油門踏板的 A 與 B 靠在一起了,你即使鬆開油門踏板,踏板也回不來了,因為 A 與 B 之間太緊密了,摩擦力太大了,超過了彈簧的張力。
那為何豐田車子會突然加速呢?按照物理學常識,油門踏板由於 A 與 B 過緊而不能彈回來,那油門也不會加大,雖然不會減小。其實,對這個問題我沒看到解釋。以潤濤閻的猜測,也就是理論和邏輯推理,是因為開車的人發現油門沒回來,卡住了,就想去踩一下,讓它彈回來。可這一踩不要緊,油門踏板的 A 與 B 的接觸麵更大了,摩擦力也更大了,它就無法彈回來了不算,油門也加大了。這就是那位警察開Lexus 車子跑到120 邁的速度才撞毀的緣故。
您如果仔仔細細讀完了上麵潤濤閻的解釋,您就應該知道了:加上一塊鐵片,油門踏板的 A 與 B 就無法讓油門開到最大了。因為油門開不到最大,真空管裏的真空就能夠讓刹車不失靈。也就是說,豐田的這個補救辦法不是說車子以後不會卡住油門了,而是卡住後,也不會刹不住車。即使駕駛員反複放開刹車,因為真空沒問題,車子還會刹住的。
當然,豐田說以後不會卡住了。其實,道理在於:由於 A 與 B 的接觸麵積不能達到原來那麽大了,摩擦力也就不會那麽大了。但潤濤閻以為:那塊鐵片不能太厚,因為太厚就無法加速了。也就是說,卡住的事還會發生的,隻是即使發生,刹車係統不失靈,導致送命的情況就少了。車子能刹住,發動機發瘋,那就讓它瘋一會好了。等你停下來,把發動機關掉,車子冷下來後,油門踏板一冷縮, A 與 B 之間就不那麽緊了,彈簧就把它彈回來了。你再上路,繼續享受開車的刺激。隻要沒有生命危險,有點刺激是人生的一種額外享受,要不怎麽那麽多人花錢去轉那個6 flag 、迪尼斯之類的呢?
在所有的日本車中,隻有Subaru 出的所有車種都是達標的G (好),其它的日本車有一個是本田的 Honda Element 達標外,全部不達標。隻是因為美國高速公路管理局還沒有把翻車能活下來作為指標,日本人就鑽這個空子。尤其是豐田,連一輛達標的車都沒有,豐田出了那麽多種車,沒有一種車是 G 。假如你開的不是Subaru ,而是其它日本車,那你就要小心了,千萬別翻車,一旦翻車,你和乘客性命難保。
The CTS pedal has a friction arm that is designed to generate a certain degree of friction necessary for the proper functioning of the electronic gas pedal. In our earlier tear down and analysis, we pointed out that the CTS design is inferior to others, such as the Denso unit also used in Toyotas. The friction arm is subject to wear and contamination that increases friction to the point of creating a sticky gas pedal.
The friction arm is a pivoted fulcrum; the end with the “friction teeth” rides in two grooved channels in the pedal assembly. Both these parts are made from plastic. The other end of the friction arm is held in place by the return spring, which exerts the pressure necessary to generate the friction. As the friction teeth wear, the gap on the other end increases in relation to the housing. Toyota’s shim is inserted in this gap in order to reduce/limit the amount of friction, and to compensate for wear.
The gap is to be measured by a feeler gauge (photo above), which determines the thickness of shim that is then inserted in the gap. The shim then limits the travel of the fulctum on the spring end, thereby reducing the amount of friction on the teeth as they ride in the grooves.
The next step is to open the gap by inserting a narrow-shank screwdriver, so that the correctly-sized shim can be installed. The unit has been turned upside down to facilitate that.
The shim (gray steel) is now slid in, and positioned behind a lip that serves to retain it. The shim is kept in place by the pressure of the return spring on the fulcrum, but we wonder whether a strong jolt might not be able to dislodge it. If it did become dislodged, it could potentially cause serious problems. No one would ever design a unit like this with a loose metal shim that was held in place by spring pressure only.
