Toy Gun With Pneumatic to Hydraulic Pressure Magnifier

Abstract

A toy gun includes a hydraulic cylinder, a nozzle from which water from the hydraulic cylinder can be expelled, and a hydraulic piston movable in the hydraulic cylinder. The hydraulic cylinder is of a certain surface area. A pneumatic piston is movable in a pneumatic cylinder and is connected to the hydraulic piston. The pneumatic piston has a surface area that is larger than that of the hydraulic piston. Upon triggering, compressed air is delivered to the pneumatic cylinder and pressure induced in the hydraulic cylinder is magnified substantially by the ratio of the two surface areas.

Description

BACKGROUND OF THE INVENTION

The present invention relates to toy guns. The invention more particularly, although not exclusively, relates to water-shooting toy guns exploiting pneumatic pressure to propel water from a nozzle.

Due to the compressible nature of gases, compressed air is a relatively inefficient propellant for firing water from toy guns. For example, an effective 90 psi of hydraulic pressure behind the nozzle is very difficult to achieve using stored pneumatic pressure in a toy gun to be operated by children. However, 50 psi for example is relatively easy to achieve as a stored pneumatic firing pressure.

SUMMARY

Briefly stated, high hydraulic firing pressure is achieved in a toy gun primed with relatively low pneumatic pressure.

There is disclosed herein a toy gun, comprising:

a hydraulic cylinder;

a nozzle from which water from the hydraulic cylinder can be expelled;

a hydraulic piston movable in the hydraulic cylinder and having a hydraulic surface area;

a pneumatic cylinder;

a pneumatic piston movable in the pneumatic cylinder and connected to the hydraulic piston, the pneumatic piston having a pneumatic surface area that is larger than the hydraulic surface area; and

means for presenting compressed air to the pneumatic cylinder.

Preferably, the toy gun further comprises a reservoir for receiving water and compressed air above the water, and an inlet valve enabling one-way flow of water from the reservoir to the hydraulic cylinder.

Preferably, the toy gun further comprises a priming pump for compressing the air above the water in the reservoir.

Preferably, the toy gun further comprises a fluid switch adapted upon trigger-activation to release compressed air from the reservoir to the pneumatic cylinder.

Preferably, the toy gun further comprises a conduit extending between the priming pump and the reservoir, and wherein the fluid switch communicates air from a conduit to the pneumatic cylinder.

Preferably, the toy gun further comprises a trigger acting upon the fluid switch.

Preferably, the toy gun further comprises a nozzle valve activated by the trigger.

Preferably, the pneumatic piston is linked or connected to the hydraulic piston by a connecting rod.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic cross-sectional elevation of parts of a toy gun in a pre-priming configuration;

FIG. 2 is a similar schematic cross-sectional elevation of the same parts at the commencement of priming;

FIG. 3 is a similar schematic cross-sectional elevation of the same parts at a commencement of firing configuration;

FIG. 4 is a similar schematic cross-sectional elevation of the same parts at a completion of firing configuration;

FIG. 5 is a similar schematic cross-sectional elevation of the same parts in a post-firing configuration;

FIG. 6 is a similar schematic cross-sectional elevation of the same parts at a trigger-released post-firing configuration; and

FIG. 7 is a similar schematic cross-sectional elevation of the same parts in a partially water-depleted condition ready for re-priming.

DETAILED DESCRIPTION

In the accompanying drawings there is depicted schematically the internal components 10 of a toy gun.

A reservoir 11 is sealed by a cap via which water can be replenished. Extending upwardly into the reservoir 11 is a riser tube 18. The riser tube 18 extends almost to the top of the reservoir 11 so that its exit is above water level. The riser tube 18 is connected to a junction 17. A priming conduit 16 extends from the junction 17 to a primer 13. Primer 13 comprises a reciprocating handle 14 connected to a priming piston 15 which incorporates a one-way valve 43. The one-way valve 43 at the priming pump prevents backflow of air from the riser tube 16 to the pump.

Also attached to the junction 17 is a fluid switch 20 activated by a trigger 19.

Located beneath the reservoir 11 is a double cylinder 12 comprising a small diameter hydraulic cylinder 25 and a large diameter pneumatic cylinder 23. A hydraulic piston 24 slides within the hydraulic cylinder 25 and is sealed against the internal cylinder wall 25 by an O-ring. Similarly, a pneumatic piston 22 slides within the pneumatic cylinder 23 and has an O-ring to seal against the internal cylinder wall of the pneumatic cylinder 23. Pistons 22 and 24 are fixed to one another by a rigid connecting rod 26. The surface area of the hydraulic piston 24 is smaller than the surface area of the pneumatic piston 22.

A firing conduit 21 extends between the fluid switch 20 and the pneumatic cylinder 23.

At the front of the hydraulic cylinder 25 there is a hydraulic firing chamber 30. A nozzle 31 extends from the hydraulic firing chamber 30 to open space.

Immediately behind the nozzle 31 is a nozzle valve 32 from which there extends a firing rod 28. The firing rod 28 is sealed through an aperture of the hydraulic firing chamber 30 and biased into the closed configuration by a nozzle valve return spring 33.

