Gate 3 Group 27 2012 - Revision history

MAE 277 2012 - Group 27: /* Brushless Motor */

2012-12-14T19:26:23Z

Brushless Motor

MAE 277 2012 - Group 27 at 17:42, 14 December 2012

2012-12-14T17:42:32Z

MAE 277 2012 - Group 27: /* Variable gear box */

2012-12-12T22:11:39Z

Variable gear box

MAE 277 2012 - Group 27: /* Engineering Analysis */

2012-12-12T22:08:04Z

Engineering Analysis

MAE 277 2012 - Group 27: /* Engineering Analysis */

2012-12-12T22:07:33Z

Engineering Analysis

MAE 277 2012 - Group 27: /* Engineering Analysis */

2012-12-12T22:05:18Z

Engineering Analysis

MAE 277 2012 - Group 27: /* Product Analysis */

2012-12-12T21:52:22Z

Product Analysis

MAE 277 2012 - Group 27: /* Product Analysis */

2012-12-12T21:49:33Z

Product Analysis

MAE 277 2012 - Group 27: /* Product Analysis */

2012-12-12T21:46:45Z

Product Analysis

MAE 277 2012 - Group 27 at 21:49, 16 November 2012

2012-11-16T21:49:04Z

← Older revision		Revision as of 19:26, 14 December 2012
Line 240:		Line 240:
	===Brushless Motor===		===Brushless Motor===

−	One problem with using a brushed DC motor is that they develop a maximum torque when stationary. The replacement of the existing brushed DC motor with a brushless DC motor offers several advantages that help to curb this problem. For one, brushless motors offer an increased efficiency by providing more torque per watt that a brushed motor. Brushless motors are more efficient at converting electricity into mechanical power than brushed motors. This improvement is largely due to motor's velocity being determined by the frequency at which the electricity is switched, not the voltage. Also, brushless motor is less susceptible wear; with no windings on the rotor, they are not subjected to centrifugal forces, and because the windings are supported by the housing, they can be cooled by conduction, requiring no airflow inside the motor for cooling. This in turn means that the motor's internals can be entirely enclosed and protected from dirt or other foreign matter.	+	One problem with using a brushed DC motor is that they develop a maximum torque when stationary. The replacement of the existing brushed DC motor with a brushless DC motor offers several advantages that help to curb this problem. For one, brushless motors offer an increased efficiency by providing more torque per watt that a brushed motor. Brushless motors are more efficient at converting electricity into mechanical power than brushed motors. This improvement is largely due to motor's velocity being determined by the frequency at which the electricity is switched, not the voltage. Also, brushless motor is less susceptible wear; with no windings on the rotor, they are not subjected to centrifugal forces, and because the windings are supported by the housing, they can be cooled by conduction, requiring no airflow inside the motor for cooling. This in turn means that the motor's internals can be entirely enclosed and protected from dirt or other foreign matter. This reduction in wear represents a design that take societal influence under consideration as the decreased chance of motor failure increases the safety of the user.

@@ Line 173: / Line 173: @@
 There are several factors that influenced the design of the clutch such as global, societal, economic, and environmental considerations.  The majority of the clutch is made out of steel because the clutch needs to be able to withstand high amounts of pressure.  However three of the gears are made out of plastic because they do not need to withstand as much pressure as the other gears.  This decision was made to save the company some money because plastic is cheaper to obtain and work with than steel.  The clutch can be set to different settings by the position collar which allows it to accomplish many tasks in the house hold setting.  The color of the chuck is the same as the steel (silver) because it is an interior component that is not meant to be seen by the user.  The clutch takes environmental factors into consideration because the power of the drill is regulated more efficiently than that of a drill without a clutch.  The interior components of the clutch are greased so friction does not affect the efficiency as much as it would if there was no grease.  The clutch was made using a lathe which is the most cost effective way it could have been made.  The lathe is accurate and does not take away from the strength of the steel.  The plastic gears were made by an injection mold due to the easiness and cheapness of injection molding.
 The clutch is a moderately complex component.  The clutch consists of multiple components and materials which require two to three manufacturing processes.  It does have rotational symmetry but contains more intricate features on the inside.  With all of these factors taken into consideration, it can be safe to say that the overall complexity of the clutch is moderate, having a score of 8.
 ===Solid Model Assembly===