The next picture shows the shim all the way in place behind the lip. It’s a good thing that lip exists, otherwise this fix would not be possible.
The photo above shows the inside of the unit, with the friction arm extending forward. The shim is clearly visible as the shiny gray rectangle. The pivot axles extending out on both sides of the fulcrum/friction arm are visible as two small white/gray pieces, just below and to both sides of the shim. The friction teeth are visible towards the front of the unit, riding (now higher) in their grooves.
This photo above was taken previously of the same pedal. It’s difficult to tell exactly from the slightly different angles whether the teeth are riding higher with the shim, but it does appear so. And a subjective impression was that the pedal had somewhat less friction. So the fix may well reduce the friction below a dangerous level, but for how long?
The only way we interpret the necessity of measuring the friction arm gap and choosing an appropriately sized shim is that the older units with more wear will have a smaller gap than the new(er) ones. The shim will compensate for that wear, but in a static, not dynamic way. As soon as the continued wear on the friction arm changes its size or other friction characteristics, the pedal is potentially back to the same sticky situation as before.
The shim’s effect on reducing the amount of friction will presumably slow down the wear process, but intrinsically, this is not a permanent fix to a very critical part, from a safety point of view. This is why the CTS-type pedal design is flawed, because it is subject to changes in the amount of friction it generates due to wear and other factors.
The only other explanation for the varying gap size and different shims is that the manufacturing tolerances are so great, that this is necessary to compensate for them. That’s that hard to imagine, for such a critical part. But if so, it raises other serious questions about this unit. Either way, it reinforces our position that Toyota needs to replace all the CTS pedals with Denso pedals or another proven pedal design, as soon as they are available. The shim fix is a Band Aid, and does not inspire the confidence that Toyota urgently needs to instill in its customers and the market place at this critical time.
Update: Given that Toyota has acknowledged that these pedal assemblies cost them $15, it would obviously be cheaper (and more reliable) to swap out the CTS units with the Denso unit rather than this fussier and riskier fix. The problem is time; it could take many months if not a year or more to change tooling and produce 2.3 million units. Meanwhile, making these shims was obviously something that a stamping manufacturer could do in days.
閻兄, 我剛買個二手的Chrysler Town&Country van. 開了幾次,總共不到50邁就不走了. AUTO SHOP 說我被SCAMMED了,TRANSMISSION IS GONE. 有可能那DEALER在裏邊加了點東西, 讓TRANSMISSION可以多活幾天.
想問問你的看法, 咱對車是外行.
謝了.
Toyota Motor Corp.’s China car sales beat General Motors Corp.’s in the first nine months of the year, as the Japanese company threatens to end GM’s 77-year reign as the world’s largest automaker.
Toyota’s two Chinese ventures boosted nine-month sales 30 percent to 407,427 cars and sport-utility vehicles. GM’s car sales were little changed at 373,945, according to Bloomberg calculations based on data issued by the China Association of Automobile Manufacturers.
回複cecil的評論:
Cecil,我相信您很專業,不過太過於全盤否定了,樓主本來就不在這裏發表學術論文,細節錯誤是很可能的,文章並不是以技術語言寫成的,技術細節不可能精確。至於"日本車的零件是兩層皮的", it is just a figure of speech. I don't take it literally. 我喜歡這篇文章的要點,樓主的風格就是誇張個人觀點!This is a place for expressing yourself. One's writing style may be exaggerated but entertaining, as long as the main ideas are based on facts. It does not have to be politically correct, or academically measured?
ee1994 發表評論於
我有個問題請教樓主:how to find out whether a toyota car has CTS gas padel or Denso gas padel? We have a 2001 toyota camry and a 2006 toyota prius. They are not currently in recall list. But I want to find out more about our fmaily cars. 謝謝
我都不想在這裏重新貼回樓主指 "豐田回收修車後會令極速減低,而普通車主不覺",這種不負責任和誹謗的言論。記錄我是有的,樓主你更改就得嗎?文章可以更改,但無知是改不了,這些全無技術的批評簡直是小孩都不如,何況是出自個博士的文章???
