Bike pump

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Figure 1: Competitor product used for dissection study
Figure 1: Competitor product used for dissection study


Contents

Executive Summary

Bicycle pumps come in multiple varieties. This team dissected a floor pump. These are planted on the floor, often secured by the user's feet, attached to the bicycle tube to-be-inflated, and pumped in a vertical axis multiple times until sufficient pressure is reached within the tube. To evaluate the product, we purchased a high-quality Specialized brand floor pump and evaluated the product from manufacture through its consumer life cycle.

Through this analysis, we identified as strengths that the product included many multi-functional parts, had low risks to consumer safety, and had a minimal carbon footprint over its life. Design weaknesses we found include that manufacture involves multiple operations for many components, assembly involves many different interface planes, and much of the diagnostic feedback is inaccessible to the user.

Product Stakeholders

We have identified possible needs and wants for all possible stakeholders. The identified needs are those needs that are essential in order to encourage the stakeholder to use it. The identified wants are additional features that may benefit the stakeholder, however, they are not vital to the use of the product. For the purpose of this study, the consumer is the person pumping up the bike tire, not necessarily the bike owner.


Stakeholder Needs and Wants
Stakeholder Needs Wants
Consumer
  • Product should not require much force or time during pumping process
  • Mechanical advantage and efficiency during the pumping process
  • Intuitive
  • Balances strong performance and minimal cost
  • Lightweight and space efficient
  • Ergonomic
  • Durability
Retailer
  • Cheap & durable materials
  • Efficient storage
  • Aesthetically appealing
  • Standardization
Manufacturer
  • Cheap & easily processed materials
  • Mass production
  • Easy assembly
  • Volume-efficient materials
Shipping & Transportation
  • Lightweight
  • Durability
  • Space-efficient packaging

Product Use Study

The following is a description of how our product is used and key notes and observations from the study.

Step by Step User Study

Requires: Bike tube with standard valve, bike floor pump

First, the user removes the tube valve cap from the bike tire. Second, the user attaches the connection valve to the tube. Third, the user locks the connection valve, creating a seal between the nozzle and the bike tube, which will then allow air to flow into the tire and pump the tire up. Fourth, the uses raises the handle, which raises the piston head inside of the main tube that is connected to the inner rod. As the piston head raises, the o-ring on the piston head is pushes down, opening the seal within the tube and allowing air to enter into the main tube. Fifth, the user depresses the handle. As the handle is depressed, the air within the main tube is pressurized to flow through the pressure-gauge mechanics and readout, through the hose, and into the tire. Sixth, the user monitors the tire pressure gauge by simply looking at the readout. Inside the mechanics of the bike, the airflow presses up on a spring within the pressure-gauge mechanics, moving a coil within the copper pressure-gauge, and in turn, moving the readout needle to accurately display the pressure on the number dial. Finally, the user continues Steps 4-6 until the desired pressure is reached. By continuously lifting and depressing the handle bar, more air is then pumped into the tire and fills the tire to a user-satisfied level of air, creating a more enjoyable bike riding experience.

Removing end cap
Removing end cap
Attaching the connection valve
Attaching the connection valve
Locking the connection valve
Locking the connection valve
Raising the handle
Raising the handle
Depressing the handle
Depressing the handle
Monitoring the gauge while continuing to pump
Monitoring the gauge while continuing to pump

Observation

We noticed that this particular floor bike pump requires that the end handle needs to be flipped up in order to create a connection on the tire. On most floor bike pumps, this handle is first at a 90-degree angle with the entire nozzle head, and is then flipped down to create the seal. This caused a little bit of confusion when users would try to pump up their bike tire, because they were unaccustomed to this style. However, once the connection and seal was created between the entire nozzle head and the tire, the user was able to easily begin pumping up their tire.

It was also observed that, during the tire pumping process, the pressure gauge would read out a higher pressure. After the handle was entire depleted, the readout needle would go down a little bit. This is most likely due to the higher pressure exerted when the tire is being pumped and then the needle adjusts once the pumping process is completed.

