting from the ejector ram 2 is now inhibited by the pilot check valve 5 and by the port P connected to the blanked port B. The only return path for the fluid to the valve 1 is through the relief valve 6. Thus a higher back pressure is created in the ejector ram and hence the ejector blade, and a higher compaction force has to be applied to the waste material entering the container and a higher compaction is obtained.

When the ejector ram 2 is extended by the admission of hydraulic fluid the pilot check valve 5 permits free flow of fluid from the valve 1 to the full bore of the ejector ram 2.

Under retraction of the ejector ram 2 by the hydraulic system, hydraulic fluid leaves valve 1 at a port CA and flows into the annulus of the ram 2. A pilot signal from this line, indicated by a dotted line d, is fed to the pilot check valve 5 opening the valve and allowing fluid from the ram full bore to return to the valve 1 and back to the fluid reservoir.

The provision of the check valve 4 is to provide a decompression bleed from the solenoid valve to the reservoir whilst compaction is taking place and to prevent any malfunction of the valve 7 due to pressure build up.

Referring now to Fig. 2 there is shown a side view of a waste collection body 8 internally of which is located an ejector blade 9. Packing means for loading waste material into the body 8 is located to the rear of the body and may be of the kind described in British specification 2152898.

The roof of the body 8 carries proximity switches 10 and 11 which may be inductive switches and one of the switches 11 is located towards the rear of the body whilst the switch 10 is located some one third of the distance along the body from the rear end. Both switches are electrically normally open and are arranged to close when the ejector blade passes them.

Although the switches 10 and 11 are located in the position shown their positions are determined by the densities required over the length of the body 8.

Fig. 3 shows an electrical circuit diagram including solenoid valves a and b associated with the valve 7, the two switches 10 and 11, two normally open relays 12 and 13 and a switch in the form of a momentary contact push button 14. Power supply is from the vehicle batteries connected at 20.

A typical operational cycle of the apparatus is as follows.

At the start of loading, the ejector blade is moved to the rearward end of the body at position 9' and towards the end of its travel it passes switch 11 which is energised and in turn energises relay 12. The contacts of relay 12 close and a voltage is applied to the solenoid b of the valve 7 thereby selecting the relatively higher back pressure resisting movement of the blade along the body.

The packing means is operated to pack waste material into the rear open end of the body against the blade and when the compaction pressure reaches a sufficiently high level the hydraulic fluid in the ram 2 is discharged thereby permitting the ram 2 to contract towards the forward end of the body.

Although the blade 9 moves away from the switch 11 the relatively high compaction pressure setting is maintained by the valve 7, the spool remaining in the position selected by the relay 12.

When the movement of the blade 9 reaches a position along the body adjacent the switch 10 the relay 13 is energised and its contacts close which applies a voltage to the solenoid a of the valve 7. The port P is opened to port A and a lower compaction pressure setting is selected. Compaction of waste in the body and movement of the blade 9 in the forward direction continues at the lower setting until the container body 8 is full. Thereafter the body is ready for ejection of its contents by a reverse movement of the ram 2.

Within the body 8 the waste towards the front end of the body, i.e. the left hand end as shown in Fig. 2, is denser than it is over its rearward portion. Accordingly a higher proportion of the weight of the contents of the body is transferred towards the front of the vehicle.

It will be understood that, during the travel of the ejector blade from the switch 11 towards the switch 10, if the back pressure in the hydraulic fluid is too high to allow movement of the blade 9 a switch 14 may be operated to place the system in the lower back pressure mode.

The invention will find particular application in taking advantage of an increase in the permissible gross vehicle weight which legislation has recently permitted in which the extra capacity arises out of an increased rating of the twin steer front wheels of the vehicle. Since the overall dimensions of the vehicle and the body have remained substantially unchanged, the ability to take extra load on the front of the body takes advantage of the increased permissible capacity.

Claims

CLAMS

1. Waste Collection Apparatus of the kind described comprising control means which is able to sense the position of the blade along the container body generating a signal according to said position, the control means further comprising valve means to change the resistance to movement of the blade, the valve means being actuated according to the position of the blade along the container.