GB2088532A - Hydraulic selector valve - Google Patents

Abstract

hydraulic system of an agricultural tractor is adapted to fit directly to the tractor auxiliary hydraulic interface and to be fitted directly with one or more directional control valves feeding auxiliary devices. The supply from the tractor hydraulic pump enters the chamber (13) and is directed by way of spool (14), controlled by lever (5), to either the existing hydraulic accessories through passage (11), or to chamber (15), from where it passes to the directional control valves and the auxiliary accessories. A return line (16,12) is permanently connected. <IMAGE>

Description

SPECIFICATION Hydraulic selector valve The invention relates to a hydraulic selector valve, and is concerned particularly with a valve which will allow the provision of auxiliary hydraulic services from the hydraulic system of an agricultural tractor.

Most agricultural tractors have a hydraulic system incorporating a recirculatory oil system having a reservoir tank and oil pump operated by the tractor engine. Generally, the pump may drive various hydraulically-operated implements which may be coupled to a rear linkage. Auxiliary hydraulic devices may be coupled to the tractor system via an interface to which oil supply and return pipes may be coupled.

Each auxiliary device generally requires a directional control valve and the pipe-work from the tractor interface to each directional control valve is cumbersome and time consuming to assemble. Also, if an auxiliary external supply pump is to be used optionally, additional complexity is introduced into the pipe-work.

The present invention seeks to provide an improvement whereby auxiliary hydraulic devices and an auxiliary pressure supply therefor may readily be interconnected with the tractor hydraulic system.

According to the invention there is provided a selector valve unit for the hydraulic system of an agricultural tractor, the tractor having an auxiliary interface with (a) a supply port from the tractor hydraulic pump; (b) a return port for hydraulic fluid; and (c) an inlet portfor hydraulic fluid supply to auxiliary devices, the selector valve unit being adapted to fit directly to the interface and having ports communicating with ports (a), (b) and (c) respectively, the selector valve unit being further adapted to be fitted directly with one or a plurality of banked directional control valves, the selector valve unit having a supply port (d) which communicates with an inlet portforthe directional control valve or valves and a return port (e) which communicates with a return port for the directional control valve or valves; the selector valve unit having an auxiliary pressure supply port (f) for coupling to an auxiliary hydraulic pump and a manually operable spool valve having at least first and second positions where, in the first position the spool valve provides a first inter-connection which couples together the supply port (a) with the inlet port (c) and in the second position isolates the first inter-connection and provides a second interconnection between the supply port (a) and the supply port (d) and channels are provided in the selector valve unit for coupling the auxiliary pressure supply port (f) with the supply port (d) and for coupling the return port (e) with the return port (b).

Preferably a non-return valve is included at the auxiliary pressure supply port (f).

In a preferred embodiment of the invention the spool valve has a third position in which both said first and said second inter-connections are effected simultaneously.

In a particularly preferred embodiment, the present invention provides specifically for a selector valve unit which adapts the interface on the top of the gear-box cover of a Massey Ferguson (Registered Trade Mark) agricultural tractor to one or a plurality of banked hydraulic directional control valves of the kind known by the designation Vapormatic Series 80.

The invention will further be described with reference to the accompanying drawings of which; Figure 1 is a side elevation of a selector valve unit in accordance with the invention; Figure 2 is an end elevation of the valve unit of Figure 1; Figure 3 is a plan view of the valve unit of Figures 1 and 2; Figure 4 is a cross-sectional view taken at 'A-A' of Figure 3; Figure 5 is a hydraulic circuit diagram of the selector valve unit of Figures 1 to 4, and Figure 6 is a cross-sectional view corresponding to Figure 4 but of a modified form of the selector valve unit; Figure 7 is a perspective view of an arrangement incorporating the invention and having remotecontrolled directional-control valves; and Figure 8 is a perspective view of the Figure 7 arrangement connected also to an auxiliary pump of the tractor.