Product Mechanical Function

User Input

The user connects the bike pump to the bike tire using the nozzle and locking mechanism. This creates a seal between the pump (from the air flow valve) and the bike tire, allowing for air to be pushed into the tire without losing some to the external environment. Once this seal is created, the pressure gauge shows the current air pressure in the tire and hose (up to the air flow valve). If this pressure is not the desired air pressure, the user lifts up the handle of the pump, filling the chamber with air, and then depresses the handle compressing the air. Once fully depressed, the user will again evaluate the current tire pressure and determine if it is still undesirable. Once the air pressure in the tire is sufficient, the user unlocks the nozzle and removes it from the tire, which contains its own sealing mechanism as to not lose air.

Airflow

When the user connects the bike pump to the bike tire, air flows through the hose to the pressure gauge and stops at the air flow valve at the base of the main chamber (which works using a compression spring). When the user pulls up the handle, air is drawn in from the top of the chamber where there is no sealing device and flows past the piston head, which has a rubber o-ring that acts somewhat like a valve due to part geometry allowing air to flow past it on an upstroke but creating a seal on the downstroke, and stops at the air flow valve. Once the chamber is filled with air, the user depresses the handle, compressing the air in the chamber. Once the air pressure in the chamber is greater than the force from the spring holding the air flow valve in place the spring depresses, allowing air to flow from the chamber into the bike tire. When the handle is fully depressed and there is no more air in the chamber, the spring re-extends, sealing the air in the tire and hose allowing the user to draw more air into the chamber by pulling up the handle again and repeating the process. When the user unlocks the nozzle and removes it from the tire, the air left in the hose is lost to the environment and the tire creates it's own seal to keep air in.

Assembly

This is a blow-up view of our assembly, with parts labeled.

Assembly


Sub-Assembly

The following are close-ups and exploded views of various subassembly photos .

Pressure-gauge readout sub-assembly
Pressure-gauge readout sub-assembly
Piston chamber sub-assembly
Piston chamber sub-assembly
Nozzle sub-assembly
Nozzle sub-assembly
Hose sub-assembly
Hose sub-assembly

Bill of Materials

The following is a bill of materials from the bike pump dissection. The parts can be sorted based on part number, quantity, weight or material by clicking on the appropriate tab at the top of the table.


