Field of the Invention

The invention relates to a valve control mechanism, and, especially to a valve control mechanism for use with a tanker outlet valve.

Background to the Invention

A tanker, or tanker truck, is generally formed of several compartments that are connected to a main header section, with the header comprising at least one outlet valve. The compartment containing the liquid to be discharged will have a foot valve, arranged upstream of the outlet valve therein, when viewed in the direction of discharge.

Tankers are often employed to convey flammable materials, such as fuel and, it is essential to follow all necessary steps in a methodical manner when loading and unloading tankers to ensure the safety of the operator and anyone else in the surrounding area. To that end, the brakes of the vehicle must be applied to avoid the tanker moving during loading and unloaded and electrical systems must be shut down to reduce the risk of sparks igniting any fuel being loaded or unloaded. Incorrectly loading and unloading the tanker can have devastating effects and where the operator may have driven for some time, there is an increased risk of the operator being tired and inadvertently missing steps of the loading and unloading process. The foot valve in the tanker is normally controlled using a hydraulic feed, so that the valve can be opened and closed from a position external to the tanker.

One known problem in tanker unloading is that when the outlet valve, also called an “API valve” is fully open and gravity discharge is being performed, sudden closure of the outlet valve can result in considerable damage to the tanker. This is because during discharge, liquid can be passing through the outlet valve at a velocity of 3 metres a second, which is around 1,400 litres a minute, thereby resulting in the discharging fluid having a large amount of kinetic energy. The correct way to arrest the flow of liquid is to close the foot valve before closing the outlet valve. If the foot valve is not closed beforehand, the kinetic energy of arresting the flow of liquid instantaneously is sufficient to stretch bolts and cause significant damage to the outlet valve.

When loading a tanker of this nature, if the foot valve is not opened before filling, or is insufficiently opened, there can be a build-up of static electricity on the surface of the liquid, due to the friction created by the liquid pressing against the spring-loaded valve plate. Clearly, a combination of static electricity and liquid fuel product can have disastrous consequences.

Summary of the Invention

Accordingly, the present invention is directed to a bottom loading tanker valve control mechanism, wherein the tanker comprises a foot valve and a tank outlet valve, wherein, the tank outlet valve is controlled by an actuator and wherein the actuator is coupled to the tank foot valve, such that when tank outlet valve is opened by movement of the actuator, the tank foot valve is opened thereafter upon movement of the same actuator and, when the tank outlet valve is closed by movement of the actuator, the tank foot valve is closed before the tank outlet valve is closed upon movement of the same actuator.

Thus, the present invention links the operation of the foot valve to operation of the tank outlet valve. This is particularly advantageous because linking the two valves in this way reduces the risk of the operator forgetting to open or close the valve in the correct order. In turn, this creates safer loading and unloading of the tanker and reduces the risk for damage to the tanker, spillage of the contents and risk of injury. Controlling the foot valve, which normally involves a piston valve, using the same actuator as the outlet valve assists with the smooth loading and unloading of the tanker contents.

The closure of the foot valve prior to closure of the tank outlet valve creates a partial vacuum up-stream of the tank outlet valve, which arrests the flow, thereby reducing the flow rate and, in turn, reducing the force exerted upon the tank outlet valve by the outgoing liquid as it closes.

It is preferable that the foot valve is operated via a foot valve control, and it is more preferable that the actuator is in contact with a foot valve control via a cam. The foot valve control may employ a piston and cylinder arrangement, in which case the cam may control the position of the piston within the cylinder. The use of a cam allows operation of the foot valve to be directly linked to operation of the actuator. Thus, by employing a particular shape of cam, the opening and closing of the foot valve can be conducted in a pre-determined and known manner, so that it can be opened and closed progressively as the tank outlet valve is also opened and closed.

Where a cam is employed, it may be advantageous that the actuator is connected to the tank outlet valve via a tank valve arm and wherein the cam is pivotally connected to the tank valve arm. Having the cam pivotally linked to the tank valve arm allows for the motion of the cam to be controlled and the force to be more consistent.