本人就不是博士,不是 a range of car 的車主,不是經常發表 Blog, 這裏出文都是因為樓主而注冊。
An article with detailed information, analysis, and data based not on hearsays or isolated examples, but on rich personal experience over a long period and covers a range of cars.
Those who have owned less than a handful of cars but are willing to comment have a good will, too, to prove from the other sides.
But they need to widen the perspective and learn how to debate, rather than merely drop a line or two saying it is not valid.
“So the fix may well reduce the friction below a dangerous level, but for how long?
The only way we interpret the necessity of measuring the friction arm gap and choosing an appropriately sized shim is that the older units with more wear will have a smaller gap than the new(er) ones. The shim will compensate for that wear, but in a static, not dynamic way. As soon as the continued wear on the friction arm changes its size or other friction characteristics, the pedal is potentially back to the same sticky situation as before.”
Why does Toyota need outside help? Insiders are often helpless with those events of very low probability.
A certain drug was suspected of suddenly causing deaths to patients in China. The top authority set a deadline to experts to solve the problem. All the tests showed the product was OK. Meanwhile, the police opened a separate criminal investigation, and detectives interviewed all the production staff. The police knew nothing about technology, but they did find out the only change was an insignificant procedure in another product.This clue from police helped the experts to identify the tiny amount of impurity.
By the way, Black Swan is a good book about the improbable.
solo1 發表評論於
I never have had a car from Toyota, but a friend found out the unintended acceleration of Toyota Camry about two years ago during the first test drive at the dealer. He thought it was a system design problem and not a big deal, so he bought the car. His advice: Just do not press the gas pedal too harsh. He is quite experienced, from the days of repairing tractors and combines at Beidafan.
thanks for your comments. however,"the explanation with different thermal expansion for brake failure" is not what i thought. i said that "the explanation with different thermal expansion ... for gas pedal...".
i believe that the vaccum is the cause for the brake failure.
Best regards!
solo1 發表評論於
The author certainly has real knowledge and hands-on experience with cars. But the explanation with different thermal expansion for brake failure seems not valid. Toyota does not give a convincing explanation either.
The rare and non-reproducible problem is very difficult for inside experts. The president of Toyota admitted this and asked for outside help. Unfortunately he turned to the wrong people, or quality control people, for help. Quality control is the strength of Japanese cars. Mr. Toyoda should ask someone like the author for help.
I have a question about Toyota cars.
I bought a 2009 Toyota Corolla LE. Since the VIN of this car starts with "J", I did not receive any letter for recall.
Can you tell me the difference of car manufactured in Japan and in other country?
I have driven this car for 10 months. It is still pretty good and smooth. Do you suggest I should sell this car?
Thanks a lot
Power steering使用液壓也同時需要真空?給個鏈接看看?俺在汽車行業也呆了不少年了,倒是第一次聽說。你所說的corolla的例子不成立,俺恰巧知道corolla的power steering是不用真空做動力的。但當操作轉向時power steering確實會通過一個真空開關提高發動機轉速(車速很低時)以增加轉向助力。
閻先生 is misleading the readers: Shifting to 1st or 2nd gear while the engine is running at high RPM is not going to slow down the car. First, with automatic transmission, shifting to 1st or 2nd gear doesn't mean you will get 1st or 2nd gear immediately. The onboard computer will look at the car speed and shift from 5th to 4th, 3rd and 2nd and 1st gear depending on the car speed. This is to prevent damage to the transmission. Second, when engine speed can be as high as 6K to 7K RPM when gas padel is stuck, you car can still be accelerating (If you drove a manual shift before, you know this).
Follow NHTSA's recommendation and shift to "Neutral" when the gas pade is stuck!
I have a 206 Camry. I have the same problem. The brake is very weak. Honda and Nissan have much better brakes. Also
changing to softer brake pads helps. The 350Z's brake is very very good although the pads don't last long.
回複潤濤閻的評論:
1) is incorrect. If brake parts (rotors and pads) become too hot, brake will not function normally and that's called "Fade". That's why you should not put your foot on brake when going down hill for a long time. I personally experienced brake "fake" with Nissan 350Z for several times. Read "Car and Driver" and you will find that this is a common issue with sports cars.