Part Number Name QTY Weight (g) Function Material Manufacturing Process Image
1 Screw54Holds base support (#8) in place to metal base (#31)SteelThread rolling
Screw
Screw
2 Nut51Attaches screws (#1) to metal base (#31)SteelInjection molding
Nut
Nut
3 Rubber readout cover130Holds plastic readout cover (#4) in place above pressure gauge mechanics (#23)RubberInjection Molding
Rubber readout cover
Rubber readout cover
4 Plastic readout cover112Provides clear screen and protection to number dial readout (#10)PlasticInjection Molding
Plastic readout cover
Plastic readout cover
5 Metal connection valve tip15Holds rubber connection valve tip (#6) in place AluminumPress Molding + Threading
Metal connection valve tip
Metal connection valve tip
6 Rubber connection valve tip12Creates seal onto bike tube valveRubberInjection Molding
Rubber connection valve tip
Rubber connection valve tip
7 Air hose holder (double)112Holds air hose (#32) to main tube (#30) during storagePlasticInjection Molding
Air hose holder (double)
Air hose holder (double)
8 Plastic base support110Reduces cantilever stresses on outer arm tubePlasticInjection Molding
Plastic base support
Plastic base support
9 #7 O-Ring2< 1Provides necessary friction to hold the double air hose holder (#7) onto outer arm tube (#30) and allow for vertical movement along axis of tubeRubberInjection Molding
#7 O-Ring
#7 O-Ring
10 Readout number dial13Provides a quantified tire pressure readoutAluminumSheet Stamped
Readout number dial
Readout number dial
11 Readout needle1< 1Displays the quantified tire pressure on (#10 AluminumPress Stamped
Readout needle
Readout needle
12 #13 O-Ring2< 1Provides seal on bike tube inside the pump stabalizer (#13)RubberInjection Molding
#13 Rubber seal
#13 Rubber seal
13 Pump stabalizer113Allows metal rod (#19) to move within the main tube (#30)PlasticInjection Molding
Pump stabalizer
Pump stabalizer
14 Piston head18Acts as a pump to draw in air within the main tube (#30) and then compress the airPlasticInjection Molding
Piston head
Piston head
15 Tube connector24Connects hose (#32) to nozzle (#39) and to the metal base (#31)PlasticInjection Molding
Tube connector
Tube connector
16 Air hose holder (single)12Holds air hose (#32) to main tube (#30) during storagePlasticInjection Molding
Air hose holder (single)
Air hose holder (single)
17 Handle bar1127Allows user to apply downward force to draw and compress air in the main tube (#30)PlasticInjection Molding
Handle bar
Handle bar
18 End cap26Provides a covering to the ends of the handle barPlasticInjection Molding
End cap
End cap
19 Metal rod1174Connects piston head (#14) to the handle bar (#17)SteelExtrusion + Crimp
Metal rod
Metal rod
20 Stopper1< 1Blocks airflow during upstrokeRubberInjection Molding
Stopper
Stopper
21 Spring1< 1Pushes up stopperSteelCoiled Wire
Spring
Spring
22 O-Ring1< 1Creates sealRubberInjection Molding
O-Ring
O-Ring
23 Pressure gauge mechanics150Converts air pressure to angular displacementCopper Purchased
Pressure gauge mechanics
Pressure gauge mechanics
24 Small screw2< 1Fixes pressure gauge housingSteel Thread Rolling
Small screw
Small screw
25 Air flow director149Guides air flow from piston to hosePlasticInjection Molding + Threading
Air flow director
Air flow director
26 #27 O-Ring1< 1Provides a seal to the hose-to-nozzle connector (#27)RubberInjection Molding
#27 O-Ring
#27 O-Ring
27 Hose-to-nozzle connector1< 1Allows air to flow from hose to nozzlePlasticInjection molding
Hose-to-nozzle connector
Hose-to-nozzle connector
28 Seal between #25 & #291< 1Provides a seal between the air flow director (#25) and the base-to-hose (#29)RubberInjection Molding
Seal between #25 & #29
Seal between #25 & #29
29 Base-to-hose connector17Provides a connection between hose (#32) and air flow director (#25)PlasticInjection Molding
Base-to-hose connector
Base-to-hose connector
30 Main tube1238House pistonSteelInjection Molding + Threading
Main tube
Main tube
31 Metal base1540Provides counter force from upstrokeSteelMolded + Drill Pressed
Metal base
Metal base
32 Hose183Encloses from base to nozzleRubberExtrusion
Hose
Hose
33 Weighted handle insert1~200Pulls metal rod (#19) down to starting position by gravity Aluminum Lathed
Weighted handle insert
Weighted handle insert
34 Valve connection housing1~30Gripping surfacePlasticInjection Molding
Valve connection housing
Valve connection housing
35 Valve channel1~20Channels air through handlePlasticInjection Molding
Valve channel
Valve channel
36 Tire interface valve1~20Puts air in tireSteel Molded
Tire interface valve
Tire interface valve
37 Readout housing1~50Protection of pressure gaugeSteelPress Molded
Readout housing
Readout housing
38 Piston chamber end cap1~10Fixes main tube to baseSteel Molded
Piston chamber end cap
Piston chamber end cap
39 Nozzle1~300Assembles all components of nozzle (#34-#38) togetherPlasticMolded
Nozzle
Nozzle

Design for Manufacture and Assembly (DFMA)

DFMA is a combination of two practices, Design for Manufacture (DFM) and Design for Assembly (DFA). DFM is the method of designing part so that they're manufacturing processes are simplest, and DFA is the method of designing parts that will lead to a simple assembly process at the plant or by the user.

