Patent Application
20110005024
The subject matter disclosed herein relates generally to speed regulating systems for small engines. More particularly, the subject matter disclosed herein relates to arrangements and uses for engine speed governors.
Small combustion engines can be used in a wide variety of power equipment. For instance, a pressure washer, log splitter, lawnmower, air compressor, generator or the like can use an internal combustion engine to power a working component (e.g., a high pressure water pump, hydraulic pump, cutting blade). In typical pressure washers, a speed regulation system can be provided for maintaining the engine speed within a governed speed range. Referring to
In this common configuration, as the speed of the engine increases, a moment is generated on the rotatable shaft of the centrifugal device, which in turn causes the rotation of governor arm 110. This rotation moves governor rod 112 to move throttle control TC toward a closed position. In this way, the speed regulation system maintains the engine speed within a predefined governed speed range.
The particular governed speed range can be set by adjusting the tension on governor spring 116. For instance, this adjustment can typically involve bending the portion of governor arm 110 that is connected to governor spring 116 or changing the spring mount on frame element 120. This adjustment is usually only made at the time of manufacture or while the engine is being serviced. As a result, in order to achieve the best possible performance, equipment manufacturers tend to set the governed speed range to a relatively high engine speed to maximize the pump flow, pressure, cutting performance, or other performance characteristic. Because the governor speed range is not easily adjustable, the engine runs in this high speed range regardless of whether or not the pump or blade is doing work.
With regard to pumps in particular, this single governed speed range can be problematic due to the fact that pumps generally exhibit two basic engine load scenarios. In a first mode, a valve is actuated to allow the pump to pressurize and flow fluid and do work. In this condition, the pump is applying a very high load to the engine. In a second mode, the valve is not actuated, which does not allow the pump to flow water or do any net work. In this condition, the pump is applying a very light load to the engine. As a result, typical use involves a significant amount of time where the valve is not being actuated and the pump is not doing work. Accordingly, there are several problems that exist because the engine runs at a high speed even in its unloaded state (i.e., when the valve is not being actuated), including high levels of noise emitted from the engine, reductions in pump life and engine life by running at a high speed, and higher fuel consumption than it would be at a lower speed.
Accordingly, it would be advantageous for a small power machine such as a pressure washer, log splitter, lawnmower, air compressor, generator or the like to include a control system that can achieve a large automatic reduction in engine idling speed without requiring any additional system integration, such as a water pressure control line tied into the pressure washer pump. At the same time, it is further advantageous that the engine still responds quickly (i.e., resumes high speed operation) when a load is applied.
In accordance with this disclosure, arrangements and uses for engine speed governors are provided. In one aspect, an automatic idle system for a small engine is provided. The automatic idle system can include an engine speed governor for connection to a small engine. The governor can include a governor shaft rotatable in response to a speed of the engine. A governor linkage or fixed governor arm can include a first portion for connection to the governor shaft and a second portion for connection to a throttle control of the engine, and the first portion can be movably connected with the second portion, such as by the first portion being pivotably coupled to the second portion. An actuator can be connected to the second portion of the governor linkage, the actuator being movable in response to a load on the engine to move the second portion relative to the first portion from a base position to an adjusted position. In this configuration, when the engine is in a low-load state, the second portion can be moved such as by pivoting relative to the first portion toward a throttle-closed position.
In another aspect, a pressure washer is provided. The pressure washer can include an engine drivingly engaged to a pump, an engine speed governor coupled to the engine, a governor linkage connecting the engine speed governor to a throttle control of the engine, and an actuator. The engine can include an adjustable throttle and a switch or valve movable between an ON position in which water is allowed to flow from the pump and an OFF position in which water is prevented from flowing from the pump. The governor can include a governor shaft rotatable in response to a speed of the engine, and the governor linkage can include a first portion connected to the governor shaft and a second portion connected to a throttle control of the engine. The first portion can be movably connected with, such as by a pivotably coupled connection, the second portion, and the actuator can be connected to the second portion of the governor linkage, the actuator being movable in response to a load on the engine to move, such as pivoting, the second portion relative to the first portion from a base position to an adjusted position. As a result, when the switch is in the off position, the second portion can be moved, such as by pivoting, relative to the first portion toward a throttle-closed position.
In yet another aspect, a method for automatically adjusting the speed of an engine is provided. The method can include coupling an engine speed governor to a small engine, the governor comprising a governor shaft rotatable in response to a speed of the engine. The method can further include connecting a governor linkage between the governor shaft and a throttle control of the engine, with the governor linkage comprising a first portion connected to the governor shaft and a second portion connected to the throttle control, and the first portion being movably connected with, such as by being pivotably coupled with or to the second portion. The method can also include moving an actuator in response to a load on the engine to move the second portion relative to the first portion from a base position to an adjusted position. In this way, when the engine is in a low-load state, the second portion is moved relative to the first portion toward a throttle-closed position.
Some of the objects of the subject matter disclosed herein having been stated hereinabove, and which are achieved in whole or in part by the presently disclosed subject matter, other objects will become evident as the description proceeds when taken in connection with the accompanying drawings as best described hereinbelow.
The features and advantages of the present subject matter will be more readily understood from the following detailed description which should be read in conjunction with the accompanying drawings that are given merely byway of explanatory and non-limiting example, and in which:
The present subject matter provides automatic low speed idle systems and methods for small engines. In one aspect, the present subject matter provides a system that is designed to automatically lower the engine speed below the governed speed range when the engine is in a low-load state (i.e., when a pressure washer trigger is not pulled). In particular, referring to
Regardless of the specific use of small engine E, an automatic idle system, generally designated 200, can include an engine speed governor G coupled to engine E. Referring to the particular configuration illustrated in
Where governor linkage 210 can differ from conventional governor arm 110 is that governor linkage 210 can be a multi-piece component. In particular, governor linkage 210 can include a first portion 212 connected to governor shaft GS and a second portion 214 connected to a throttle control TC of engine E. First portion 212 can be movably connected with, such as by being pivotably coupled to, second portion 214 at a pivot point P.