估計豐田有人看了樓主的文章,終於考慮安裝‘刹車是爺係統’了。
Japanese carmaker Toyota will add a brake-override system to all new vehicles as it seeks to recover from a global car recall.
About roof strength: I just checked IIHS test results, and Japanese cars are some of the best. For example, in Midsize moderately priced cars catogery, Toyota Camry is rated good, having the BEST strength-to-weight ratio of 5.31. Compared to Ford Fusion's 3.33, and even the Volvo S40 has only 3.92 (both rated acceptable). See http://www.iihs.org/ratings/roof/detailsbyclass.aspx?30
Conclusion: either the author purposefully misleads readers, or he does not know what he is talking about.
Maybe the driver accidentally dropped a piece of magnetic stone or something, that caused a a confusion.
Boy, taking a closer look at this pedal, i am so scared, it "IS CONNECTED TO THIN ELECTRONIC WIRES!!!!!", I always imagined there is a metal lever connect to the throttle! Does anyone know if a BMW X5 (2006 model) is also connected through a wire?
有道理。Several comments:
1。日本車做工精細但不經撞,美國車經撞但做工粗糙,這個 開車的人都知道。之
所以人們多買日本車,恐怕更多的還是出於耐用性的考慮。買車也是權衡各種利弊
的一個過程。今後人們在選車時可能會把安全性的權重加高而選擇歐美車,畢竟生
命的意義遠高於其他一切。日本車肯定會失去一部分market share, American car
may get some。但恐怕歐洲車會 gain the most if think about the quality and
reliability。
2。沒看懂為什麽油門全打開後刹車的真空會lost。感覺給油和刹車是兩個不同的係
統。難道它們是coupled的嗎?如果是coupled的,那很可能電控和軟件may play bigger
roles in the failure。懂行的給解釋一下?
3。跟換檔一樣,switch off "Over drive" 也可以改變齒輪的傳速比達到減速的目
的。
Some of the author's opinions make sense. Other's not:
1) Camry has weak brakes. This is true. But Honda and Nissan have good brakes. I own a Camry, a Odessey and a Nissan 350Z. The camry brake is really really weak and my wife almost tailgated the car in front the first time she drove it. Toyota really did a poor job on the brake.
2) Poor American drives Japanese cars. This is not true. A lot of my co-workers, some of them are rich and none of them are poor, drive Japanese cars. They buy Japanese cars because American cars have developed very poor reputation in the last 20 years.
3) Used Toyotas are priced cheap. This is no longer true in last 10 years. Toyotas resale value is much higher than American cars now (before the recalls).
If I found the car stops reacting I will try putting it to N (neutral) first, if that fails I will turn off the engine. And I will step on the brake with all forces, and perhaps apply the handbrake as well. It will take the Lexus 30 seconds to go to 120 mph. Obviously the police guy is not thinking - he had time to talk to 911 but his should focus on thinking...
The thermal expansion coefficients of carbon steel with different strength would be roughly the same. But there may be considerable differences if special alloys are used.
Could you please explain more indetail on your statement: "而刹車用的 power brake (動力刹車係統),需要真空"? I though the "power break" machnism was "pressure" from an oil-cylinder, instead of "vacuum". Thanks!
我的地址: zheng88usa@yahoo.com.
Thanks for your attention.
felicia_f 發表評論於
好文章謝謝啦
starwars 發表評論於
牛人.閻大哥在那裏修車?
東方邪 發表評論於
閻大俠全才啊,長見識了。
marxu 發表評論於
高!實在是高!
留意 發表評論於
尼桑是不是更差勁啊?我家有一輛VAN,不知道刹車是不是也有問題。
yyang3 發表評論於
回複planojw的評論:
1. Is 日本車 the only one that has recall?
others recall voluntarily, toyota is the only one not so voluntarily.
2. Is this the first recall ever happen to 日本車?
same as 1.
3. Why this recall has such high publicity?
think it this way, if you hold all the recalls from past 10 years into one day, did you think it will get high publicity? I would say it not high enough yet.
