GB2362922A

GB2362922A - Hydraulic actuator with sealing bush

Info

Publication number: GB2362922A
Application number: GB0112777A
Authority: GB
Inventors: Michael Nolan; Henry Nolan; John Nolan; Tom Nolan
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-05-25
Filing date: 2001-05-25
Publication date: 2001-12-05
Anticipated expiration: 2021-05-25
Also published as: GB0112777D0; GB2362922B; IE20000413A1

Abstract

A hydraulic actuator assembly 16 for opening and closing an aperture 18 of a vacuum tanker comprises a hydraulic ram 24 and a rod 22 extending from the hydraulic ram 24 through an opening in a tank of the tanker. The rod is connected to an aperture closure means 20 for selectively opening and closing the outlet aperture 18. The hydraulic ram 24 is mounted on the tank by a boss 28 located above the opening. A sealing bush 30 is located between the mounting means and the hydraulic ram 24 and rod 22. This assembly 16 is used in agricultural vehicles.

Description

2362922 1 Improvements in vacuum tanks and tankers The present invention

relates to vacuum tanks and tankers, for example, slurry spreaders and, in particular, to an improved hydraulic actuator assembly for opening and closing the outlet aperture of a vacuum tanker.

In general, a hydraulic actuator assembly is used to open and close the aperture on the back of a vacuum tanker from which, in use, slurry or the likeis ejected. Such a hydraulic actuator assembly and vacuum tanker is described for example in GB2215405, which by reference is incorporated herein in it's entirety. A hydraulic actuator assembly will generally utilise a hydraulic ram and a rod slidably engaged within the ram in order to raise or lower a plate or the like so as to effect opening and closing of the aperture. Such a ram includes a seal proximal the free end thereof, disposed between the ram and the rod, in order to prevent the hydraulic fluid from leaking, in use, from the ram to the external environment.

Sometimest however, the seal at the free end of the hydraulic ram can fail as a result of wear or similar mechanical fault, resulting in the hydraulic fluid, generally oil, being forced under pressure past the ruptured seal to escape from the ram. In most conventional equipment utilising hydraulic rams, the seal at the free end of the hydraulic ram or rams is located externally such that the leaking hydraulic fluid will be noticed by the operator and the necessary action taken to prevent further damage from occurring.

2 However, with such vacuum tankers as described in GB2215405, the end of the hydraulic ram from which the rod projects is engaged in a wall of the tank, with the seal therefore being in register with an opening through to the interior of the tank. Therefore, if the seal at the free end of the ram fails, the hydraulic fluid pumps, in use, directly into the tank, and such leakage is consequently not noticed by the tanker operator.

In addition, when the seal fails, if the vacuum tanker is subsequently filled with liquid and then pressurised, the liquid may be forced back past the ruptured seal and through the ram into the hydraulic fluid tank of the tractor. This can cause considerable damage to the tractor, often necessitating expensive repairs to either the tanker or the tractor, or indeed both. The problem of hydraulic fluid leakage from hydraulic actuator assemblies in vacuum tankers has remained unsolved for approximately twenty years.

The present invention has been made from a consideration of the above mentioned disadvantages and, in particular, in order to provide an improved hydraulic actuator assembly which overcomes the above mentioned problems associated with known vacuum tankers, by preventing hydraulic fluid leakage into the tanker and by preventing liquid contained within the tank from entering the actuator assembly.

According to a first aspect of the present invention there is provided a hydraulic actuator assembly for 3 operative association with an aperture closure means for selectively opening and closing an aperture of a tank, the hydraulic actuator assembly comprising a hydraulic ram; a rod slidably engaged within the hydraulic ram and extending from the hydraulic ram into an opening provided in the tank, the rod being connected, in use, to the aperture closure means; and a bush mounted externally of the tank, the bush having a through bore shaped and dimensioned to permit sliding 10 movement of the rod therethrough.

Preferably, the bush is mounted to the tank by a cylindrical boss and the bush is located at least partly within the boss.

is Preferably, the bush is substantially cylindrical in form and has a longitudinally extending through bore therein.