In one arrangement, the cam has a first arcuate section with a first radius and a second arcuate section with a second radius, with the first radius being larger than the second radius. The use of a cam with a first and second radius allows the foot valve to remain closed until the tank outlet valve is partially open. This ensures that liquid is able to pass through the tank outlet valve prior to it being dispensed via the foot valve in the tank in which it is stored. The first radius is employed to keep the foot valve closed before the second radius of the cam opens the foot valve. Therefore, the foot valve is operated in a known manner to ensure that it is opened, and closed, in the correct order and when the tank outlet valve is in the correct position.

In a preferred arrangement, the foot valve is controlled via a foot valve control that is linked to the cam, and, more preferably, the foot valve control comprises a piston and cylinder arrangement. It is particularly advantageous that the piston and cylinder arrangement comprises an air inlet, along with a first air outlet and a second air outlet, and wherein the position of the piston within the cylinder allows fluid communication between either the air inlet and the first air outlet or the air inlet and the second air outlet.

Linking the foot valve to a foot valve control allows the foot valve to be controlled from a position that is remote from the foot valve itself. Where this is the case, it is useful to hydraulically or pneumatically control the foot valve from the foot valve control, because such an arrangement removes the need for electrical contacts, thereby reducing the risk of sparks. Such control of the foot valve can be provided by having an air inlet, which may in some arrangements be a different gas from air, and two air outlets and wherein the foot valve control opens the foot valve by directing air from the inlet to a specific outlet. Thus, air is provided to the foot valve from the foot valve control to open the foot valve. Removing the supply of air to the foot valve can allow it to close, although it will be appreciated that supply of air from the second outlet may be used to close the foot valve. A useful mechanism for adjusting the flow of air from the foot valve control is the use of a piston and cylinder arrangement with the first and second air outlets being positioned axially along the cylinder and a seal there between so that air flow can be directed to either the first or the second air outlets upon adjustment of the piston within the cylinder.

Brief Description of the Drawings

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

Figures la and lb show sectional views in different planes of a valve arrangement in accordance with the present invention in a first position;

Figures 2a and 2b show the views of Figure la and lb with the valve arrangement in a second position; and Figures 3a and 3b show the views of Figures 1 and lb with the valve arrangement in a third position.

Detailed Description of Exemplary Embodiments

Figures la to 3b show a valve arrangement 10 comprising a housing 12, in which are located a tank outlet valve 14 and a foot valve control 16.

The tank outlet valve 14 comprises a circular aperture 18 within a first side of the housing 12 through which the contents of the tanker can be dispensed, the aperture 18 having tapered sides 20 on the internal side of the housing 10. The outlet valve 14 is provided with a circular blocking member 22, the circumference of which is provided with tapered sides 24 that correspond with the tapered sides 20 of the aperture 18. The blocking member 22 is also provided with a seal 26 about its circumference, such that when the blocking member 22 is received within the aperture 18, a seal is created to prevent the fluid of fluid through the aperture 18.

The internal surface of the blocking member 22 is connected to a tank valve arm in the form of a control shaft 28 that extends through the housing 12 and protrudes from a second side of that housing 12, the second side of the housing 12 being opposite the first side of the housing and the aperture 18. The control shaft 28 is connected to the blocking member 20 by a threaded connection 30, with the respective parts of the blocking member 22 and the control shaft 28 being provided with respective threaded portions. The control shaft 28 is provided with a seat element 32 towards the second side of the housing 12 and internal thereto, with a biasing compression spring 34 being arranged coaxially around the control shaft 28. A first end of the biasing spring 34 is in contact with the seat element 32 and the opposite end of the biasing spring 34 is in contact with the blocking member 22, such that the blocking member 22 is biasing towards the aperture 18. Thus, if no counter force is provided to counteract the biasing spring 34, the blocking member 22 will rest in the aperture 18, thereby putting the outlet valve 14 into a closed position and preventing fluid flow therethrough. The foot valve control comprises a cylindrical body 40 with an air inlet 42, a valve insert 44 and a first air outlet 46 and a second air outlet 48. The valve insert 44 moves axially within the cylindrical body 40 and has a first position (Figure lb) in which the air is directed to the first air outlet 46 and a second position (Figure 3b) in which the air is directed to the second air outlet 48. Thus, in the first position, the air inlet 42 is in fluid communication with the first air outlet 46, and in the second position, the air inlet 42 is in fluid communication with the second air outlet 48. Seal members 50 are arranged to direct the air flow and accordingly. The valve insert 44 is biased to be in the first position, thus, when displaced, it will naturally return to the first position unless held in the displaced position. The valve insert 44 is provided with a top element 52 that houses a wheel member 54 that protrudes from the top element 52 and is free to rotation about its axle.

