GB2124916A - Exercise apparatus - Google Patents

Abstract

A pivotally mounted beam, arranged to be lifted by a user, is connected to an hydraulic piston and cylinder device 10, the pressure of the hydraulic fluid supplied thereto being controlled by an electric circuit and an electro-magnetic valve 16 to resist movement of the beam by the user in accordance with one of three characteristics, ie constant resistance, variable resistance and isokinetic operation. The position of the beam is sensed by a measuring device 18 and the starting position of the beam may be varied hydraulically against a pneumatic pressure bias provided by an air reservoir 17. <IMAGE>

Description

SPECIFICATION Exercise apparatus The present invention relates to exercise apparatus.

The lifting of weights by athletes and others is in general use for the improvement of strength, fitness and physique. This form of exercise conventionally employs detachable weights mounted on bars or weight stacks on sliding rods which may be lifted by systems of levers or pulleys.

It has been found that strength and muscle bulk will be increased more rapidly if either the resistance the user experiences to his movement changes over the range of the movement or if the movement is isokinetic; that is performed at constant speed, any tendency by the user to increase the speed of movement being counteracted by an increase of the resistance against which he is working. Although the effects described above may be achieved on mechanical exercise machines by a combination of sliding weights, friction devices and hydraulic dampers, the effects are not easily controlled or adjusted and it is very difficult to construct a single machine which will produce all the characteristics described above or will enable a large range of exercises to be undertaken.

The present inventon provides an exercise apparatus comprising a member movable by a user, a piston and a cylinder device connected to the member for applying a force to the member to resist movement by the user, monitoring means for monitoring the piston of the member and for outputting a signal indicative of the position of the member, a source of fluid for supply to the piston and cylinder device, and a control unit operable in response to said signal for controlling the pressure of fluid supplied to the piston and cylinder device whereby to control the force which the user must exert in order to move the member.

The invention enables up to three characteristics, constant resistance, variable resistance or isokinetic operation to be easily selected, adjusted and controlled and a wide range of exercise to be performed.

Other advantages over conventional mechanical machines include low weigh and safety in use and accrue due to the use of fluid pressure rather than gravity to provide the resistance against which the user works.

In order that the present invention be more readily understood, an embodiment thereof will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows an embodiment of the present invention; and Figure 2 shows a circuit diagram of control apparatus for use with the embodiment shown in Figure 1.

As shown in Figure 1 a rectangular steel frame '1' has at one end a platform '2' upon which the user stands or lies on a bench (not shown in Figure 1). A beam '3' is attached by means of a pivot '4' to an upright '5' which is fixed to the opposite end of the frame from the platform. Fixed to the opposite end of the beam from the pivot '4' is a sleeve '6' and turnbuckle '7', into which various operating handles (one example of which is shown '8') may be rapidly and firmly attached. A double-acting hydraulic cylinder '10' has the end of its piston rod attached to pivot '11', which is in turn attached to beam '3'. The other end of the hydraulic cylinder '10' is attached to a pivot '12' which is in its turn attached to the framework '1'. An electric motor '13' drives an hydraulic pump '14' which is fed with hydraulic fluid contained in a tank '15'.A proportional electromagnetic valve '16' controls the output pressure delivered by the pump '14', the hydraulic fluid being returned to the tank '1 5'. Avalve '16' delivers hydraulic fluid at a pressure which is a function of the current delivered by the electronic control unit (not shown in Figure 1) to the top of the cylinder '10'.

A pipe connects the bottom of cylinder '10' to a sealed pressure vessel '17'. The vessel which is large in volume compared with the swept volume of the cylinder '10', contains air in sufficient pressure to force the piston in cylinder '10' to the top of its stroke and hence the beam '3' to its highest position when no hydraulic pressure is applied to the top of the cylinder.

Monitoring means in the form of a position measuring device '18' which may conveniently be a potentiometer is attached via the pivot '4' to the beam '3' in such a manner that an electrical signal is derived that is porportional to the position of beam '3'. The cylinder '10' has a stroke and an attachment point to the beam '3' such that the operating handle '8' may describe an arc which at one end allows the handle '8' to touch the platform '2' and, at the other end of the arc, to rise to a height approximately 7 ft.

above the platform '2'.

The method of operation of the invention will now be described by reference to both sketch Figure 1 and the block diagram of the electronic control unit shown within the dotted rectangle in Figure 2.

The signal from the position measuring device '18'. which may for the purpose of this description be assumed to increase in magnitude as the height of the handle '8' above the platform '2' increases, is connected to comparitor '19', the other input of which is connected to a control '25' which provides a manually variable voltage. The output from the position measuring device '18' is also connected to a differentiator '20'. The output from the comparitor '19' is connected to an adder '21' via a gain control '22'. The output from the differentiator '20' is supplied to a comparitor '26' which in turn provides an output to the adder '21' only when the output from the differentiator '20' exceeds the voltage provided by a manually variable voltage source '27'.

Additionally, the comparitor '19' is also supplied to the gating unit '24', the other input of which is fed from the output of the adder '21'. The output of the gating unit is fed to the proportional electromagnetic control valve '16'.

