GB2080921A

GB2080921A - Vibration damping handle

Info

Publication number: GB2080921A
Application number: GB8119224A
Authority: GB
Original assignee: Seto Kazuto
Current assignee: Seto Kazuto
Priority date: 1980-06-27
Filing date: 1981-06-22
Publication date: 1982-02-10
Also published as: GB2080921B; DE3124227A1; JPS594264B2; JPS5754087A; SE8103994L; AU7191181A

Abstract

A vibration-damping handle, for a hand-operated electro-mechanical or pneumatic tool or for control of vibrating machines, comprises a vibration receiving member (1) firmly connectable via a connecting member (2) to a vibrating body such as a housing of-a tool. A pair of first vibration-damping bodies (4, 5) are secured to the respective ends of the vibration receiving member, and a pair of second vibration-damping bodies (8,9) are disposed on a common axis outside the first vibration-damping bodies and each connected via a respective resilient damper member (6, 7) to the associated first vibration- damping body. A pair of third vibration-damping bodies (12, 13) are disposed between the first vibration- damping bodies, on the common axis, and secured to a hand-grip (3). A tie- rod (20) connects vibration-damping bodies, being secured to the second and third vibration-damping bodies, and passing through a bore in the first vibration-damping bodies <IMAGE>

Description

SPECIFICATION Vibration damping handle The present invention relates to a vibration damping handle for use with a device having a body which vibrates, when operating, such as a hand-operated electro-mechanical pneumatic tool, or the control member of a vehicle, e.g. a crane, bulldozer, fork-lift truck or motor cycle.

For the prevention of transmission of vibration to a handle, a member of elastic material such as a damper may be disposed between the vibration source and the handle. Even if a substantial vibration damping effect is obtainable by the use of such elastic material, the handle operation tends to be too indeterminate, due to the flexibility of the elastic material, and in the actual operation of a tool or machine there may be some tendency to wobble or stagger as it is difficult to perform proper centering.

One object of the present invention is to provide a vibration damping handle which is substantially rigidly connected to a vibration source for control purposes, but which is nevertheless capable of effectively damping hazardous vibration.

The invention consists in a vibration damping handle comprising an elongate vibration receiving member for connection at an intermediate point to a device having a body that vibrates, when operating, a pair of first vibration-damping bodies being secured to opposite ends of said vibration receiving member, a pair of second vibrationdamping bodies disposed one outside each respective one of said first vibration-damping bodies on a common axis and each connected via a respective resilient damper member to the associated first vibration-damping body, a pair of third vibration-damping bodies disposed on said common axis between said first vibration-damping bodies, a hand-grip member secured to said pair of third vibration-damping bodies, and tie-rod means linking each said second vibration-damping body to its associated third vibration-damping body through a bore in the associated first vibration-damping body.

The term "vibration-damping body" is intended to refer to a body having a mass of such a magnitude that its presence has a significant effect upon the vibrational characteristics of the assembled handle.

The invention will now be described with reference to the drawings, in which: Figure 1 is a simplified exploded schematic view of parts of one exemplary embodiment of a handle constructed in accordance with the present invention; and Figure 2 is a cross-sectional schematic side view of this embodiment shown assembled, and with a minor modification.

An elongate vibration receiving member 1 is designed to be attached to a connecting member 2 at a point intermediate between its ends to receive from a source (not shown) producing hazardous vibrations, such as a casing of an electro-mechanical or pneumatic tool, or a machine powered by a small internal combustion system, in which case the handle might be a control member. In the illustrated embodiment, the vibration receiving member 1 is in the shape of a channel, but any other shape may be used to divide and distribute the received vibrations separately to the right and left ends, 1 a and 2a, respectively, and so toward a hand-grip member 3.

A pair of first vibration-damping bodies 4 and 5 are secured to the ends 1 a and 2a respectively, these bodies being preterably symmetrical to each other, and having the same mass. They may be secured by welding or brazing, as illustrated, as this is simple and secure. However, other securing means such as bolts or rivets may be used.

The first vibration-damping bodies 4 and 5 are provided with respective bores 4a and 5a. These bores are preferably circular in cross-section, but other cross-sections may be used, such as square, hexagonal, or rectanguiar cross-sections.