4. There are 19 death caused by car issue. What's the default % from all the people who owns 日本車?
are you saying when SUA happens, only certain % of your body will die?
5. How many people had accident due to reasons are not car defacts?
what's the difference? the accident caused by car defect are not accident?
6. Does every part necessary to be built by steel? If so, you probably need to drive a tank rather than car.
so you are driving a car made of plastic, uh, in another word, a toy car?
7. Some non-Jap car makers products will require frequent visit to dealership, even the warranty is free. Is that high quality?
jap quality is not high quality, when I was in china, I did repair a lot electronics, and I learned what beauty on surface means by open those jap electronics. after came here I start repair cars, and I learned it again by open those jap cars.
I personally think this recall hype is 08's way of promoting US cars.
obviously you came here not long. if u know that happened to Audi during 80s and Mitsubishi during 90s, you will understand what happened now.
Before we conclude that 日本車 are all poorly built, let's ask ourselves following questions:
1. Is 日本車 the only one that has recall?
2. Is this the first recall ever happen to 日本車?
3. Why this recall has such high publicity?
4. There are 19 death caused by car issue. What's the default % from all the people who owns 日本車?
5. How many people had accident due to reasons are not car defacts?
6. Does every part necessary to be built by steel? If so, you probably need to drive a tank rather than car.
7. Some non-Jap car makers products will require frequent visit to dealership, even the warranty is free. Is that high quality?
I personally think this recall hype is 08's way of promoting US cars.
jewishgirl 發表評論於
How about 99VW passat?
Does it have brake assitant? Is that good?
We are lucky. We just sold our Camry last summer and we have two VW now.
purenaturalhoney 發表評論於
大長了學問,謝謝。不過我開的是2008年的Prius, 隻有R,N, D, B 這幾襠,假如油門失靈的話,我應該放到哪一檔上呢?
不勝感激。
totally agree, especially the 兩層皮, another example, the nuts and bolts used on jap car are soooooooooo soft, it is impossible to not break a bolt when working on a old jap car.
油門踏板的 A 與 B 靠在一起了,你即使鬆開油門踏板,踏板也回不來了,因為 A 與 B 之間太緊密了,摩擦力太大了,超過了彈簧的張力。
那為何豐田車子會突然加速呢?按照物理學常識,油門踏板由於 A 與 B 過緊而不能彈回來,那油門也不會加大,雖然不會減小。其實,對這個問題我沒看到解釋。以潤濤閻的猜測,也就是理論和邏輯推理,是因為開車的人發現油門沒回來,卡住了,就想去踩一下,讓它彈回來。可這一踩不要緊,油門踏板的 A 與 B 的接觸麵更大了,摩擦力也更大了,它就無法彈回來了不算,油門也加大了。這就是那位警察開Lexus 車子跑到120 邁的速度才撞毀的緣故。
您如果仔仔細細讀完了上麵潤濤閻的解釋,您就應該知道了:加上一塊鐵片,油門踏板的 A 與 B 就無法讓油門開到最大了。因為油門開不到最大,真空管裏的真空就能夠讓刹車不失靈。也就是說,豐田的這個補救辦法不是說車子以後不會卡住油門了,而是卡住後,也不會刹不住車。即使駕駛員反複放開刹車,因為真空沒問題,車子還會刹住的。
當然,豐田說以後不會卡住了。其實,道理在於:由於 A 與 B 的接觸麵積不能達到原來那麽大了,摩擦力也就不會那麽大了。但潤濤閻以為:那塊鐵片不能太厚,因為太厚就無法加速了。也就是說,卡住的事還會發生的,隻是即使發生,刹車係統不失靈,導致送命的情況就少了。車子能刹住,發動機發瘋,那就讓它瘋一會好了。等你停下來,把發動機關掉,車子冷下來後,油門踏板一冷縮, A 與 B 之間就不那麽緊了,彈簧就把它彈回來了。你再上路,繼續享受開車的刺激。隻要沒有生命危險,有點刺激是人生的一種額外享受,要不怎麽那麽多人花錢去轉那個6 flag 、迪尼斯之類的呢?
