Cordless electric sprayer

Abstract

An electric sprayer comprising a tank having a housing extending over portions of the tank and a piston pump extending into the tank. The pump has an inlet and an outlet. Discharge equipment including a spray nozzle is mounted to an exterior surface of the housing. The discharge equipment is connected to an elastomeric tube surrounded by a coil spring which, in turn, is connected to a slender elongated tube connected to the pump outlet. A motor driven by a set of rechargeable batteries is mounted in the housing and is connected to the pump. An on/off switch electrically interconnecting the batteries and motor is mounted to an exterior surface of the housing. The discharge equipment includes portions pivotally mounted to the housing exterior surface so as to permit movement between a first inoperative position wherein the discharge equipment shields the on/off switch to a second operative position wherein the switch is exposed.

Description

BACKGROUND OF THE INVENTION

The present invention relates to sprayers and more particularly to a cordless electric sprayer.

Sprayers find extensive use in commercial, industrial, and garden applications such as for the spraying of pesticides and the like on trees and shrubs. Because such sprayers must oftentimes be used in places far removed from convenient access to a source of electric power, various non-electric spraying devices have been developed for such applications. The need has remained, however, for a convenient, portable, electrical garden spray device.

Thus, in view of the above, it is the principal object of the present invention to provide an improved spray device powered by rechargeable battery means.

A further object is to provide such a sprayer with safety means designed to prevent the inadvertent activation of the sprayer at times other than the time of desired use.

Other objects are to provide a sprayer capable of delivering the fluid to be sprayed with a reasonably constant back pressure and which limits the maximum pressure build-up in the system in the event the sprayer outlet nozzle becomes clogged.

SUMMARY OF THE INVENTION

The above and other beneficial objects are attained in accordance with the present invention by providing an improved cordless electric sprayer comprising a tank having a housing extending over portions of the tank. A piston pump extends into the tank. The pump has an inlet and an outlet. Discharge equipment including a spray nozzle is mounted to an exterior surface of the housing. The discharge equipment is connected to an elastomeric tube surrounded by a coil spring which, in turn, is connected to a slender elongated tube connected to the pump outlet. A motor driven by a set of rechargeable batteries is mounted in the housing and is operatively connected to the pump. An on/off switch electrically interconnecting the batteries and motor is mounted to an exterior surface of the housing. The discharge equipment includes portions pivotally mounted to the housing exterior surface so as to permit movement between a first inoperative position wherein the discharge equipment shields the on/off switch to a second operative position wherein the switch is exposed .

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a perspective view of an electric sprayer in accordance with the present invention;

FIG. 2 is a simplified perspective schematic of the pump and discharge equipment of the present electric sprayer;

FIG. 3 is a side elevational sectional view of the present electric sprayer;

FIG. 4 is a sectional view taken along reference lines 4--4 of FIG. 3 in the direction indicated by the arrows;

FIG. 5 is a sectional view taken along reference lines 5--5 of FIG. 3 in the direction indicated by the arrows; and

FIG. 6 is a fragmentary sectional view taken along reference lines 6--6 of FIG. 4 in the direction indicated by the arrows.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference is now made to the drawings wherein similar components bear the same reference numerals throughout the several views. In FIG. 1, the present electric sprayer 10 is shown comprising a tank 12 and housing 14. As shown in FIG. 3, the tank 12 includes a neck portion 16 defining an opening through which the liquids to be sprayed can be poured into the tank interior. A closure 18 is provided for the opening.

A piston pump 20 extends into the tank through closure 18. The pump is driven by a D-C motor 22 which, in turn, derives its power from a set of rechargeable nickel-cadmium batteries 24. The batteries and motor are mounted within the housing with the batteries connected through a suitable rectifying circuit (not shown) to terminal pins 26 which extend outside the housing. The terminal pins may be connected through a suitable connector and cord to a source of line voltage to enable recharging of the batteries as required.

Batteries 24 are connected to motor 22 through sliding contacts 28, the connection being controlled by the position of switch 30 which extends through the top surface 32 of the housing through a suitable opening 34.

The fluid within tank 12 is fed by pump 20 to discharge equipment 36 which includes a hollow wand 38 one end of which is connected to a spray nozzle 40. The opposite end of wand 38 is connected through a pivotal fitting 42 mounted on the top of the housing and interconnecting the wand 38 with tube 44 disposed within the housing. The function of this tube will be discussed in detail forthwith.

Referring to FIG. 1, it can be seen that the pivotal fitting 42 permits the wand 38 to be shifted from a first inoperative position wherein the wand overlies the top surface of the housing as shown to a second position wherein the wand is pivoted away from the housing as shown in phantom. This is an important feature of the present sprayer since when the wand is in the inoperative position, it overlies switch 30 thereby shielding the switch from accidentally being pushed when the discharge equipment is in the storage position.

Referring to FIG. 2, it can be seen that motor 22 which may be a permanent magnet type D-C motor is provided with an eccentric pin 46 connected to the motor shaft 48. The eccentric pin 46 engages the oblong opening 50 of a scotch yoke 52 thereby driving the yoke up and down in response to rotation of the shaft. The yoke 52 is connected to a piston rod 54 disposed in a cylinder 56 extending outwardly from the pump body 58. A seal 60 rigidly mounted within the cylinder is in sealing engagement with the piston rod.