Each of the first vibration-damping bodies, 4 and 5, may most simply be in a form of a block, as shown in Figure 2, but it may be cup-shaped with its hollow portion 4b or Sb, packed with a rubber or a semi-rigid synthetic resin material, as shown in Figure 1. The cup-shaped portion is preferably made of a metal. This modified construction can be applied to second and third vibration-damping bodies which will be described hereinafter.

Respective resilient damping members, which in this embodiment are in the form of springs 6 and 7, are located on receiving portions 4c and Sc integrally formed on the respective first vibrationdamping bodies 4 and 5, outwardly directed to locate the springs 6 and 7 respectively. The spring receiving portions are shown as male coupling flanges but they may be female grooves. The above-mentioned bores 4a and 5a extend straight through the respective spring receiving portions 4c and 5c.

The damper springs 6 and 7 are preferably mutually identical in material and shape, and are disposed mutually symmetrical about the handle.

In the illustrated embodiment, they are constructed in a form of coil springs as a typical example. However, they may be in the form of leaf springs, an assembly of coned disc springs, bellows, etc. or provided by rubber or equivalent material.

A pair of second vibration-damping bodies, 8 and 9, preferably made of metal, have respective bores 8a and 9a on a common longitudinal axis passing through the centre of each respective vibration-damping body, and these bodies have spring receiving portions 8b and 9b to locate the associated ends of the springs 6 and 7 respectively.

Screw-threaded holes, 8c and Sc are provided normal to the common axis in the second vibration-damping bodies 8 and 9, and are designed to receive securing screws, 10 and 11 respectively, and thereby to secure the second vibration-damping bodies 8 and 9 to the respective ends of a tie-rod member 20. In order to reinforce and ensure the attachment, it is possible to provide, a similar securing means at the lower side in addition to the screw securing means illustrated at the upper side.

A pair of third vibration-damping bodies 12 and 1 3 are provided, each with a centre bore 1 2a and 1 3a respectively, and with screw threaded holes, 1 2b and 1 3b respectively, normal to the common axis, to receive securing screws 14 and 1 5 respectively. The structures and fundamental functions of these bodies are the same as described with reference to the second vibrationdamping bodies 8 and 9. The bodies 12 and 13 are themselves secured at their outer faces, 1 6 and 17, to the inner wall of a tubular hand-grip 3.

The securing may be effected by adhesive layers, or any other known and effective securing means, possibly using screws or rivets. The hand-grip 3 and the tie-rod 20 are not shown in Figure 1.

Having thus described the construction of the handle its function will now be described.

A hazardous vibration from a vibration source, e.g. a housing of an electro-mechanical tool, will be transmitted via the connecting member 2 to the first vibration-damping bodies 4 and 5 substantially with the initial amplitude and frequency. However, if the ends 1 a and 1 b in a form of an arm each have a certain elasticity, then they can themselves provide a certain degree of vibrationdamping.

In the vibration system to the left hand side of a centre reference line C, the vibration from the body 4, damped by the spring 6, is transmitted to the second vibration-damping body 8. Then, the vibration from the body 8 is transmitted via the left-hand half of the tie-rod 20 to the third vibration-damping body 12, whereupon the body 12 vibrates to an extremely reduced degree. In a usual hand-operated tool, the diameter of the tierod member 20 may be from 5 to 8 mm.

Likewise, in the vibration system to the righthand side of the reference line C, the vibration from the first vibration-damping body 5 damped by the spring 7 is transmitted to the second vibration-damping body 9, and then via the righthand half of the tie-rod 20 to the third vibrationdamping body 13, whereupon the body 13 vibrates to an extremely reduced degree. The portion of the tie-rod 20 between the bodies 12 and 13 may be omitted, as the hand-grip 3 couples these bodies, as illustrated in Figure 2.

By properly selecting the mass of each vibration-damping body and of each damper, spring, or tie-rod, and the spring constant of each spring or other resilient member, and allowing for adjustment of the bodies 8, 9, 12 and 1 3 on their tie-rod means, it is possible to have a vibration node A (i.e. a point where the vibration is minimum) located at or close to the centre point. It is considered that an inverse vibration phase state exists in both the left and right vibration systems along the tie-rod 20, and particularly the vibration phase of the third vibration-damping bodies 1 2 and 13, is inverse. However, altemative means may be used to secure the bodies, for example, threaded central bores can engage with a threaded tie-rod, and lock nuts provided.It is not essential to allow for adjustment in all cases, and these bodies can be positively fixed to their tie-rod means if so desired.