An actuation lever 60 is provided on the housing 12 that rotates an actuator axle 62 that extends into the housing 12. The actuator axle 62 is fixedly connected to an actuation arm 64 that extends from the actuator axle 62, such that when the actuator axle 62 rotates, the actuation arm 64 is rotated.

A cam 70 is provided within the housing 12 and the cam 70 is pivotally connected to the actuation arm 64 and to the control shaft 28. The cam 70 comprises a first elongate projection 72 that connects between the actuation arm 64 and the control shaft 28 and a second elongate projection 74 that extends in the same rearward direction as the first elongate projection 72, but that is offset from the first projection 72. The second projection 74 has a first section 76 that is arcuate and has a first profile and a second section 78 that has a second profile. The profile of the first section 76 and/or the profile of the second section 78 is, preferably, arcuate, particularly for the second section 78.

The second projection 74 of the cam 70 contacts the wheel member 54 of the top element 52 of the valve insert 44. As a result, when the cam 70 is moved, the wheel member 54 is rotated and, due to the shape of the second projection 74, the valve insert 44 can be displaced upon movement of the cam 70. When installed, when the actuation lever 60 is operated, the actuation arm 64 operates the control shaft 28 via the cam 70 so that the control shaft 28 is displaced within the housing 12. This movement acts against the biasing spring 34, thereby moving the blocking member 22 into the housing 12 towards the second side of the housing 12 and opening the tank outlet valve 14. At the same time, movement of the cam 70 displaces the valve insert 44 of the foot valve control 16. Due to the shape of the second projection 74 of the cam 70, displacement of the valve insert 44 does not occur during movement of the cam whilst the first section 76 of the second projection 74 presses against the wheel member 54; however, as the second section 78 of the second projection 74 acts against the wheel member 54, the valve insert 44 is moved within the cylindrical body 40, which directs the airflow from air inlet 42 away from the first air outlet 46 and into the second air outlet 48. As the air flow passes into the second air outlet 48, the foot valve of the tanker is opened to allow the flow of fluid from within the tanker to the tanker outlet valve 14.

When discharging of the tanker is completed, the actuation lever 60 is operated in the other direction, which, moves the second projection 74 of the cam 70 so that the part in contact with wheel member 54 is changed from the second profile 78 to the first profile 76. This redirects the air flow from the second air outlet 48, back into the first air outlet 46, thereby closing the foot valve. At the same time, the tanker outlet valve 14 is being closed; however, the cam 70 ensures that the foot valve is closed in advance of the blocking member 22 engaging the aperture 18. Thus, the foot valve is closed before the tanker outlet valve 14, thereby ensuring that the flow of fluid is arrested prior to the tanker outlet valve 14 being completely closed. This arrangement reduces the force of the liquid being dispensed from the tanker prior to the tanker outlet valve 14 fully closing, thereby reducing the force thereupon and reducing the risk of damage to the tanker outlet valve 14 and the housing 12.

It will be appreciated that the air flow in the foot valve control 16 may be replaced with a different gas, for example nitrogen. Additionally, the shape of the second projection 74 of the cam 70 may be adjusted to change the timing of the closure of the foot valve in relation to the closure of the tank outlet valve 14.