如何使线条更长并成为$I_M$线条？

Question

这是我的代码。

\documentclass[12pt,letterpaper]{article}    
\usepackage[left=20mm,top=30mm,bottom=30mm,right=20mm]{geometry}
\usepackage{tikz}  % for drawing pictures
\usetikzlibrary{arrows.meta,
                chains,
                positioning,
                quotes,
                shapes.geometric, arrows}

\begin{tikzpicture}[auto, 
                node distance = 15mm and 10mm,
                start chain = going right,
                arr/.style = {->},>=Latex,
                block/.style = {draw, minimum height=3em, minimum
                width=4em,align=center,fill=blue!20},
                sum/.style = {circle, draw, node contents={}},    
                        ]
                \begin{scope}[nodes={on chain, join=by arr}]        
                \coordinate (in);
                
                \node (n2) [block] {$n_2$};                      
                \node (n4) [block] {$K$};

            \node (n1) [sum];
                \coordinate (out);
                \end{scope}
                
                 \node (n5) [block, above=of n4] {$\mbox{\huge$\times$}$};
                \node (n11) [block, above=of n5] {$K_M$};
            \node (n12)  [block, below=of n4] {$N()$};

                \path   (n4) to [pos=0.8,"$r~~~+$"] (n1)

                          to ["$y_f$"{name=y}]        (out);         



            
                \draw [->] (n11) -- (n5);
                \draw[-]  (n12.west) -- ++ (-6mm, 0) |- (n5.west) node[above left] {$+$};
                \draw[-]  (n12.east) -- ++ (20mm, 0) |- (n5.east) node[above right] {$+$};
                    
\end{tikzpicture}

\end{document}

这是我得到的。我不知道如何让这条线更长。

这就是我想要实现的目标。

我是说这条线，已经用红笔标记了。见下图。

Answer 1

\documentclass[tikz, border=1cm]{standalone}
\usetikzlibrary{arrows.meta, chains, quotes}
\begin{document}
\begin{tikzpicture}[
node distance=15mm and 10mm,
start chain=going right,
arr/.style={->}, >=Latex,
block/.style={draw, minimum height=3em, minimum
width=4em, align=center, fill=blue!20},
sum/.style={circle, draw, node contents={}},    
]
\begin{scope}[nodes={on chain, join=by arr}]        
\coordinate (in);
\node[block] (n2) {$n_2$};                      
\node[block] (n4) {$K$};
\node[xshift=3cm] (n1) [sum];
\coordinate (out);
\end{scope}
\node[block, above=of n4] (n5) {$\mbox{\huge$\times$}$};
\node[block, above=of n5] (n11) {$K_M$};
\node[block, below=of n4] (n12) {$N()$};
\path (n4) to[pos=0.8,"$r~~~+$"] (n1) to["$y_f$"{name=y}] (out);         
\draw[->] (n11) -- (n5);
\draw  (n12.west) -- ++ (-6mm, 0) |- (n5.west) node[above left] {$+$};
\draw  (n12.east) -- ++ (20mm, 0) |- (n5.east) node[above right] {$+$};
\end{tikzpicture}
\end{document}