The hand-grip 3 is only connected to the third vibration-damping bodies 12 and 13, and accordingly, it is physically and mechanically isolated from other points of the vibration systems, particularly at its ends. The central portion of the hand-grip 3 corresponds to a vibration node A where the vibration is theoretically zero, and accordingly the hand-grip receives only a very limited vibration at most.

Experiment has indicated that an initial vibration can be damped to a level of from 1/10 to 1/30th of its initial value.

If an excessive force is applied to the hand-grip, the tie-rod 20 may come into direct contact with the inner walls of the bores of the first vibrationdamping bodies 4 and 5, whereby a hazardous vibration could be partially directly transmitted to the tie-rod 20. However, even in such a case, the vibration should be damped down to a level of 1/10th of the initial vibration. In all cases, positive control relative to the common axis defined by the tie-rod 20 is ensured by the strength of the tie-rod and of the mutually opposing resilient damping members 6 and 7.

Having thus described a simple form of a vibration model, wherein the vibration systems to the left and right of the centre line C are mutually symmetrical, it should be understood that, depending upon the nature of the vibratiori to be transmitted via the connecting member 2 from the vibration source, the left and right hand vibrationdamping systems may be of mutually asymmetrical construction if the design requires such properties.

The initial vibration may be rather complex, including various types of vibrations which differ in amplitude, frequency and in the plane or piano of vibration. Experimental results show that even complex vibrations can be effectively dampecrby a construction in accordance with the present invention, wherein the left and right hand vibration damping systems are exactly or substantially mutually symmetrical, and accordingly practical constructions that are concentric and coaxial can be used.

In view of the need to withstand the adverse effects of vibration, any securing means employed in the assembly will normally incorporate locking or shape-proof elements or means, but these have not been shown, for the sake of clarity.

Our co-pending United Kingdom Patent Application No.8119221 (V734); No. 8119223 (V725); and No. 8119222 (V750); all of even date, aiso relate to vibration damping handles.

Claims

1. A vibration-damping handle comprising an elongate vibration receiving member for connection at an intermediate point to a device having a body that vibrates, when operating, a pair of first vibration-damping bodies being secured to opposite ends of said vibration receiving member, a pair of second vibration-damping bodies disposed one outside each respective one of said first vibration damping bodies on a common axis and each connected via a respective resilient damper member to the associated first vibrationdamping body, a pair of third vibration-damping bodies disposed on said common axis between said first vibration-damping bodies, a hand-grip member secured to said pair of third vibrationdamping bodies, and tie-rod means linking each said second vibration-damping body to its associated third vibration-damping body through a bore in the associated first vibration-damping body.

2. A handle as claimed in claim 1, in which each said vibration-damping body is concentric with said tie-rod means.

3. A handle as claimed in claim 1 or claim 2, in which all said vibration-damping bodies are symmetrically balanced, and the respective resilient damper members have the same spring constant.

4. A handle as claimed in any preceding claim, in which each said resilient damper member is a spring.

5. A handle as claimed in any one of claims 1 to 3, in which each said resilient damper member is of rubber.

6. A handle as claimed in any preceding claim, in which each of the first vibration-damping bodies is composed of a rigid cup-shaped member having its hollow portion packed with a semi-rigid or elastic material.

7. A handle as claimed in any preceding claim, in which said hand-grip member is tubular, and the third vibration mass bodies are secured to its inner wall.

8. A handle as claimed in any preceding claim, in which said tie-rod means is formed of a metal rod having a diameter of from 5 to 8 mm.

9. A handle as claimed in any preceding claim, in which said tie-rod means extends between said second vibration-damping bodies.

10. A handle as claimed in any one of claims 1 to 8, in which said tie-rod means comprises a separate pair of rods, each extending between a respective second vibration-damping body and its associated third vibration-damping body.

11. A vibration-damping handle substantially as described with reference to Figures 1 and 2.

12. A hand tool having a handle as claimed in any preceding claim.

13. A machine having a handle as claimed in any one of claims 1 to 11.