The method of operation of the invention may be most readily understood if it is assumed initially that the variable gain control '22' is set to the zero gain position and that the setting of the control '27' is such that no signal from the differentiator 20 can be fed to the adder '21'. When no power is supplied to the system, for reasons previously explained the beam '3' will be at its highest position. When power is supplied to the system, a signal fed from the variable voltage control '23' via adder '21' and gating unit '24' will cause the control valve '16' to deliver hydraulic fluid at a pressure determined by the setting of the variable control '23' to the top of the hydraulic cylinder '10', causing the beam '3' to fall.

As the beam falls the voltage from the position measuring device '18' falls until it approaches the value of the voltage provided from the control '25'.

At this point, the output from the comparitor '19' starts to fall sharply but progressively and reduces the signal fed from the gating unit '24' to the electromagnetic control valve '16', which in its turn reduces the hydraulic pressure in the cylinder '10' until the pressure provided by the hydraulic fluid on the piston in cylinder'10' balances the pneumatic pressure provided by the reservoir '17'. The beam is, therefore, arrested at a position determined by the control '25'. It will be apparent to those skilled in the art that the position servo just described enables the beam to be adjusted to any desired position.

If the user, by use of the control '25', sets the handles '8', e.g. to shoulder level, and pushes upwards in the exercise known as a shoulder press and the force is sufficient the beam will move upwards causing the output from position measuring device '18' to exceed the voltage provided by the control '25', which in its turn causes comparitor '19' to cause the gating unit '24' to permit the voltage from the control '23' to be fed via the adder '21' to the electromagnetic control valve '16'. Hence, the force at which the user must exert is determined by the setting of the control '23'.

To summarise the foregoing - control '25' controls the position of the beam and control '23' controls the force which the user will have to exert in an upward direction on the handles in order to displace the beam upwards.

There will now be described the method by which the variable resistance characteristic is achieved.

If the gain control '22' is adjusted in such a direction so as to increase the proportion of the output from comparitor '19' that is fed to the adder '21' then as the beam is raised the signal fed to the control valve '16' consists of the sum of the output of the variable voltage source '23' and a voltage proportional to the distance by which the beam '3' is raised above its equilibrium position. Hence, hydraulic pressure applied to the top of cylinder '10' rises as the beam is raised and the user experiences a rising resistance as he raises the beam.

There will now be described the method by which the isokinetic characteristic is achieved.

Let it be assumed that the gain control '22' is set at the zero gain position. As the velocity with which the user raises the beam is increased, the output from differentiator '20' rises until it reaches the magnitude of the voltage provided by the manually adjustable voltage source '27', at which point the comparitor '26' provides an output to adder '21' in such a direction that the hydraulic pressure controlled by the electromagnetic valve '16' rises and the velocity of the beam is thereby reduced. It will be readily apparent to those skilled in the art that the mechanism just described constitutes a velocity servo, the maximum velocity of the beam '3' being determined by the setting of the variable voltage source '27'.

The invention, therefore, provides an exercise machine the rest position of the operating beam of which may be varied over a wide range by means of the control '25'; the initial force of which may be varied by the control '23', the variable resistance characteristice of which may be varied by the control '22' and the isokinetic characteristic of which may be varied by the control '27'.

It will be readily appreciated by those familiar with weight training programmes that many different exercises can be performed on the invention. An example of exercises that can be performed when the machine is fitted with the handles '8' shown in Figure 1 include: Dead Lift Front Shoulder Press Back Shoulder Press Bench Press Shoulder Shrug By loosening turnbuckle '7', handle '8' may be slid out of sleeve '6' and replaced by other operating devices to enable parts of the body other than the hands to be used to move the beams. Among the exercises for which the other operating devices may be used are Upright Rowing Bent Over Rowing Straight Arm Pull Over Bent Arm Pull Over Tricep Press Also, the working fluid could be pneumatic rather than hydraulic.

Claims (8)

1. An exercise apparatus comprising a member movable by a user, a piston and cylinder device connected to the member for applying a force to the member to resist movement by the user, monitoring means for monitoring the piston of the member and for outputting a signal indicative of the position of the member, a source of fluid for supply to the piston and cylinder device, and a control unit operable in response to said signal for controlling the pressure of fluid supplied to the piston and cylinder device whereby to control the force which the user must exert in order to move the member.

2. An exercise apparatus as claimed in claim 1 wherein the control unit comprises means for determining the rest position of the beam.

3. An exercise apparatus as claimed in claims 1 or 2, wherein the control unit comprises means for determining the force a user will have to exert to displace the beam.

4. An exercise apparatus as claimed in claims 1, 2 or 3 wherein the control unit comprises means for controlling the resistance of movement of the beam.

5. An exercise apparatus as claimed in any preceding claim wherein the control unit comprises means for controlline the velocity of the beam.

6. An exercise apparatus as claimed in any preceding claim wherein the source of fluid comprises a motor for driving a pump, which pump is fed with hydraulic fluid, a valve for controlling the output pressure delivered by the pump, and a pressure vessel for containing air to force the piston to the top of its stroke.

7. An exercise apparatus as claimed in any preceding claim, wherein the member is pivotally mounted for movement in the vertical plane.

8. An exercise apparatus as hereinbefore described with reference to the accompanying drawings.