FIELD OF THE INVENTION This invention relates to a pivot gate-type valve. More particularly, but not exclusively, this invention relates to a pivot gate-type valve for use in high-pressure slurry systems.

BACKGROUND TO THE INVENTION The applicant’s South African patent number 2017/05831 discloses a pivot gate valve, shown in Figure 1 , which comprises a valve housing 1 defining a fluid flow passage 2 therethrough, a valve closure 3 which is pivotably progressively displaceable A relative to the housing 1 , and displacing means 4 for displacing the closure 3. The displacing means 4 is connected to the closure 3 by means of a rotating connector 5 which permits the point 6 at which the displacing means 4 is connected to the closure 3 to be laterally movable relative to the closure 3, as the closure 3 displaces A operatively upwardly and downwardly, in use. Such relative lateral movement between the closure 3 and connection point 6 is needed since the displacing means 4 is rigidly mounted to the valve housing 1 and is only able to move B along a straight line as it is rotated relative to the housing 1 , with the connecting point 6 being movable along an arc C as the closure 3 is displaced upwardly and downwardly.

It has been found that once the valve has been assembled to a working state, its performance is very good. However, in order to produce a working valve has been found to be an extremely cumbersome and time-consuming process, mainly due to the fact that the tolerances need to be very precise.

OBJECT OF THE INVENTION

It is accordingly an object of the present invention to provide a pivot gate valve which, at least partially, alleviates the abovementioned disadvantage, and/or to provide a pivot valve which is a useful alternative to known valves. SUMMARY OF THE INVENTION

According to the invention, there is provided a pivot valve comprising:

- a valve housing defining a fluid flow passage therethrough for operatively receiving a fluid;

- a valve closure which is pivotably progressively displaceable, transversely to the flow passage, between a closed position, wherein the closure overlies the flow passage and closes it, whereby fluid is prevented from flowing past the closure in the flow passage, and an open position, wherein the closure is displaced, at least partially, from the flow passage whereby the flow passage is, at least partially, open and fluid is permitted to flow therein past the closure; and

- displacing means for displacing the closure between its respective open and closed positions, the displacing means being pivotably connected to the housing whereby it is able to pivot relative to the housing when the closure displaces between its open and closed positions. There is provided for the displacing means to include an arm whose operatively lower end is connected to the closure and a height adjustment mechanism for raising and lowering the arm to thereby adjust the position of the closure. The height adjustment mechanism may be operated by any one of manually, hydraulically, pneumatically, and electrically.

The inclination of the arm, with respect to the vertical, may change as the closure displaces between its open and closed positions. More specifically, the inclination of the arm, with respect to the vertical, may first increase and thereafter decrease again as the closure progressively displaces from its open position to its closed position. Similarly, the inclination of the arm, with respect to the vertical, may first increase and thereafter decrease again as the closure progressively displaces from its closed position to its open position.

There is provided for the displacing means to be pivotably connected to the housing by it being supported on a clevis that protrudes upwardly from the housing.

According to an example embodiment of the invention, the displacing means may be connected to the closure intermediate its pivot axis and a sealing portion that overlies the flow passage when the closure is in its closed position.

According to an example embodiment of the invention, the housing may include a closure slot being transverse to the flow passage wherein the closure is displaceable. There is further provided for the valve to include a valve seat in the flow passage, the valve seat including opposing annuli of resilient material, the annuli being arranged to sealingly engage each other when the closure is in its open position in order to seal the flow passage, and to receive the closure in-between them and to sealingly abut opposing sides of the closure when it is in its closed position so to seal the flow passage.

These and other features of the invention are described in more detail below.

BRIEF DESCRIPTION OF THE ACCOMPANYING DIAGRAMS

One embodiment of the invention is described below, by way of a non-limiting example only, and with reference to the accompanying drawings wherein:

Figure 1 shows a schematic sectioned side elevation of a known pivot gate valve;

Figure 2 shows a schematic perspective view of a pivot gate valve in accordance with the invention;

Figure 3 shows a schematic side elevation of the valve of Figure 2;

Figure 4 shows a schematic end elevation of the valve of Figure 2;

Figure 5 shows a schematic sectioned side elevation of the valve of Figure 2, with a closure thereof in an open position; Figure 6 shows a schematic sectioned side elevation of the valve of Figure 2, with the closure in a partially open position; and

Figure 7 shows a schematic sectioned side elevation of the valve of Figure 2, with the closure in a closed position.

DETAILED DESCRIPTION OF AN EXAMPLE EMBODIMENT OF THE INVENTION

Referring to the accompanying Figures, a pivot gate valve, in accordance with the invention, is generally designated by reference numeral 10.