在所有的日本車中,隻有Subaru 出的所有車種都是達標的G (好),其它的日本車有一個是本田的 Honda Element 達標外,全部不達標。隻是因為美國高速公路管理局還沒有把翻車能活下來作為指標,日本人就鑽這個空子。尤其是豐田,連一輛達標的車都沒有,豐田出了那麽多種車,沒有一種車是 G 。假如你開的不是Subaru ,而是其它日本車,那你就要小心了,千萬別翻車,一旦翻車,你和乘客性命難保。
The CTS pedal has a friction arm that is designed to generate a certain degree of friction necessary for the proper functioning of the electronic gas pedal. In our earlier tear down and analysis, we pointed out that the CTS design is inferior to others, such as the Denso unit also used in Toyotas. The friction arm is subject to wear and contamination that increases friction to the point of creating a sticky gas pedal.
The friction arm is a pivoted fulcrum; the end with the “friction teeth” rides in two grooved channels in the pedal assembly. Both these parts are made from plastic. The other end of the friction arm is held in place by the return spring, which exerts the pressure necessary to generate the friction. As the friction teeth wear, the gap on the other end increases in relation to the housing. Toyota’s shim is inserted in this gap in order to reduce/limit the amount of friction, and to compensate for wear.
The gap is to be measured by a feeler gauge (photo above), which determines the thickness of shim that is then inserted in the gap. The shim then limits the travel of the fulctum on the spring end, thereby reducing the amount of friction on the teeth as they ride in the grooves.
The next step is to open the gap by inserting a narrow-shank screwdriver, so that the correctly-sized shim can be installed. The unit has been turned upside down to facilitate that.
The shim (gray steel) is now slid in, and positioned behind a lip that serves to retain it. The shim is kept in place by the pressure of the return spring on the fulcrum, but we wonder whether a strong jolt might not be able to dislodge it. If it did become dislodged, it could potentially cause serious problems. No one would ever design a unit like this with a loose metal shim that was held in place by spring pressure only.
The next picture shows the shim all the way in place behind the lip. It’s a good thing that lip exists, otherwise this fix would not be possible.
The photo above shows the inside of the unit, with the friction arm extending forward. The shim is clearly visible as the shiny gray rectangle. The pivot axles extending out on both sides of the fulcrum/friction arm are visible as two small white/gray pieces, just below and to both sides of the shim. The friction teeth are visible towards the front of the unit, riding (now higher) in their grooves.
This photo above was taken previously of the same pedal. It’s difficult to tell exactly from the slightly different angles whether the teeth are riding higher with the shim, but it does appear so. And a subjective impression was that the pedal had somewhat less friction. So the fix may well reduce the friction below a dangerous level, but for how long?
The only way we interpret the necessity of measuring the friction arm gap and choosing an appropriately sized shim is that the older units with more wear will have a smaller gap than the new(er) ones. The shim will compensate for that wear, but in a static, not dynamic way. As soon as the continued wear on the friction arm changes its size or other friction characteristics, the pedal is potentially back to the same sticky situation as before.
The shim’s effect on reducing the amount of friction will presumably slow down the wear process, but intrinsically, this is not a permanent fix to a very critical part, from a safety point of view. This is why the CTS-type pedal design is flawed, because it is subject to changes in the amount of friction it generates due to wear and other factors.
The only other explanation for the varying gap size and different shims is that the manufacturing tolerances are so great, that this is necessary to compensate for them. That’s that hard to imagine, for such a critical part. But if so, it raises other serious questions about this unit. Either way, it reinforces our position that Toyota needs to replace all the CTS pedals with Denso pedals or another proven pedal design, as soon as they are available. The shim fix is a Band Aid, and does not inspire the confidence that Toyota urgently needs to instill in its customers and the market place at this critical time.
Update: Given that Toyota has acknowledged that these pedal assemblies cost them $15, it would obviously be cheaper (and more reliable) to swap out the CTS units with the Denso unit rather than this fussier and riskier fix. The problem is time; it could take many months if not a year or more to change tooling and produce 2.3 million units. Meanwhile, making these shims was obviously something that a stamping manufacturer could do in days.