GB1591258A

GB1591258A - Alternating current generating set

Info

Publication number: GB1591258A
Application number: GB4279177A
Authority: GB
Original assignee: Nolens Henri C W
Current assignee: Nolens Henri C W
Priority date: 1976-10-25
Filing date: 1977-10-14
Publication date: 1981-06-17
Also published as: IT1087146B; NL159472B; NL159472C; JPS5359819A; BE860061A; SE7711831L; NL7611822A; FR2368816A1; FR2368816B1; DE2746883A1

Description

(54) ALTERNATING CURRENT GENERATING SET (71) I, HENRI CAROLUS WILHELMUS NOLENS, a Subject of the Queen ,of the Netherlands, of Wijkerlaan 8, Voorburg, the Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following state ment:- The invention relates to an alternating current generating set having a prime mover with a variable rate of revolution.

Such generator sets are known. The prime mover therefor is often an internal combustion engine. The generator delivers a current having constant voltage and constant frequency (which are usually 2 to '3% higher at no load than at full load) to an electrical system and therefore has to rotate at a constant rate of revolution. With a bipolar dynamo this rate is 3000 rpm, with a four pole dynamo, 1500 rpm and with a six pole dynamo, 1000 rpm. Any electrical output between no load and full load of the generator may be drawn therefrom. Strongly inductive loads require a much larger input than their nominal maximum input when they are first switched on so that the generator must be able to supply a corresondingly larger output.Moreover, there are often occasions when only a small part of the total load is connected to the electrical system, e.g. only lighting in a domestic installation, larger apparatus, such asian automatic washing machine, 8. dish washer or a heating system, being disconnected. On such occasions the engine rotates in an'underloaded condition.

Furthermore portable'generator sets, which may, during a period of use, supply many different loads may have to operate for long periods under very low load. The engine should, however, always rotåte with' the high' rpm which ' is necessary to generate the'' required voltage and frequency. Such underloading results in disadvantages, such as contamination and wear of the internal combustion engine, the wear being due to the necessarily fixed number of revolutions, unduly high fuel consumption, and more engine noise than is necessary. Also the means for driving the generator often includes a so-called shaft generator, i.e. the engine has a primary function such as supplying the driving power for a ship, vehicle or crane, and powering the generator is a secondary function.Since the shaft velocity for the primary function is not constant, control means between the engine and the generator will be necessary in order to keep the rpm of the generator constant.

The invention aims to provide a generator set whose output shaft has a substantially constant rate of revolution whilst allowing the load to vary or be varied, or the rate of revolution of the engine to vary or to be varied, for example in dependence on the load.

According to the invention, there' is provided a generator set comprising a prime mover, coupled by a vee-groove pulley variator to the shaft of an alternating current generator, said variator comprising' a hydraulic control system arranged to control the transmission ratio of the variator so that the rate of revolution of -the' shaft' of the generator remains substantially constant when the load and/or the rate of revolution of the prime mover change.

The vee-groove pulley variator may be of the type disclosed in Polytechnisch Tijdschrift, Werktuigbouw, 31 No. 9,'September 1976, pages 539-547. This variator,' hereinafter called a Transmátic, has been developed for use both in automobiles andin stationary machines. One version of'the hydraulic control system of the Transmatic is arranged to ensure that the dutput velocíty of the Transmatic remains'corì'stant regardless of variations of load.' This hydraulic control system has a very'fast response.A simple moaification dot'this control system, which modification is known' peP se, enables the output velocity to remain constant even when the rate of revolution of the prime mover changes.

When the invention is to be applied to a shaft generator, the input shaft of the Transmatic is connected to the driving shaft either directly or through a branch shaft or transmission gear connected to the driving shaft.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawing which is a schematic diagram of an alternating current generating set.

The generting set illustrated comprises an internal combustion engine 1, a Transmatic 2 and an electric generator or alternator 3, all mounted on a base member 5. The output shaft of the engine 1 is connected to the input shaft of the Transmatic 2 through an adjustable centrifugal clutch 6 which is so arranged that the internal combustion engine is on load only when its output shaft has reached a predetermined rate of rotation. Means are provided for cooling and lubricating the engine. In the Transmatic 2 itself a multiplate clutch(not shown), controlled by the hydraulic control system thereof, is so arranged that the connection between the engine 1 and the generator 3 is established only after a sufficient oil pressure has built up in the control system. Thereby the internal combustion engine and the generator are safeguarded against overloading during start-up.

The connection between the Transmatic 2 and the generator 3 is provided by a fixed clutch 7, usually, as in the version illustrated, an elastic clutch.