Manufacturing

The competitor product we analyzed displayed numerous positive manufacturing features that would minimize cost and complexity. The overall design is surprisingly simple, a result of combining features into single parts where possible, using only a few different materials, and minimizing the overall part count. From a manufacturing standpoint, all components are very successfully produced, but the part that could use the most improvement is the piston chamber end cap (#38) for it involved several manufacturing processes and an additional painting process not seen on any other parts.

Below are some of the DFM Guidelines and the observations we made of how our competitor designed their product with those guidelines in mind and some areas we believe they could improve.

Design for Manufacturing Features and Improvements
Design Objective Strengths Areas of Improvement
Minimize Part Count
  • Few fasteners, mostly everything screws and locks together
  • Many multifunctional components leading to less parts overall
Standardize Design Features
  • All screws in the system are identical
  • Since there are few fasteners, most parts are custom-made for this product
Keep Designs Simple
  • Piston shows a clever design to allow air into the pump on upstroke while eliminating lost air on downstroke, while still remaining very simple
  • Pressure gauge is very complex, needs fine adjustment and much protection
Multifunctional Parts
  • Many parts serve a specific purpose while also screwing into the next assembling acting as both a functional piece and connector
Ease of fabrication
  • Mostly composed of some type of plastic and steel
  • The plastic parts are for the most part unique and would each need their own mold
Avoid Tight Tolerances
  • Uses flexible rubber o-rings to allow for larger tolerances while remaining airtight
Minimize Secondary & Finishing Operations
  • Since parts are multifunctional, most would require at least would need a secondary threading operation

Assembly

Assembly of the competitor's product is not the consumer's responsibility and occurs prior to the retail stages in the supply chain. The product requires tools and fasteners only where the piston chamber attaches to the base, and nearly all of the remaining interfaces are threaded. While minimizing toolage, this raises many challenges with orientation and radial symmetry where the assembly process could be made clearer. The variety of O-rings, springs, and cylinder diameters is another weakness that has room for improvement.

Due to the assembly process being deliberately separated from the consumer, ease of assembly is not a high priority and leaves room for redesign towards simplicity.


Design for Assembly Features and Improvements
Design Objective Strengths Areas of Improvement
Minimize Part Count
  • There’s the metal piece in the handle we can’t account for
  • Air flow pathway has several components
Minimize Assembly Surfaces
  • Baseplate has multiple interfaces, axes
  • Piston has multiple planes and axes
Use Sub-assemblies
  • Pressure Gauge is a discrete system
  • Air compression mechanics are limited to main tube
  • Nozzle is a discrete system
  • Functional testing requires end-to-end assembly
Mistake-Proof
  • Asymmetric Handlebar
  • Many radially symmetric parts
Minimize Fasteners
  • Most of the assembly is screwed together
  • Tools and fasteners required for fixing main tube to base
Minimize Handling
  • Hose attachments have conical guides
  • Interfaces have many different axes and planes
Minimize Assembly Direction
  • Two distinct possible assembly directions (Nozzle or Handle)
Provide Unobstructed Access
  • Base plate obscures airflow components
  • Nozzle has multiple hidden components
  • Pressure gauge mechanics are hard to access
Maximize Assembly Compliance

Failure Modes & Effects Analysis (FMEA)

Failure Modes and Effects Analysis (FMEA) is a failure analysis system often utilized to examine possible failure modes within a system for classification by failure mode, severity, likelihood and detection of the modes of failure.

After analyzing the different failure modes, we have concluded that this product has a very low failure risks and therefore low risk of harm to the user. This is due to the simplicity of the design and that our product is strictly mechanical; electrical connections would most likely add more failure modes to the product. On the other hand, this product deals with high air pressure situations so it is also a delicate instrument which comes with delicate parts. The connection valve has the most parts and therefore the most chances of failing when being used. At the same time, a lot of failures may occur due to the high air pressure which is invisible to the user.

The following is the scale that we have utilized to study the possible effects and failure modes of our product.