An inlet port 62 and an outlet port 64 are defined in the pump body. A check valve 66 including ball 68 insures one-way flow of fluid from the tank into the body interior through the inlet port.

An elongated rigid slender tube 70 extends from the outlet port with one end connected to the port. The other end of tube 70 is connected to one end of a flexible elastomeric tube 72. The other end of tube 72, in turn, is connected to tube 44 which, in turn, is connected to the pivotal fitting 42. A coil spring 76 is wound about the elastomeric tube as shown.

Operation

In normal operation, the shifting of switch 30 to an on position makes the appropriate connection to turn on motor 22 causing eccentric pin 46 to rotate. Eccentric pin 46 drives scotch yoke 52 and hence piston rod 54 in a vertical reciprocating fashion. The upward motion of the piston rod draws fluid into the pump body through check valve 66. Downward motion of the piston decreases the volume of the interior chamber of cylinder 56 and thus expels fluid through outlet port 64 into the elongated slender tube 70. The mass of fluid in tube 70 is traveling away from the pump body with some velocity. The momentum of the fluid in the tube is therefore the product of this mass and velocity. As the piston begins to rise, the volume of the chamber 74 beneath the seal increases. This increase in volume causes the fluid pressure in the chamber to decrease which, in turn, causes two things to happen:

1. It opens the check valve and draws more fluid to the pump chamber, and

2. Decreases the momentum of the fluid in tube 70.

As the piston reaches the top of its travel and starts downward, it again closes the check valve and adds momentum to the fluid in tube 70. Since the mass of fluid in the tube remains constant, the variations in momentum as the piston travels up and down are reflected in variations in fluid velocity in the tube. The use of tube 70 thus allows the pump to function effectively without a check valve on the outlet side of the pump. This improves the reliability of the pump and simplifies the cleaning of fluid passages, etc. In addition, the use of a momentum tube, such as tube 70, instead of a positive check valve at the outlet of the pump allows the pump to deliver more flow than the piston displacement. Thus, the piston pump of the present application is not a positive displacement pump but rather it behaves as a variable displacement pump. This happens because the momentum of the outgoing fluid is used to draw fluid into the piston chamber through the check valve at the inlet.

The elastomeric tube 72 thus receives fluid from the rigid tube 70 with a variable velocity. As a result, tube 72 swells in diameter in response to increases in the pressure in the system. The swelling continues until tube 72 is constrained by the coil spring 76 surrounding it. Tube 72 then oscillates with its diameter and length changing so as to damp out the pressure and velocity fluctuations in order to deliver fluid to the nozzle 40 with a relatively constant back pressure. The coil spring also serves to clamp the ends of the tube to prevent the tube from slipping off its connections with tubes 44 and 70. In this regard, the ends of the coil springs are biased radially inwardly so as to urge the ends of the elastomeric tubes to tightly engage tubes 44 and 70.

The changes in length and diameter of the elastomeric tube are reflected as changes in its internal volume. These changes in internal volume are particularly advantageous in the event the discharge equipment becomes blocked downstream from the elastomeric tube. In that event, the piston pumps a volume of fluid through the momentum tube 70 into the elastomeric tube 72 which swells to accept the volume of fluid. The elastomeric tube then shrinks in volume and pushes fluid back down through the momentum tube as the piston rises and the piston chamber increases in volume. Thus, in this mode of operation, (i.e., when the discharge equipment is blocked) the maximum pressure build-up in the system is limited with corresponding reductions in the mechanical loads on the drive components and reductions in electrical loads.

Thus, in accordance with the above, the aforementioned objects and advantages are attained.

Claims

Having thus described the invention what is claimed is:

1. An electric sprayer comprising: a tank; a piston pump extending into said tank, said pump comprises a body portion, an elongated cylindrical member extending from said body, a piston rod disposed for movement within said cylinder member, an inlet port defined in said body, a one-way check valve mounted in said inlet port, an outlet port defined in said body; discharge equipment including a spray nozzle connected to said pump outlet; an elongated slender rigid tube extending from said pump outlet for connection with said discharge equipment; an elongated elastomeric tube interposed between and connected to said rigid tube and said discharge equipment; a coil spring mounted about and coextensive with said elastomeric tube; a housing extending over portions of and connected to said tank; and a motor mounted in said housing, said motor being connected in driving relationship to said pump.

2. The electric sprayer in accordance with claim 1 further comprising a rechargeable battery mounted in said housing, on/off switch means mounted to an exterior surface of said housing, said switch means electrically interconnecting said battery and said motor; and said discharge equipment includes portions pivotally mounted to said housing exterior surface to permit movement between a first inoperative position wherein said discharge means shields said on/off switch to a second operative position wherein said switch is exposed.

3. The electric sprayer is accordance with claim 1 wherein said coil spring includes first and second ends wound about respective first and second ends of said elastomeric tube, said elastomeric tube first end is disposed about one end of said rigid tube, said elastomeric tube second end is disposed about portions of said discharge equipment and said coil spring ends are biased radially inwardly whereby to cooperate in securing said elastomeric tube to said rigid tube and discharge equipment.