Reference may be had to the abovementioned magazine article for a description of the operation of the Transmatic 2. The Transmatic 2 includes an instrument panel 4 which displays the rates of revolution of the internal combustion engine 1 and the generator 3 as well as the output voltage, current and frequency. This panel also includes a control lever whereby the rate of revolution of the engine 1 may be varied manually dependent on the load of the generator 3.

The power capacity of present commercially available Transmatics varies from about 7-5 to 22 kW with a permitted input shaft rate of revolution of 1000 to 3000 revolutions per minute. The internal combustion engine may then have a maximum power of about 27 HP (= 19 8 kW) at 3000 rpm. The minimum rate of revolution to which the engine is adjustable may be chosen to be e.g. 1500 rpm whereby it remains amply above the minimum rate of revolution of the Transmatic. At 1500 rpm the engine still has a power output of 13 HP. The available electrical power of the generator then varies from about 8 to 20 kW.

The foregoing apparatus operates so that loads, particularly highly inductive loads, are connected when the internal combustion engine is operating at its maximum rate of revolution and therefore producing maximum power, as is the case with known generating sets. Thereafter, however, in contrast to known sets, the rate of revolution of the engine may be decreased in correspondence with the required load, the values being readable from the panel 4. If the required power increases, the frequency of the output current decreases which is an indication that the rate of revolution of the internal combustion engine must be increased. It is possible to carry out said control fully automatically by using the frequency value of the output current for controlling the rate of revolution of the engine.

With all load situations between no load and full load the invention enables the internal combustion engine to operate under optimum conditions.

WHAT I CLAIM IS: 1. A generator set comprising a prime mover coupled by a vee-groove pulley variator to the shaft of an alternating current generator, said variator comprising a hydraulic control system arranged to control the transmission ratio of the variator so that the rate of revolution of the shaft of the generator remains substantially constant when the load and/or the rate of revolution of the prime mover change.

2. A generator set according to claim 1, wherein the prime mover is an internal combustion engine.

3. A generator set substantially as hereinbefore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. either directly or through a branch shaft or transmission gear connected to the driving shaft. An embodiment of the invention will now be described by way of example with reference to the accompanying drawing which is a schematic diagram of an alternating current generating set. The generting set illustrated comprises an internal combustion engine 1, a Transmatic 2 and an electric generator or alternator 3, all mounted on a base member 5. The output shaft of the engine 1 is connected to the input shaft of the Transmatic 2 through an adjustable centrifugal clutch 6 which is so arranged that the internal combustion engine is on load only when its output shaft has reached a predetermined rate of rotation. Means are provided for cooling and lubricating the engine. In the Transmatic 2 itself a multiplate clutch(not shown), controlled by the hydraulic control system thereof, is so arranged that the connection between the engine 1 and the generator 3 is established only after a sufficient oil pressure has built up in the control system. Thereby the internal combustion engine and the generator are safeguarded against overloading during start-up. The connection between the Transmatic 2 and the generator 3 is provided by a fixed clutch 7, usually, as in the version illustrated, an elastic clutch. Reference may be had to the abovementioned magazine article for a description of the operation of the Transmatic 2. The Transmatic 2 includes an instrument panel 4 which displays the rates of revolution of the internal combustion engine 1 and the generator 3 as well as the output voltage, current and frequency. This panel also includes a control lever whereby the rate of revolution of the engine 1 may be varied manually dependent on the load of the generator 3. The power capacity of present commercially available Transmatics varies from about 7-5 to 22 kW with a permitted input shaft rate of revolution of 1000 to 3000 revolutions per minute. The internal combustion engine may then have a maximum power of about 27 HP (= 19 8 kW) at 3000 rpm. The minimum rate of revolution to which the engine is adjustable may be chosen to be e.g. 1500 rpm whereby it remains amply above the minimum rate of revolution of the Transmatic. At 1500 rpm the engine still has a power output of 13 HP. The available electrical power of the generator then varies from about 8 to 20 kW. The foregoing apparatus operates so that loads, particularly highly inductive loads, are connected when the internal combustion engine is operating at its maximum rate of revolution and therefore producing maximum power, as is the case with known generating sets. Thereafter, however, in contrast to known sets, the rate of revolution of the engine may be decreased in correspondence with the required load, the values being readable from the panel 4. If the required power increases, the frequency of the output current decreases which is an indication that the rate of revolution of the internal combustion engine must be increased. It is possible to carry out said control fully automatically by using the frequency value of the output current for controlling the rate of revolution of the engine. With all load situations between no load and full load the invention enables the internal combustion engine to operate under optimum conditions. WHAT I CLAIM IS:

1. A generator set comprising a prime mover coupled by a vee-groove pulley variator to the shaft of an alternating current generator, said variator comprising a hydraulic control system arranged to control the transmission ratio of the variator so that the rate of revolution of the shaft of the generator remains substantially constant when the load and/or the rate of revolution of the prime mover change.