GB2333572A

GB2333572A - A motor drive comprising at least two motors

Info

Publication number: GB2333572A
Application number: GB9825749A
Authority: GB
Inventors: Arrigo Zanella; Gianpietro Cazzola
Original assignee: VALEX SpA
Current assignee: VALEX SpA
Priority date: 1997-12-02
Filing date: 1998-11-24
Publication date: 1999-07-28
Also published as: ES1042395U; FR2772206A3; GB9825749D0; DE29821580U1; ES1042395Y

Abstract

A motor drive for electrically actuated machines and/or tools, comprising at least two electric collector motors (12,13) which are kinematically connected to a rotating shaft (17) for the actuation of a working part (18) of a electrically actuated machine and/or tool. Various embodiments are disclosed.

Description

MOTOR DRIVE FOR ELECTRICALLY ACTUATED MACHINES AND/OR TOOLS The present invention relates to a motor drive for electrically actuated machines and/or tools.

More particularly, the motor drive can be adapted for gardening tools and for all tools or machines, whether portable, transportable or fixed, in which a working part is motorized electrically (for example drills, grinders, highpressure, motorized cleaners, motor-driven compressors and other electrical appliances).

Internal-combustion engines and electric motors are currently used for gardening tools such as lawn mowers, hedge trimmers, edge trimmers and leaf blower-aspirators.

In their kinematic layout, the working part (for example the rotating blade of a lawn mower) is directly connected to the output shaft of the motor or is connected thereto by means of a belt or gear transmission.

The range offered commercially by each manufacturer for a same tool is currently differentiated substantially in terms of the different power rating; this differentiation is achieved by increasing or decreasing the size of the motor.

Changing the size of the motor clearly means changing the dimensions of the structure of the machine (for example the body of the lawn mower) in order to adapt it to the change in bulk, or trying to adapt to the various motors to an identical structure (which is extremely difficult in many cases).

This clearly has negative repercussions on production, on production costs and on raw materials store management and finished product store management.

The aim of the present invention is to provide a motor drive for electrically actuated machines and/or tools which eliminates the above-mentioned drawbacks types.

Within the scope of the above aim, a consequent primary object of the invention is to provide a motor drive which, power ratings being equal, is more compact than current motor drives and is more simple in terms of application.

Another important object of the invention is to provide a motor drive which allows greater flexibility in the management of the power levels installed on each model of garden equipment or electric power tool.

Another important object of the invention is to provide a motor drive which as a whole is cheaper than conventional ones.

This aim, these objects and others which will become apparent hereinafter are achieved by a motor drive for electrically actuated machines and/or tools according to the present invention, characterized in that it comprises at least two electric collector motors which are kinematically connected to a rotating shaft that actuates a working part of an electrically actuated machine and/or tool.

Advantageously, the kinematic connection is provided by means of a gear transmission or by means of at least one flexible transmission element.

Further characteristics and advantages of the present invention will become apparent from the following detailed description of some embodiments thereof, illustrated by way of non-limitative example in the accompanying drawings, wherein: Figure 1 is a schematic perspective view of a lawn mower which contains a motor drive according to the invention; Figure 2 is a schematic perspective view of a hedge trimmer in which a motor drive according to the invention is installed; Figure 3 is a schematic side view of a second embodiment of a motor drive according to the invention; Figure 4 is a schematic top view of the motor drive of Figure 3; Figure 5 is a schematic side view of a third embodiment of a motor drive according to the invention; Figure 6 is a schematic top view of the motor drive of Figure 5; Figure 7 is a schematic top view of a fourth embodiment of a motor drive according to the invention; Figure 8 is a schematic side view of a fifth embodiment of a motor drive according to the invention; Figure 9 is a schematic top view of the motor drive of Figure 8; Figure 10 is a schematic perspective view, in phantom lines, of the body of a bench grinder provided with the motor drive according to the invention; and Figure 11 is a schematic perspective view, in phantom lines, of the body of a portable drill provided with the motor drive according to the invention.

With reference to the above Figure 1, a motor drive 11 is installed in a lawn mower 10 and is composed of two electric collector motors, designated respectively by the reference numerals 12 and 13, which in this case are of the DC type. Respective pinions 14 and 15 are keyed on the output shafts of the motors and mesh, in diametrically opposite positions, with a driven gear 16 which is keyed to a shaft 17 of a working part 18 of the lawn mower. The working part is constituted by a rotating blade with two mutually opposite half-arms.