The firing rod 28 has a stopper 40 at its exposed tail end.

The fluid switch 20 comprises a manifold casing having a manifold rod 34 extending longitudinally through it. Attached to the manifold rod 34 is a trigger 19. A trigger return spring 35 biases the trigger to the configuration depicted in FIG. 1.

Attached to the trigger 19 is a pull rod 41 having at its distal end a catch 27 through which the firing rod 28 extends.

The manifold rod 34 is sealed into the manifold by a pair of O-rings 37 and 38. These O-rings are fixed with respect to the manifold casing and the manifold rod 34 slides with respect to the O-rings. The manifold rod 34 has a circumferential or annular recess 39.

The air gap between manifold rod 34 and the fluid switch (manifold) casing forms the pneumatic exhaust port 36.

In the drawings, the letter “W” represents water or other hydraulic liquid and a letter “A” represents pneumatic gas such as air. For convenience, the words “water” and “air” are used.

In use, water is poured into the reservoir 11 and the cap seals the reservoir 11. The handle 14 of the priming pump 13 is reciprocated to build up pneumatic pressure in the priming conduit 16, junction 17, riser tube 18 and in the air above the water in the reservoir 11.

Hydraulic pressure in the water of the reservoir rises accordingly. As the inlet valve 29 is a one-way valve, water has flowed from the reservoir 11 into the hydraulic firing chamber 30 and into the hydraulic cylinder 25 ahead of the hydraulic piston 24. The air trapped between piston 22 and conduit 21 will be vented to atmosphere through exhaust port 36 via the gap between the O-ring 37 and the annular recess 39 in the manifold rod 34. The nozzle valve 32 is closed and continued reciprocation of handle 14 builds up hydraulic and pneumatic pressure in the system.

When trigger 19 is activated, it moves past the position of FIG. 2 to the position shown in FIG. 3. The catch 27 of the pull rod 28 pulls against the stopper 40. Accordingly, the firing rod 28 opens the nozzle valve 32 against the return spring 33. At the same time, the annular recess 39 forms a flow channel around the O-ring 38 so that the pressurised air at the junction 17 passes rapidly through the firing conduit 21 into the pneumatic cylinder 23.

If the pneumatic pressure behind the piston 22 is say 50 psi, the ratio of the diameter of pistons 22 and 24 will produce a correspondingly increased hydraulic pressure in the water of hydraulic cylinder 25. Such pressure might be around 90 psi. The connecting rod applies an equal and opposite force between the pistons. As the movement is dynamic in nature, there will of course be some inefficiency due to slight frictional and leakage losses when the nozzle is opened. The net force on the connecting rod 26 is to the left. As a result, both pistons 22 and 24 move in unison to the left to cause a rapid jet of water through the nozzle 31.

When the trigger 19 is released as shown in FIG. 5, the pistons 22 and 24 come to rest at the left and nozzle valve 32 is sealed again. Air pressure inside the reservoir 11 will push water into hydraulic firing chamber 30 again via inlet valve 29 as shown in FIG. 6. In this configuration, the manifold rod 34 has moved to the left, so that the annular recess 39 has formed a flow channel around at O-ring 37 so that air substantially at atmospheric pressure behind the pneumatic piston 22 escapes to atmosphere via exhaust port 36.

The system then reverts to the configuration depicted in FIG. 7 whereat the volume of water remaining in the reservoir 11 has diminished by the amount which escaped via a nozzle 31. The system can continue to be primed as a solid portion of the manifold rod 34 has sealed against O-ring 38.

It should be appreciated that modifications and alterations obvious to those skilled in the art are not to be considered as beyond the scope of the present invention.

Claims

1. A toy gun, comprising:

a hydraulic cylinder;

a nozzle from which water from the hydraulic cylinder can be expelled;

a hydraulic piston movable in the hydraulic cylinder and having a hydraulic surface area;

a pneumatic cylinder;

a pneumatic piston movable in the pneumatic cylinder and connected to the hydraulic piston, the pneumatic piston having a pneumatic surface area that is larger than the hydraulic surface area; and

means for presenting compressed air to the pneumatic cylinder.

2. The toy gun of claim 1, further comprising a reservoir for receiving water and compressed air above the water, and an inlet valve enabling one-way flow of water from the reservoir to the hydraulic cylinder.

3. The toy gun of claim 2, further comprising a priming pump for compressing the air above the water in the reservoir.

4. The toy gun of claim 3, further comprising a fluid switch adapted upon trigger-activation to release compressed air from the reservoir to the pneumatic cylinder.

5. The toy gun of claim 4, further comprising a conduit extending between the priming pump and the reservoir, and wherein the fluid switch communicates air from a conduit to the pneumatic cylinder.

6. The toy gun of claim 5, further comprising a trigger acting upon the fluid switch.

7. The toy gun of claim 1, further comprising a nozzle valve activated by the trigger.

8. The toy gun of claim 1, wherein the pneumatic piston is linked or connected to the hydraulic piston by a connecting rod.