Preferably, the bush has a first portion whose external diameter is adapted to abut against the boss.

Preferably, the bush has a second portion whose external diameter is adapted to be a close f it in the 25 boss.

Preferably, the bush has a f irst internal bore whose diameter is adapted to provide a substantially f luid tight fit with the hydraulic ram.

Preferably, the bush has a second internal bore whose diameter is adapted to provide a substantially fluid 4 tight f it with the rod while permitting sliding movement of the rod therethrough.

Preferably, the first internal bore and the second 5 internal bore def ine a shoulder against which, in use, the hydraulic ram abuts.

Preferably, the bush has a bypass aperture in a side wall thereof which is in fluid communication with the through bore.

Preferably, the bypass aperture is disposed normally of the through bore and projects from either side thereof to the sidewall.

is According to a second aspect of the present invention there is provided a vacuum tanker comprising a tank mounted on a chassis, the chassis being capable of being releaseably attached to a tractor or other vehicle, a pump means for drawing liquid or semi-liquid material into the tank and expelling liquid or semiliquid material out of the tank, the tank having an aperture which is selectively openable and closeable by means of said hydraulic actuator assembly.

Thus, it will be seen that with a hydraulic actuator assembly or tanker of the invention, the problems associated with hydraulic fluid leaking into the vacuum tanker, and in return liquid being pumped back to the hydraulic fluid tanks of the tractor are eliminated. Both hydraulic fluid leakages from the actuator assembly and liquid returning through the actuator assembly can cause considerable damage to the tractor which can be costly to repair.

The invention will now be described further, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 is a diagrammatic side elevation of a vacuum tanker according to an embodiment of the invention; Fig. 2 is a diagrammatic end view of a hatch and hydraulic actuator assembly of the tanker of Figure 1; Fig. 3 is a longitudinal sectional view of a bush forming part of the hydraulic actuator assembly of Figure 2; Fig. 4 is an end view of the bush of Figure 3; and Fig. 5 is an enlarged sectional view of the hydraulic actuator assembly of the present invention.

Referring now to the Figure 1, a vacuum tanker 1 comprises a generally cylindrical tank 2 mounted on a chassis 4 having wheels 6. The front end of the chassis is attachable to a tractor (not shown) or the like for towing by means of a hitch 8. A conventional vacuum pump system 10 is provided for drawing liquid or semiliquid material into the tank 2 and expelling liquid or semi-liquid material out of the tank 2 through a conventional spreading unit 12 mounted on the rear end 6 of the tank 2 and connected to the tank 2 via a hatch 14, the hatch 14 being in fluid communication with the interior of the tank 2.

Referring to Figure 2, a hydraulic actuator assembly 16 is mounted at the rear of the tank 2 and is operable to selectively open or close an aperture 18 by means of substantially vertical sliding of an aperture closure plate 20, which in a lowered position occludes the aperture 18, and in a raised position is substantially clear of the aperture 18. The aperture closure plate 20, in Figure 2, is located intermediate the lowered position and the raised position. The aperture closure plate 20 is connected to a rod 22 which is slidably engaged within a hydraulic ram 24, which is located externally of the tank 2. The hydraulic ram 24 may be fed with hydraulic fluid (not shown) from the hydraulic tank (not shown) of the tractor, by means of suitable hydraulic circuitry (not shown), in any conventional manner. A threaded end 241 of the ram 24 is provided with a conventional seal (not shown) disposed at the interface between the rod 22 and the threaded end 241, in order to prevent hydraulic fluid from leaking, under pressure, from within the ram 24. Pumping hydraulic fluid into the hydraulic ram 24 draws the rod 22 inwardly thereof, thereby raising the aperture closure plate 20 to allow liquid (not shown) contained within the tank 2 to be forced therefrom through the outlet aperture 18. This is effected by reverse operation of the vacuum pump system 10 such as to pressurise the tank 2, resulting in the liquid within the tank 2 being forced through the aperture 18 in the hatch 14, to exit from the spreading unit 12.