The transmission ratio is a reduction.

In the case being considered of a DC motor drive an adapted power source, such as an electric current accumulator of the rechargeable type is present on board the lawn mower 10.

The power source may also be remote, for example accommodated in a container which can be carried on the back or on a shoulder-belt by the user.

In other cases it is possible to provide collector motors of the AC type and the power can be drawn directly from the mains.

Practical tests have shown that, contrary to common technical thinking, i.e., that it is not conceivable to apply two motors which are rigidly coupled to the same working shaft, this coupling is instead actually possible when using two collector motors.

None of the feared braking of one motor by the other, as normally thought, has in fact been observed; rather, a simple adaptation of one motor with respect to the other has been observed.

Moreover, the torque is always the sum of the torques delivered by the motors also if they are different.

Accordingly, on each driving gear 14 and 15 the torque is a fraction of the output torque and the teeth that can be used are smaller and cheaper than the teeth necessary for a single motor with twice the torque.

Two driving gears meshing on the same driven gear also entail a greater number of meshing teeth and their diametrically opposite arrangement eliminates radial thrusts due to the transmission of motion on the main transmission side.

In the case of three motors, the installation must of course be symmetrical, arranging one motor at 120 sexagesimal degrees to the other.

Smaller gears also entail a reduction in the cost of the entire transmission, contrary to common thinking, according to which costs increase automatically by providing two motors.

With reference now to the above-described Figure 2, a hedge trimmer is schematically shown, generally designated by the reference numeral 110, wherein a motor drive 111 is installed which like the preceding one comprises two electric collector motors, designated respectively by the reference numerals 112 and 113.

In this case also, the pinions 114 and 115, keyed on the output shafts of the motors 112 and 113, mesh in diametrically opposite positions of a driven gear 116.

The driven gear 116 is connected by means of an eccentric element 117 to a working part of the hedge trimmer 110, which in a per se known manner is conveniently constituted by a reciprocating blade 118.

The same remarks made regarding the lawn mower 10 also apply to the motor drive 111 of the hedge trimmer 110.

With reference to the above-described Figures 3 and 4, in a second embodiment a motor drive for electrically actuated machines and/or tools, according to the present invention, is generally designated by the reference numeral 210 and is composed of two electric collector motors, respectively designated by the reference numerals 212 and 213, which in this case are of the DC type.

Respective toothed pulleys 214 and 215 are connected to the output shafts of the electric motors 212 and 213 and mesh, in diametrically opposite positions, with a toothed belt 216 which is arranged therebetween.

A driven toothed pulley 217 meshes with the belt 216 at a region which is interposed between the toothed pulleys 214 and 215 of the electric motors 212 and 213.

The driven toothed pulley 217 is connected to the shaft 218 of a working part which is not shown in the above figures for the sake of simplicity.

The transmission ratio is a reduction.

In this embodiment, the motor drive 210 must be backed by an adapted power source for the electric motors 212 and 213, such as for example an electric power accumulator of the rechargeable type.

The power source may also be remote, for example accommodated in a container which can be carried by the user on his back or with a shoulder-belt.

In other cases it is possible to provide collector motors of the AC type and power may be drawn directly from the mains.

In some cases it is possible to use tensioning devices of the per se known type for the transmission belt.

As in the previous cases, practical tests have shown that contrary to common technical thinking, i.e., that it is not conceivable to apply two motors which are coupled to the same working shaft, this coupling is instead actually possible when using two collector motors.

None of the feared braking of one motor by the other, as normally thought, has in fact been observed; rather, a simple adaptation of one motor to the other has been observed.

Moreover the torque is always the sum of the torques delivered by the motors also if said motors are different.

Accordingly, on each driving toothed pulley 214 and 215 the torque is a fraction of the output torque and the belt can have a smaller cross-section (and there can be a plurality of belts in parallel) than necessary for a single motor with twice the torque.

It is also evident that other equivalent embodiments can be provided by using motor drives whose element for transmission between the gears of the motors and the working part is a belt or cable which transmits motion by simple friction or, as an alternative, a chain.

In these cases, the pulley system uses pulleys of different kinds, including sprockets in the case of chains.

The described motor drive can of course be applied to all kinds of electric tool or portable or transportable electric machine.