Scale used for determining numerical values for failure severity, likelihood and detectability
Scale used for determining numerical values for failure severity, likelihood and detectability


Failure Modes and Effects Analysis - Floor Bike Pump
Item & Function Failure Mode Effects of Failure S Causes of Failure O Design Controls D RPN Recommended Actions
Valve Nozzle ConnectorAir leaking out of wheelBike tube loses air3Misalignment to valve2Check if it locks212Something to help user better secure nozzle properly
Does not lockNo air transfer into wheel3User not using it correctly2Check if it locks318Something that does not use a lock, Make it easier to lock
Valve may not fitNo air transfer into wheel1Wrong valve type4Check if it locks416Make a universal valve, Provide adapters
Pressure GaugeAir leaking out of wheelWon't display pressure2Broken gauge1Test in manufacturing plant24Better pressure gauge tube seal, Different pressure reading technique
Incorrectly calibratedDisplays incorrect pressure reading2Dropping gauge, Manufacturing error 1Test in manufacturing plant714--
Handle rodBendsCan not apply downward force, Breaks rod5Bars are physically bent forward and not down, Damaged, Improper use2--770Stronger rod
TubeAir leaking out of wheelLoss of air from tire3Misuse, Damage3--436Tube wrapped in durable material


User description:

Able bodied people will most likely be using this product because it involves pumping a tire of a bicycle which is something only able bodied people can use. Children might possibly attempt using these products.


Situational usage:

Product will only be used to pump tires, basketballs, and other inflated objects.

Design for Environment (DFE)

Design for Environment (DFE) can help bring focus to specific areas when improving a design. By analyzing the entire life cycle, the areas of the largest impact can be determined and minimized.


Design for Environment
-- Production Use
Item Consumed Bike Pump Bike
Sector # and Name #339920: Sporting and athletic goods manufacturing #336991: Motorcycle, bicycle, and parts manufacturing
Reference Unit 1 Bike Pump 1 Bike
Units consumed per product life 1 1
Cost Per Unit* $39.04 $234.27
Lifetime Cost* $39.04 $234.27
Sector mtCO2e per $1M 613 543
Implied mtCO2e per product life 0.0239 0.1272
CO2e Tax @ $30/mtCO2e $0.72 $3.82

*2002 USD

Production

Using the sporting and athletic goods manufacturing sector of EIO-LCA, we were able to estimate the environmental impact of producing the bike pump. The bike pump costs $50 today, which is about $39.04 in 2002. Power generation and supply has the largest contribution to the 613 mtCO2e per 1 million dollars spent in the sporting and athletic goods manufacturing category. Therefore we can estimate that for every bike pump produced 0.0239 mtCO2e is released into the environment, resulting in a minor $0.72 tax per pump. However, we believe this is an overestimation because the bike pump is a small portion of the Other sporting and athletic equipment sector which is only 7.6% of the Sporting and athletic goods manufacturing sector we used in the calculations.

Sector #339920: Sporting and athletic goods manufacturing

Economic Activity: $1 Million Dollars

Displaying: Greenhouse Gases

Number of Sectors: Top 10



Use

If the consumer purchases a bike pump, we can assume that they own at least one bike. Therefore we used the EIO-LCA Motorcycle, bicycle, and parts manufacturing sector to study the environmental impact of use of the pump. We estimated that today the average bike costs $300 which equates to about $234.27 in 2002. Our analysis approximated a small $3.82 tax per bike.

Sector #336991: Motorcycle, bicycle, and parts manufacturing

Economic Activity: $1 Million Dollars

Displaying: Greenhouse Gases

Number of Sectors: Top 10




Group Dynamic

Group 2: JR, Patrick, Dinesh, Lauren, Amber
Group 2: JR, Patrick, Dinesh, Lauren, Amber

Team Leader: Dinesh Ayyappan

DFMA Lead: Patrick Hogan

FMEA Lead: Jonathan Wong

DFE Lead: Amber Ohiokpehai

Wiki Lead/Report Compilation: Lauren Milisits

References

Michalek, Lectures 1-4, Pittsburgh, 9/3/2012-9/14/2012

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