7 The actuator assembly 16 is further provided with a return spring 26 which is arranged to bias the rod 22 outwardly of the ram 24, such that when hydraulic fluid ceases to be pumped into the ram 24, the rod 22 is forced outwardly thereof in order to effect lowering of the aperture closure plate 20, and therefore occlusion of the aperture 18. The return spring 26 is required with the present embodiment of the invention, as the ram 24 is single acting, although it will be appreciated that the ram 24 and the return spring 26 could be replaced by a double acting hydraulic ram (not shown).

Referring to Figures 2 and 5, the ram 24 is mounted to the tank 2 by means of a boss 28 secured within an outer wall 52, at the top of the hatch 14, the boss 28 being in register with an opening 36 which provides access to the interior of the tank 2, via the hatch 14. The rod 22 therefore extends from the ram 24, through the opening 36, to be substantially disposed within the interior of the hatch 14, which is in fluid communication with the interior of the tank 2. Therefore. in use, both the rod 22 and the aperture closure plate 20 are surrounded by and contacted with the liquid contained within the tank 2.

A bush 30 is mounted to and projects substantially outwardly from the boss 28 and is shown in more detail in Figures 3, 4 and 5. The bush 30 is generally cylindrical in form having a through bore 46 therein.

The bush 30 has a first portion 32 having an external diameter adapted to abut against the exterior of the 8 boss 28, and a second portion 34 adapted to be threaded into engagement with a neck 54 of the boss 28.

In conventional hydraulic actuator assemblies (not 5 shown), the bush 30 is not provided intermediate the ram 24 and the boss 28, the threaded end 241 therefore being threaded directly into the neck 54 of the boss 28, such that the threaded end 241 is in fluid communication with the interior of the boss 28, and therefore the opening 36 into the tank 2. It will therefore be appreciated that, if the seal (not shown) located at the interface between the threaded end 241 and the rod 22 fails, the hydraulic fluid being pumped from the tractor into the ram 24 will be forced past the ruptured seal (not shown), and therefore flow directly through the opening 36 into the tank 2. it will therefore be appreciated that this leakage of hydraulic fluid occurs internally of the boss 28, and is therefore not visible to the operator. The tractor may therefore empty its entire load of hydraulic fluid into the tank 2, causing considerable damage thereto, in addition to polluting the liquid contents thereof.

Furthermore, as hereinbefore described, in order to force the liquid contents of the tank 2 fromthe spreading unit 12, the tank 2 is pressurised by means of the vacuum pump system 10. However, if the seal (not shown) located at the interface of the threaded end 241 and the rod 22 has failed, reverse operation of the vacuum pump system 10 will force the liquid contents of the tank 2 through the opening 36 and ultimately into the hydraulic fluid tank of the tractor. This will obviously damage both the ram 24 9 and the hydraulic fluid tank of the tractor, thereby necessitating expensive repairs thereto.

However, with the present hydraulic actuator assembly 16, the threaded end 241 is threaded into engagement with a first internal bore 38 of the bush 30 such that the bush 30 elevates the threaded end 241 so that it is no longer in fluid communication with the opening 36 into the tank 2. The bush 30 is also provided with a shoulder 42 against which the threaded end 241 tightly abuts, in addition to a second internal bore 40 having a diameter substantially equal to that of the rod 22, such as to allow sliding movement of the rod 22 therethrough while preventing leakage of hydraulic fluid from the threaded end 241, in the event that the seal (not shown) fails. However, in the event that a quantity of the hydraulic fluid does leak from the threaded end 241, proximal the shoulder 42, it will tend to be forced, in use, downwardly between the rod 22 and the through bore 46. Therefore, the bush 30 is provided with a bypass aperture 44 which extends from, and normally to, the through bore 46 outwardly of the bush 30 on either side thereof. Therefore, referring in particular to Figure 5, any hydraulic fluid leaking- downwardly between the rod 22 and the through bore 46 will reach the bypass aperture 44 which, by providing a path of zero resistance to the hydraulic fluid, prevents the hydraulic fluid from progressing further down the second internal bore 40. The leaking hydraulic fluid will thus flow radially outwardly of the bush 30, through the bypass aperture 44 and to the external environment. The hydraulic fluid will therefore be visible to an operator who can then cease operation of the hydraulic actuator assembly 16 in order to effect repairs thereto.