@@ Line 235: / Line 235: @@
 Another revision to our product would be the addition of a pressure sensor that can regulate the speed of the drill. On the economic level since we would like to keep the cost of the drill down.only one pressure sensor would be enough to get the job done. the addition of the pressure sensor would work that way. Located  near the chuck where most of the weight comes down on, the pressure sensor would analyse the force that is put on it to increase or decrease the drill's speed.For example,It is common sense for people to let down on the pressure they put on a drill as their work is being completed, so the drill thanks to its pressure sensor would act accordingly by reducing the speed as well. Nevertheless, that is not to remove and do away with the trigger button but instead it increases the control of the user over the drill and the safety of the drill as well. Therefore, while on the economic level one sensor would keep the drill's cost down, that sensor would also on a societal level increase the safety of the drill and the confidence of its users, by giving them more control over the drill.
-===Variable gear box===
+===Brushless Motor===
-Customers usually prefer products that perform better for the same cost of the product. The third change that can be made is to the planetary gear. Changing the planetary gear box to a variable ratio gearbox would yield the benefit. The cost of changing the gearbox could be substantially more based on the parts, its complexity and its machining. But for the same cost as the planetary gear box the variable gearbox can provide better performance. From an engineering point of view the variable transmission device is preferable to conventional gearbox with fixed gear ratios because variable transmission allows varying combinations of speed and torque to suit the condition and operators preferences. Some of the advantages to mention:
+One problem with using a brushed DC motor is that they develop a maximum torque when stationary. The replacement of the existing brushed DC motor with a brushless DC motor offers several advantages that help to curb this problem. For one, brushless motors offer an increased efficiency by providing more torque per watt that a brushed motor. Brushless motors are more efficient at converting electricity into mechanical power than brushed motors. This improvement is largely due to motor's velocity being determined by the frequency at which the electricity is switched, not the voltage. Also, brushless motor is less susceptible wear;  with no windings on the rotor, they are not subjected to centrifugal forces, and because the windings are supported by the housing, they can be cooled by conduction, requiring no airflow inside the motor for cooling. This in turn means that the motor's internals can be entirely enclosed and protected from dirt or other foreign matter.
-−
-- Improved performance for given energy.
-−
-- Improved torque in the critical low-end revolutions range
-−
-- Reduction in moving mechanical parts
-−
-- Lower wear and maintenance
-−
-But to incorporate this the GSEE factors must be take into account and then make the appropriate changes and enhancements.

@@ Line 222: / Line 222: @@
 <b>Governing Equations</b><br>
-[[File:Equation 272012.png]]
+[[File:Equation 272012.png]] <br>
 n is the number of teeth, and is unitless, and w is the angular velocity, which can be measured in degrees or radians over time, such as radians per second.

@@ Line 223: / Line 223: @@
 <b>Governing Equations</b><br>
 [[File:Equation 272012.png]]
 <b>Discussion</b><br>

@@ Line 212: / Line 212: @@
 <b>Problem Statement</b> <br>
 Determine the optimal planetary gearbox configuration that is designed to input mechanical rotational energy from a motor at a certain speed and torque and output mechanical rotational energy at a predetermined torque and speed that can be adjusted by the drill user.
 <b>Assumptions</b> <br>

@@ Line 154: / Line 154: @@
 The gear has the shape of a flat cylinder, having 18 teeth and axial symmetry, measuring in at 1/4” along its height and ½” along its diameter.  The shape of the teeth is a straight pattern, as opposed to a swirl pattern that one might find in a more complex gear system such as a car transmission.  This straight design was likely chosen because it is simplistic and easy to make.  The gear has slight recessed areas on each surface normal to the axis of rotation.  Because weight is not a significant factor for this part, and plastic has a low density, it can be assumed that the recessed surface is to reduce material cost, and perhaps even help to channel the grease as the gear is moving.  The parts material choice was made based on two factors: the strength it needed to endure and its cost to manufacture.  The plastic gears were chosen to be plastic because they are the first in the series of gear ratio reductions, and thus experience the greatest speed and the lowest stress.  This is where saving weight with plastic helps, but more significantly, it reduces the cost of the product.  These decisions were also subject to the influence of some of the GSEE factors.  Because the part is not seen by the average user, and the user is generally unaware of its existence, it has little influence from global or societal factors.  The plastic material is the cheapest available that is still able to perform the desired function, thus making it a good choice from an economic standpoint.  Being plastic, it has enough durability to have some recessed areas so that it uses less material.  Not only is this economical, but it uses less plastic which is less harmful to the environment.
-The gear is completely enclosed in the drill, thus making aesthetic considerations irrelevant.  As such, the gears are a tan-yellow color, which is likely just the color of the plastic used without any dyes.  The surface finish is smooth but not polished, as this will reduce cost and friction in the product.
+The gear is completely enclosed in the drill, thus making aesthetic considerations irrelevant.  As such, the gears are a tan-yellow color, which is likely just the color of the plastic used without any dyes.  The surface finish is smooth but not polished, as this will reduce cost as well as friction from the surface it rubs against, the surface perpendicular to its axis of rotation.
 The plastic gears were likely to be made via injection molding, as this is the common practice for plastic parts.  The gears are also shaped so that they could easily be separated from a mold.  Injection molding is a common process in modern industry, and as such it has become one of the cheapest options to manufacture parts, making it a good choice from an economic standpoint.

@@ Line 95: / Line 95: @@
 ===Product Analysis===
 <b>Scale for complexity of a component:</b> <br>
-The following chart explains a rating system for judging the complexity of each part.  Under Form, a reverse curve is any curve or recession that would require the part to be rotated or re-positioned to be made.
+The following chart explains a rating system for judging the complexity of each part.  Under Form, the curve is any curve or recession that would require the part to be rotated or re-positioned to be made.
 <u>Table 3.2.1: Complexity Chart</u>
@@ Line 101: / Line 101: @@
 |Function || Add 1 point for each function
 |-
-|Form || Add 1 point for every reverse curve
+|Form || Add 1 point for every curve that requires the part to be rotated
 |-
 | Manufacturing Method || Add 2 points for each manufacturing <br> method required to make the part