Referring to Figures 1 to 3 the unit illustrated is for adapting the interface on the top of the gear-box cover of a Massey Ferguson (Registered Trade Mark) agricultural tractor to the Vapormatic Series 80 hydraulic directional control valve, which is a bankable spool valve for effecting control of hydraulic equipment coupled thereto. The gear-box cover of the tractor is shown at 1 and the position of a Series 80 directional control valve is shown at 2. The arrangement fits to the gear-box cover of the tractor and there is the usual linkage to change gears (not shown).

The selector valve unit includes a spool valve housing 4 which has a manual control lever 5 and an inlet for an auxiliary pressure feed. The Series 80 directional control valve 2 may be one of a series of banked valves which are sandwiched between the gear control block 7 and a Series 80 outlet end plate 8. As shown in the drawings, only one control valve 2 is included. The assembly is fixed by three studs 9 which are of a length appropriate to accommodate the required number of control valves. An outlet 10 is provided to be connected to the reservoir tank of an auxiliary hydraulic fluid system if such an auxiliary system is used.

The tractor has a hydraulic system including a reservoir tank for hydraulic oil and pump driven by the engine. Principally, the hydraulic system is used to operate hydraulic equipment attached to a rear linkage of the tractor. Referring to Figure 4 there is shown at 11 the port which is coupled to the inlet of the rear linkage equipment. At 12 there is shown the return port for the tractor hydralic system. The inlet port which provides pressure from the tractor hydraulic pump is not shown specifically but is coupled to a chamber 13.

The control lever 5 is coupled to a spool 14 which, when in the position shown, couples the chamber 13 to the port 11. In this configuration, the tractor pump is coupled to the inlet of the rear linkage and there is no inter-connection between chamber 13 and the ports 15 which are the inlet ports of the Series 80 directional control valves. When lever 5 is pushed forward to the position indicated at 5a in Figure 1, the spool is moved back and shuts off the interconnection between chamber 13 and port 11. Instead chamber 13 is coupled to the ports 15. Thus, inlet pressure is provided from the tractor pump to the directional control valves. From the directional control valves there are couplings to any hydraulic equipment which is to be controlled as auxiliary devices to the tractor.It will be seen that since there are possibly a number of valves 2, then a corresponding number of auxiliary devices can be run simultaneously from the internal pump of the tractor.

Fluid from the auxiliary devices is returned via the valves 2 to return channels 16 which are permanently coupled to the return port 12.

A particularly important feature of the arrangement described with reference to the drawings is that an auxiliary hydraulic system independent of the tractor system can be coupled readily to supply or supplement the auxiliary equipment via the control valves 2. This is made possible by the provision of the auxiliary inlet port 6 and the auxiliary return port 10 which are coupled to the supply and return conduits of the auxiliary pumping system respectively. Under normal conditions the return port 10 may be blocked off, the fluid being returned via channels 16 to the tractor reservoir, and the auxiliary pump being arranged to draw fluid from the tractor reservoir. Port 10 is provided for allowing a return pipe to be fitted if required, in the event that the restriction of the return via the valve unit is too great.

Figure 5 shows the hydraulic circuit diagram of the system where the tractor supply port is shown at 17 coupled via the spool 14 either to the rear linkage port 11 or to the directional control inlet ports 15, depending on the position of the spool. The auxiliary pressure inlet port 6 is connected permanently to ports 15 and the directional control valve outlet ports 16 are connected permanently to the return port 12 of the tractor hydraulic system. The two positions of the spool 14 are controlled positively by a springloaded ball and detent arrangement 18.

Referring now to Figure 6 there is shown a modification of the spool valve. The same reference numerals are used in Figure 6 as in Figure 5 where appropriate. The principal difference is that in the Figure 6 embodiment there are three possible posi tions for the spool of the valve. In Figure 6 the spool is shown in the central position where the inlet pressure chamber is coupled both the the rear linkage inlet port 11 and to the inlet ports 15 of the directional control valves. In this way both the rear linkage equipment and any auxiliary devices coupled to the directional control valves can be operated simultaneously.