Use of flexible elements having a smaller cross-section also provides a reduction in the overall cost of the transmission, contrary to common thinking, according to which the provision of two motors automatically leads to a cost increase.

With particular reference to Figures 5 and 6, a third embodiment of a motor drive for electrically actuated machines and/or tools is generally designated by the reference numeral 310 and comprises a first pair and a second pair of electric collector motors of the DC type, which are not shown for the sake of simplicity in the figures.

Respective toothed pulleys 314 are connected to output shafts 312 of the first pair of electric collector motors and are coupled, in diametrically opposite positions, to a first toothed belt 316 which is arranged therebetween.

Correspondingly, respective toothed pulleys 315 are connected to output shafts 313 of the second pair of electric collector motors and mesh, in diametrically opposite positions, with a second toothed belt 317 which is arranged therebetween.

In this embodiment, the toothed pulleys 314 of said first pair are arranged on a plane which is parallel to, and lies below, the plane formed by the pulleys 315 of the second pair.

A driven toothed pulley 318 simultaneously meshes with both of said first and second toothed pulleys 316 and 317 and is arranged so that it is interposed both between the two toothed pulleys 314 of the first pair and between the pulleys 315 of the second pair.

The driven toothed pulley 318 in fact has two races, with a height which allows it to mesh simultaneously both with said first toothed belt 316 and with said second toothed belt 317.

The driven toothed pulley 318 is connected to a shaft 319 of a working part which is not shown in the above figures for the sake of simplicity.

In this configuration, in particular, the motors of each pair form, with respect to the shaft 319 of the working part whereto said driven pulley 318 is connected, an arrangement which is respectively designated by the reference numeral 311a for the first pair and by the reference numeral 311b for the second pair.

In particular, the arrangement 311a of the first pair is perpendicular to the arrangement 311b of the second pair.

It is evident that in other embodiments the driven toothed pulley connected to the shaft of the working part can mesh simultaneously with a plurality of belts arranged on parallel planes, each belt being driven by a pair of motors.

With particular reference to Figure 7, a motor drive for electrically actuated machines and/or tools in a fourth embodiment is designated by the reference numeral 410 and is composed of two electric collector motors of the DC type which are not shown in the figures for the sake of simplicity.

Respective toothed pulleys 414 and 415 are connected to the output shafts, designated by the reference numerals 412 and 413, of the electric motors and mesh with a toothed belt 416 which is arranged between the pulleys 414 and 515.

A driven toothed pulley 417 meshes with the toothed belt 416.

In particular, in this case the driving toothed pulleys 414 and 415 and the driven toothed pulley 417 are arranged at the corners of a triangle formed by the toothed belt 416, which is closed in a loop.

The driven toothed pulley 417 is connected to the shaft 418 of a working part, whic Is not illustrated for the sake of simplicity in the above figures and whereto it transmits the driving torque.

With particular reference to Figures 8 and 9, a motor drive according to the present invention in a fifth embodiment is generally designated by the reference numeral 510 and comprises two electric collector motors, which are not shown in the above figures for the sake of simplicity and in this case are of the DC type.

Respective toothed pulleys 514 and 515, shown schematically in Figures 8 and 9, are connected to output shafts of the electric motors.

Correspondingly, a driven toothed pulley 517 is connected to a shaft of a working part, not shown in the above figures for the sake of simplicity, and is conveniently interposed between the two toothed pulleys 514 and 515 of the motors.

In particular, in this embodiment the toothed pulleys 514 and 515 are arranged on parallel planes one below the other and are mutually opposite with respect to the position of the driven toothed pulley 517.

Each one of the toothed pulleys 514 and 515 meshes with a corresponding toothed belt 516 which is arranged between the respective toothed pulley and the driven toothed pulley 517.

With particular reference to the above-described Figure 10, a bench grinder (transportable electric power tool) is generally designated by the reference numeral 611 and contains a motor drive which is composed of two electric collector motors 613 and 614. Respective toothed pulleys 615 and 616 are connected to output shafts of the motors.

The pulleys 615 and 616 are arranged in diametrically opposite positions with respect to a driven toothed pulley 617 which is operatively connected to a working part 618.

A toothed belt 619 kinematically connects the pulleys 615, 616 and 617.

With particular reference to Figure 11, a portable drill is designated by the reference numeral 710 and contains a motor drive which is composed of two electric collector motors 713 and 714. Respective toothed pulleys 715 and 716 are connected to output shafts of the motors and are arranged in diametrically opposite positions with respect to a driven toothed pulley 717.