Despite governor linkage 210 comprising multiple pieces rather than a single governor arm, governor linkage 210 can function in a substantially similar manner to the conventional governor arm under loaded conditions. Specifically, when the speed of engine E is relatively low, governor linkage 210 can be in a base position (e.g., “straight” position) shown in
The multi-piece configuration of governor linkage 210 provides additional functionality, however, by adjusting the position of throttle control TC depending on the load on the engine as well as on the speed of the engine. To accomplish this load-based adjustment, an actuator 220 can be connected to second portion 214 of governor linkage 210. Actuator 220 can be movable in response to a load on engine E to move, such as by pivoting, second portion 214 relative to first portion 212 from the base position to an adjusted position. Specifically, when the engine is in a low-load state, actuator 220 can move second portion 214 to the adjusted position in which second portion 214 is moved or pivoted relative to first portion 212 to move throttle control TC toward a throttle-closed position.
Once a load is placed on the engine, actuator 220 can allow second portion 214 to move back so that governor linkage 210 is again in the base position. In addition, governor linkage 210 can further include a rigid stop 216 to prevent second portion 214 from moving further than a maximum desired rotation to limit the amount that the operation of actuator 220 can affect the adjustment of throttle control TC. Governor linkage can also include a biasing mechanism, such as a spring, which can bias second portion 214 toward the base position. In addition, actuator 220 can be designed so that the operation of engine governor G and the vacuum characteristics of engine E are able to overcome the force applied by actuator 220 without a substantial decrease in the engine speed after the engine encounters a load. In this way, automatic idle system 200 allows engine E to respond quickly to the load condition.
In one particular embodiment, actuator 220 can be a vacuum actuator in communication with carburetor C of engine E. Specifically, referring to
For instance, second portion 214 can have a raised feature 218 (shown in
Regardless of the specific configuration, actuator 220 can be thus be connected between carburetor C and governor linkage 210. Referring to the system shown in
In this arrangement, the engine's natural vacuum characteristics can move actuator 220 to the appropriate position depending on whether engine E should run in the high governed speed range or in the low speed idle state. For instance,
Therefore, as discussed above, actuator 220 can be designed such that at high loads, when the intake tract pressure can be relatively close to atmospheric pressure, actuator 220 can move actuation rod 226 to be in an extended position. Further, actuator 220 can have an internal spring, generally designated 228, that applies a force on diaphragm 224 to return actuation rod 226 to its extended position when the internal pressure is above a certain level. Conversely, at low loads, the relatively low intake tract pressure causes actuator 220 to move actuation rod 226 to a retracted position.
With a configuration such as described above, the system can operate as follows. When engine E is running at a high load, the intake tract pressure can be high enough that actuation rod 226 of actuator 220 can be in its extended position, allowing the governor system to move freely without any effects. Therefore in a high load condition, governor linkage 210 can be both geometrically and functionally the same as it would be on an engine equipped with a conventional governor arm arrangement. This configuration thus causes engine E to run in its typical, relatively high speed range when the engine is loaded (e.g., when the pressure washer trigger is pulled).
When engine E is running at a light load, the intake tract pressure can be low enough that actuation rod 226 of actuator 220 can be in its retracted position. This position causes second portion 214 of governor linkage 210 to move, such as by pivoting, thereby moving throttle control TC to close the carburetor throttle and thereby reduce the engine speed. Additionally, there can be a stop 216 at or near pivot point P so that second portion 214 can only travel a predetermined amount or distance relative to first portion 212. Because of this limitation on the rotation of second portion 214, actuator 220 also applies some tension to governor spring 116 when it is retracted. The net result of these actions can be a relatively low idle speed when the load on engine E is low.
For example, if automatic idle system 200 is incorporated into a pressure washer system, a user actuating a switch S, such as a trigger on a nozzle-containing wand W, can be moved between an ON position in which water is allowed to flow from pump P and an OFF position in which water is prevented from flowing from pump P. In the ON position, the operation of pump P exerts a load on engine E. While this load is applied, automatic idle system 200 can operate in a manner substantially similar to a traditional governor arm. When switch S is released to stop the flow of water, however, the reduction of load on engine E can cause actuator 220 to move second portion 214 of governor linkage 210 so that throttle control TC is moved toward a throttle-closed position. As a result, engine E can automatically idle at a much lower speed when little or no load is applied to the engine. This automatic idle can help to reduce the level of noise emitted from the engine, increase the life of the engine and driven components (e.g., water pump) by reducing the number of revolutions of the engine (per unit time) when little or no load is applied, and decrease the overall fuel consumption of the engine because the engine consumes less fuel when it is idling at lower speeds.
In addition, it is to be understood that the present subject matter is not limited solely to applications to engine-driven pressure washer systems. It is believed that the presently disclosed automatic low-speed idle systems and methods can be used in applications where the engine has two distinct loading scenarios: a high load when the machine is doing work and a very low load when it is not doing work. Some examples include but are not limited to log splitters, lawnmowers with a blade clutch, garden tillers, and portable hydraulic power units.
The present subject matter can be embodied in other forms without departure from the spirit and essential characteristics thereof. The embodiments described therefore are to be considered in all respects as illustrative and not restrictive. Although the present subject matter has been described in terms of certain preferred embodiments, other embodiments that are apparent to those of ordinary skill in the art are also within the scope of the present subject matter.