The valve 10 is generally used in high-pressure slurry systems (not shown) and comprises a valve housing 12 defining a flow passage 14 therethrough for operatively receiving a fluid (not shown). The valve 10 further includes a valve closure 16 which is pivotably progressively displaceable D, transversely to the flow passage 14, between a closed position (shown in Figure 7) and an open position (shown in Figure 5). With the closure 16 in its closed position, it overlies the flow passage 14 and closes it, whereby fluid is unable to flow past the closure 16 in the flow passage 14. On the other hand, with the closure 16 in its open position, it is displaced, at least partially, from the flow passage 14 whereby the flow passage 14 is open and fluid is permitted to flow therein past the closure 16. Preferably, but not exclusively, when the closure 16 is in its open position, the flow passage 14 is open and no part of the closure 16 obstructs the flow passage 14. The valve 10 also includes displacing means 18 for displacing the closure 16 between its respective open and closed positions. The displacing means 18 is pivotably connected to the housing 12 whereby it is able to pivot E, relative to the housing 12, when the closure 16 displaces between its open and closed positions. As will be elaborated on further below, this pivoting motion E is illustrated in Figures 5 to 7.

The valve housing 12 defines a closure cavity or slot 20 therein that is orientated transverse to the flow passage 14 and provides a space wherein the valve closure 16 is displaceable. Flanges 22 are provided on opposing sides of the valve 10 which could be connected to other components (not shown), including conduits, of the high- pressure slurry system.

A valve seal or seat 24 is further provided in the flow passage 14 whereby it surrounds the flow passage 14. The valve seat 24 includes opposing annuli sleeves 24 of resilient material, the annuli 24 being arranged to sealingly engage each other when the valve closure 16 is in its open position in order to seal the flow passage 14, and to receive the valve closure 16 in-between them and to sealingly abut opposing sides of the valve closure 16 when it is in its closed position so to seal the flow passage 14. The displacing means 18 may include an arm 26 (also referred to in the industry as a spindle) whose operatively lower end 28 is connected to the closure 16 and a height adjustment mechanism 30 for raising and lowering the arm 26 to thereby adjust the position of the closure 16. The lower end 28 is connected to the closure 16 intermediate its axis of rotation and a sealing portion that overlies the flow passage 14 when the closure 16 is in its closed position. Although the mechanism 30 is illustrated to be a hand-operated mechanism, it should be appreciated that in other embodiments of the invention, the mechanism 30 could be an automated mechanism (pneumatic- or hydraulically-operated), electric, bevel gearbox mechanism, or the like. As is best shown in Figure 4, the displacing means 18 is pivotably connected to the housing 12 by it being supported on a clevis 32 that protrudes upwardly from the housing 12, whereby the mechanism 30 is able to pivot or sway on the clevis 32 as the closure 16 moves between its open and closed positions. The displacing means, and more specifically, the mechanism 30 seats on opposing pegs 34 which project inwardly towards each other from end supports 36, with the arm 26 being suspended from the mechanism 30 between the pegs 34.

Referring particularly to Figures 5 to 7, the inclination of the arm 26, with respect to the vertical, denoted by symbol a, changes as the closure 16 displaces between its open and closed positions. According to an example embodiment of the invention, the inclination a is between one (1 ) and ten (10) degrees. More preferably, the inclination a is between two (2) and six (6) degrees. Most preferably, the inclination or is about three (3) degrees. With the closure 16 in its fully open position, as shown in Figure 5, the arm 26 is orientated substantially vertically. When the arm 26 is slightly lowered, the closure 16 is displaced from its fully open position towards a partially open position wherein the closure 16 partially closes off the flow passage 14, as shown in Figure 6, and the arm 26 pivots E in one direction whereby its inclination a increases and it has a slanted orientation with respect to the vertical. As the arm 26 is further lowered, the closure 16 is displaced to its closed position, as shown in Figure 7, and the arm 26 pivots E in an opposing second direction whereby its inclination a decreases and it has a substantial vertical orientation. This pivoting movement E of the arm 26 is caused by the lower end 28 having to move along an arc F which forces the end 28 to initially move downwardly and laterally as the closure 16 is lowered from its open position. It follows that the inclination a of the arm 26 first increases and thereafter decrease as the closure 16 progressively displaces from its open position to its closed position. Similarly, the inclination a of the arm 26 first increases and thereafter decreases as the closure 16 progressively displaces from its closed position to its open position.

In use, the valve 10 is connected, via flanges 24, in a high-pressure liquid system in order to permit liquid (not shown) to flow through the flow passage 14 when the closure 16 is in its open position. When it is required to prevent liquid from flowing through part of the system where the valve 10 is located, the displacing means is utilised to displace the closure 16 to its closed position to close the passage 14.

It is envisaged that a less complex manufacturing and assembly process would be required to produce the valve 10 as opposed to the process used to produce the applicant’s corresponding valve, as described in South African patent number 2017/05831 . This means that the valve 10 could not only be produced in a shorter time but also at a lower price.

It will be appreciated by those skilled in the art that the invention is not limited to the precise details as described herein and that many variations are possible without departing from the scope of the appended claims. As such, the present invention extends to all functionally equivalent structures, methods and uses that are within its scope. For example, the closure 14 may also be a ported closure, including an open portion, which overlies the flow passage when the closure 14 is in its open position, and a closed portion, which overlies the flow passage when the closure 14 is in its closed position.

The description is presented by way of example only in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention. The words which have been used herein are words of description and illustration, rather than words of limitation.