The driven toothed pulley 717 is connected to a chuck 718 of the drill.

A toothed belt 719 kinematically connects the pulleys 715, 716 and 717.

In practice it has been observed that the aim and objects of the present invention have been achieved.

The provision of a dual motor drive constituted by motors wherein each one has a half of the necessary power in fact allows to achieve reduced bulk and therefore easier installation inside machines.

The same also applies to multiple-motor drives.

The arrangement of the driving wheels (pulleys or gears) with respect to the driven wheels allows, for some configurations, to eliminate imbalances and provides balancing of the thrusts affecting the driven shaft.

A plurality of driving gears coupled to the driven gears entails having more meshing teeth for an equal output torque and allow to have smaller teeth with dimensions adapted for lower power levels, since the total power of the unit is the sum of the individual power rating of each motor.

The fact that the pulleys and belts can be provided so as to withstand a smaller load, delivered torques being equal, entails a cost reduction thereof and therefore of the entire motor drive.

Finally, it should be noted that the management of the power level of each machine, for example for gardening (lawn mower, hedge trimmer, string edge trimmer, blower-aspirators with bladed impeller, with a dual function of aspiratingblowing and shredding the aspirated material by means of sharp edges), or by means of electrically actuated tools, can be performed in a very flexible way by increasing or decreasing the number of motors, the total power being the sum of the power level of each individual motor.

A plurality of small motors finally allows easier installation.

All the details may be replaced with other technically equivalent elements.

In practice, the materials used, so long as they are compatible with the contingent use, as well as the dimentsions, may be any according to requirements.

The disclosures in Italian Utility Model Applications No. PD97U000085 and PD98U000087 from which this application claims priority are incorporated herein by reference.

Claims

1. A motor drive for electrically actuated machines and/or tools, characterized in that it comprises at least two electric collector motors which are kinematically connected to a rotating shaft for the actuation of a working part of an electrically actuated machine and/or tool.

2. The motor drive according to claim 1, characterized in that a kinematic connection between said motors is provided by means of a gear transmission.

3. The motor drive according to claim 2, characterized in that a driving gear is connected to the output shaft of each motor and meshes with the teeth of a driven gear which is connected to the rotating driving shaft of the working part.

4. The motor drive according to claim 1, characterized in that a kinematic connection between said motors is provided by means of at least one flexible transmission element.

5. The motor drive according to claim 4, characterized in that said flexible transmission element is a belt.

6. The motor drive according to claim 5, characterized in that said belt is provided with teeth.

7. The motor drive according to claim 4, characterized in that said flexible transmission element is a chain.

8. The motor drive according to claim 4, characterized in that a driving wheel is connected to the output shaft of each one of said electric motors and engages said at least one flexible element, a driven wheel being connected to the rotating shaft of said working part and engaging said flexible element.

9. The motor drive according to claim 8, characterized in that said driving wheel engages simultaneously at least two flexible elements, one for each motor.

10. The motor drive according to claim 8, characterized in that said driving wheels and said driven wheel are arranged at corners of a triangle and engage said flexible element.

11. The motor drive according to claim 8, characterized in that each one of said driving wheels engages a respective flexible element, each one of said flexible elements engaging said driven wheel.

12. The motor drive according to claim 1, characterized in that said electric collector motors are of the DC type and are connected to an accumulator or battery for electric power supply on board the corresponding electrically actuated machine and/or tool.

13. The motor drive according to claim 1, characterized in that said electric collector motors are of the DC type and are connected to a remote accumulator or battery for electric power supply.

14. The motor drive according to claim 1, characterized in that said electric collector motors are of the AC type.

15. The motor drive according to claim 1, characterized in that said working part is constituted by a rotating blade of a lawn mower.

16. The motor drive according to claim 1, characterized in that said working part is constituted by a reciprocating blade of a hedge trimmer which is coupled to said driven shaft by means of a device for converting rotary motion into reciprocating motion.

17. The motor drive according to claim 1, characterized in that said working part is constituted by a rotating string of an edge trimmer.

18. The motor drive according to claim 1, characterized in that said working part is an impeller of a garden aspirator and/or blower.

19. A motor drive for electrically actuated machines and/or tools, according to one or more of the preceding claims, and substantially as herein described with reference to the accompanying drawings.