In this embodiment the spool incorporates a non-return valve comprising a ball 20 in an internal bore 21. The ball co-operates with a seat 22 to prevent return of fluid from inlet 11 to chamber 13 when the spool is in the position shown.

When the spool is moved to the left from the position shown in Figure 6, bore 24 is blocked by portion 25 of the spool and the inter-connection between chamber 13 and inlet ports 15 is thereby cut off. At the same time, portion 26 of the spool clears bore 27 and the inter-connection between chamber 13 an inlet 11 becomes direct, by-passing the ball valve.

When the spool is moved to the right from the position shown in Figure 6, portion 28 of the spool enters the bore 27, thereby blocking off the interconnection between chamber 13 and the port 11.

The inter-connection between chamber 13 and ports 15 remains.

The selector valve comprises a shell moulded and machined body containing a hardened and ground control spool. The spool is sealed with a 'O'-ring at each end.

Figure 7 is a perspective view of an arrangement including a selector valve unit 4a coupling the tractor hydraulic sustem to two potential auxiliary devices.

In the drawings, the couplings are terminated by four quick-release connectors 30. The selector valve unit has mounted to ittwo Series 80 directional control valves 2a, 2b. Instead of having control levers mounted on the control valves after the manner of Figure 1, the control valves are manually operated from levers 34,35, via flexible cable couplings. In Figure 7 the inlet 6 for auxiliary pressure supply is shown blocked off.

Figure 8 shows an arrangement similar to Figure 7 wherein, however, auxiliary fluid supply is taken from an inlet line 31 from an auxiliary pump (not shown) coupled to the tractor engine. Line 31 includes a non-return valve 32 and is connected to inlet 6. A return line 33 is coupled to the outlet port 10 and returns to the auxiliary pump. Typically, the normally-provided fluid pump supplies fluid at the rate of 6 gallons per minute, but with the auxiliary pump coupled to the system via the selector valve inlet, a fluid supply rate of typically 13 gallons per minute is possible. The hydraulic power available is thus significantly increased.

It will be seen that with the arrangement described the selector valve unit allows the user to mount a bank of directional control valves directly to the tractor gear-box casing without the use of external pipe work. The selector valve constitutes a combined isolator valve and interface. The valve allows the tractor hydraulics to function simultaneously on a number of auxiliary devices.

Claims (4)

1. A selector valve unit for the hydraulic system of an agricultural tractor; the tractor having an auxiliary interface with (a) a supply port from the tractor hydraulic pump; (b) a return port for hyd raulic fluid; and (c) an inlet port for hydraulic fluid supply to auxiliary devices, the selector valve unit being adapted to fit directly to the interface and having ports communicating with ports (a), (b) and (c) respectively, the selector valve unit being further adapted to be fitted directly with one or a plurality of banked directional control valves, the selector valve unit having a supply port (d) which communicates with an inlet for the directional control valve or valves and a return port (e) which communicates with a return port for the directional control valve or valves; the selector valve unit having an auxiliary pressure supply port (f) for coupling to an auxiliary hydraulic pump and a manually operable spool valve having at least first and second positions where, in the first position the spool valve provides a first inter-connection which couples together the supply port (a) with the inlet port (c) and in the second position isoiates the first inter-connection and provides a second inter-connection between the supply port (a) and the supply port (d) and channels are provided in the selector valve unit for coupling the auxiliary pressure supply port (f) with the supply port (d) and for coupling the return port (e) with the return port (b).

2. A selector valve unit as claimed in claim 1 wherein a non-return valve is included at the auxiliary pressure supply port (f).

3. A selector valve unit as claimed in claim 1 or claim 2 wherein the spool valve has a third position in which both said first and second inter-connections are effected simultaneously.

4. A selector valve unit substantially as hereinbefore described with reference to the accompanying drawings.