In use, the bush 30 acts as an effective seal to inhibit hydraulic fluid leakage from the ram 24 into the tank 2. The bush 30 also eliminates the risk of liquid being forced back into the tractor (not shown) from the tank 2. The bypass aperture 44 allows hydraulic fluid and liquid to escape and ensures that such is visible to the operator. Thus, any hydraulic fluid leakage from the actuator or any liquid leakage from the tank 2 passes out through the bypass aperture 44. Typically, the bush 30 is made from mild steel or the like material.

is In assembling the hydraulic actuator assembly 16, the boss 28 is first mounted to the hatch 14 such as to be in register with the opening 36. The bush 30 is then engaged about the rod 22 before the rod 22 is inserted through the opening 36 into the tank 2. The bush 30 is then threaded into engagement with the threaded end 24', such as to abut tightly against the shoulder 42. The rod 22 is then passed through the boss 28 and the opening 36, to be disposed within the interior of the tank 2. The bush 30 is then threaded into engagement with the neck 54 of the boss 28, via a second portion 34 thereof, such as to provide a close fit between the bush 30 and the boss 22.

It will be appreciated from the foregoing description that the hydraulic actuator assembly 16 of the present invention is not limited to use in a mobile form such

11 as that embodied by the tanker 1, nor is it limited to use with such a tank 2 as hereinbefore described.

12

Claims

1. A hydraulic actuator assembly for operative association with an aperture closure means for selectively opening and closing an aperture of a tank, the hydraulic actuator assembly comprising a hydraulic ram; a rod slidably engaged within the hydraulic ram and extending from the hydraulic ram into an opening 10 provided in the tank, the rod being connected, in use, to the aperture closure means; and a bush mounted externally of the tank, the bush having a through bore shaped and dimensioned to permit sliding movement of the rod therethrough.

is 2. A hydraulic actuator assembly as claimed in claim 1 wherein the bush is mounted to the tank by a cylindrical boss and the bush is located at least partly within the boss.

3. A hydraulic actuator assembly as claimed in any preceding claim wherein the bush is substantially cylindrical in form and has a longitudinally extending 25 through bore therein.

4. A hydraulic actuator assembly as claimed in claim 2 or 3 wherein the bush has a first portion whose external diameter is adapted to abut against the boss.

5. A hydraulic actuator assembly as claimed in any preceeding claim wherein the bush has a second portion 13 whose external diameter is adapted to be a close fit in the boss.

6. A hydraulic actuator assembly as claimed in any preceding claim wherein the bush has a first internal bore whose diameter is adapted to provide a substantially fluid tight fit with the hydraulic ram.

7. A hydraulic actuator assembly as claimed in any preceding claim wherein the bush has a second internal bore whose diameter is adapted to provide a substantially fluid tight fit with the rod while permitting sliding movement of the rod therethrough.

8. A hydraulic actuator assembly as claimed in claim 7 wherein the first internal bore and the second internal bore define a shoulder against which, in use, the hydraulic ram abuts.

9. A hydraulic actuator assembly as claimed in any preceding claim wherein the bush has a bypass aperture in a side wall thereof which is in fluid communication with the through bore.

10. A hydraulic actuator assembly as claimed in claim 9 wherein the bypass aperture is disposed normally of the through bore and projects from either side thereof to the sidewall.

11. A vacuum tanker having a hydraulic actuator assembly as claimed in any preceding claim.

14 12. A vacuum tanker as claimed in claim 11 comprising a tank mounted on a chassis, the chassis being capable of being releaseably attached to a tractor or other vehicle, a pump means for drawing liquid or semi-liquid material into the tank and expelling liquid or semiliquid material out of the tank, the tank having an aperture which is selectively openable and closeable by means of said hydraulic actuator assembly.

13. A hydraulic actuator assembly substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

14. A vacuum tanker substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.